back to indexNutrients For Brain Health & Performance | Huberman Lab Podcast #42
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Welcome to the Huberman Lab Podcast,
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where we discuss science and science-based tools
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for everyday life.
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I'm Andrew Huberman, and I'm a professor of neurobiology
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and ophthalmology at Stanford School of Medicine.
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Today, we are talking all about food and the brain.
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We are going to talk about foods that are good
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for your brain in terms of focus,
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in terms of brain health generally,
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and the longevity of your brain,
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your ability to maintain cognition
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and clear thinking over time.
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We are also going to talk about why
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and how you prefer certain foods to others.
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And I'm going to talk about the three major signals
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that combine to drive your food choices.
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I'll give you a little hint of what those are.
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One of those signals comes from your gut
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and is completely subconscious.
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This is not the gut microbiome per se.
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These are neurons in your gut that are sending signals
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to your brain that you are unaware of
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about the nutrient contents of the foods
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that you're eating.
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The second signal is how metabolically accessible
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a given food is, meaning how readily that food
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can be converted into energy that your brain,
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not your body, but that your brain can use.
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And the third signal is perhaps the most interesting one.
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It's the signal of belief.
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It's the signal of what you perceive and believe,
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the food that you're eating to contain,
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and what you think it can do for you health-wise
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And that might sound a little wishy-washy or vague,
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but we're going to provide mechanistic data
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to support the fact that you can change what you eat,
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so much so that you can drive your brain and your body
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to crave foods that are good for you,
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or at least better for you than the foods
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you might currently be eating.
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This is an incredibly powerful mechanism that we all have.
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It's one that I think is very underappreciated.
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And today I'm going to review the data
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from both animal models and fortunately more recently,
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human studies that really do underscore the fact
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that you can control your desire for particular foods.
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Before we dive into today's topic,
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I just want to briefly touch on some key takeaways
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from a previous episode,
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which is the episode on time-restricted feeding,
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also called intermittent fasting.
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The key elements of time-restricted feeding
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that will benefit your health the most
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in terms of weight loss or maintenance, fat loss,
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organ health, quality sleep, and cognition
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are that the feeding window begin
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at least one hour after waking.
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You could push that feeding window out to begin later,
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but at least one hour after waking,
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and that it end at least two and ideally three hours
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before going to sleep.
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Some people can end that feeding window
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much further away from the beginning of sleep,
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meaning they're finishing their last bite of food,
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for instance, at 6 p.m.
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and they're not going to sleep until midnight.
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But many people struggle to get quality sleep
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if that feeding window is set too early
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relative to when they go to sleep.
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So begin the feeding window at least one hour after waking,
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end the feeding window at least two hours
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before going to sleep.
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And a key feature based on the scientific research
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is that the feeding window itself fall more or less
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at the same period of each 24-hour day from day to day,
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meaning if you are going to eat over an eight-hour period,
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that's your feeding window,
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you wouldn't want to start that feeding window
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at 10 a.m. one day and end it at 6 p.m.,
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and then the next day start at noon and end it at 8 p.m.,
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and the next day start it at 2 p.m.
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and end it at 10 p.m. and so forth.
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As much as is reasonably possible,
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if you want to extract the maximum benefit
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from time-restricted feeding,
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the idea is to keep that feeding window
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at more or less the same phase, as it's called,
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of each 24-hour day.
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If it slides around a little bit for social reasons
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or whatever reasons, it doesn't seem to be a big deal,
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but you don't want it sliding around
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by many hours from day to day
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because of the way that that feeding window
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impacts other genes called clock genes
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that regulate a bunch of other processes in the body.
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Before we begin, I'd like to emphasize
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that this podcast is separate
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from my teaching and research roles at Stanford.
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It is, however, part of my desire and effort
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to bring zero-cost-to-consumer information
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about science and science-related tools
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to the general public.
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In keeping with that theme,
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I'd like to thank the sponsors of today's podcast.
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Our first sponsor is Roca.
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Roca makes eyeglasses and sunglasses
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that are of the absolute highest quality.
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I've spent a career working on the visual system,
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and one of the key problems that Roca sunglasses has solved
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is if you've ever worn sunglasses
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and you've gone from a very bright region
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to, say, a region with shadows,
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oftentimes you have to take the sunglasses off.
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They've designed their sunglasses in a way
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that no matter whether you're standing in the shade
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or in bright sunlight, you will always see things
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with absolute crystal clarity, which is wonderful.
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Their eyeglasses as well are designed
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so that you can move from one region of brightness
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to another without noticing it at all.
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The other thing that's really terrific
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about Roca eyeglasses and sunglasses
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is that they are very lightweight.
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Most of the time, you don't even remember
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and you can wear them whether or not
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you're exercising or working
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because they won't slip off even if you get sweaty.
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The other thing that's really wonderful
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is that the aesthetic is terrific.
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Unlike a lot of so-called performance glasses out there
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that make people look like cyborgs,
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or frankly, just look rather strange,
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Roca eyeglasses and sunglasses have a terrific aesthetic.
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You can wear them to dinner, to work, running, exercising,
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and they'll work for all those situations.
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If you'd like to try Roca, you can go to roca.com,
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that's R-O-K-A.com, and enter the code Huberman
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to save 20% on your first order.
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Today's episode is also brought to us by Athletic Greens.
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Athletic Greens is a vitamin mineral probiotic drink
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that's designed to cover your foundational supplementation
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I've been using Athletic Greens since 2012,
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so I'm delighted that they're sponsoring the podcast.
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The reason I started using Athletic Greens
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and the reason I still drink Athletic Greens
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once or twice per day
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is because it covers all of my vitamin mineral basic needs
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and because of the probiotics.
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There's now ample data supporting the fact
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that probiotics support a healthy gut microbiome
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and that the gut microbiome is important
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for keeping inflammation low, which is good,
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as well as for supporting the immune system
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and for supporting brain health
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through the so-called gut-brain axis.
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If you'd like to try Athletic Greens,
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you can go to athleticgreens.com slash Huberman,
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and if you do that, you can claim a special offer.
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They'll give you five free travel packs,
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so these packs make it really easy to mix up Athletic Greens
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and they'll give you a year's supply of vitamin D3K2.
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There's now a lot of data pointing to the fact
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that vitamin D3 and K2 are important for hormonal health,
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and so if you go to athleticgreens.com slash Huberman,
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you'll get the Athletic Greens,
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and a year's supply of vitamin D3K2.
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Today's episode is also brought to us by Headspace.
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Headspace is a meditation app
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backed by 25 peer-reviewed published studies.
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I think by now, most people have heard
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of the benefits of meditation,
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reduce stress, improve sleep, better cognition, et cetera.
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I've been meditating for a long time,
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but I have to admit it's been sort of an on and off thing.
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There are periods of time over the last 10
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or gosh, even 20 or 30 years
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that I've meditated consistently,
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and then I'll stop meditating.
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One of the terrific things about Headspace
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is that it has meditations
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of different duration and different type,
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so I found that as soon as I started using Headspace,
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that I was meditating far more consistently.
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One of the great things about meditation
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is that it works the first time and it works every time,
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and the more consistently I do it,
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the more positive benefits I seem to derive.
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go to headspace.com slash special offer.
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I'd like to point you toward what I think
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is a very valuable zero-cost resource online.
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Recently, I took part in an event called
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Rethink Education that was put on by Logitech,
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and there I gave a 20-minute lecture
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where I describe the classic
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and modern neuroplasticity literature
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in both animal models and humans.
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The neuroplasticity literature is, of course,
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the literature that describes how to rewire the brain
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in order to learn.
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During that 20-minute talk, I described that literature,
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but I also spell out what I call
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the neuroplasticity super protocol,
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which is nine plus steps of things
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that teachers can apply in the classroom
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to teach any sort of information,
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music, math, sports, anything,
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and that students of any kind in any age
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can use to enhance the speed and depth of learning.
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You can find that talk on YouTube
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by following the link in the caption to this episode,
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or by simply going to YouTube
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and entering the search terms Logitech Huberman.
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Some of the most frequent questions I get
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are about food and the brain.
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Everybody seems to want to know what they should eat
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and what they shouldn't eat
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in order to have peak brain function,
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to be able to focus and memorize things and so forth,
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and in order to maintain brain health over time,
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because nobody wants to lose their memory
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or have troubles with cognition.
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Fortunately, there are a lot of data now
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from really good quality peer-reviewed studies
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that indicate certain things that we can do,
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including certain foods that we should eat,
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and perhaps even some foods that we should avoid
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in order to enhance our brain function.
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And of course, when I say brain,
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what I really mean is nervous system function,
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because how we are able to move and remember things, et cetera
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doesn't just depend on the neurons,
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the nerve cells that are in our head,
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it also depends on our spinal cord
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and the neurons that connect to all the organs of our body.
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So in general, there are two categories of things
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that are going to improve brain health
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from the perspective of nutrition.
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The first category is the general category
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of things that we eat and avoid
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and things that we do and avoid doing
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that will modulate brain health and function.
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What do I mean by modulate?
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Well, getting quality sleep on a regular basis,
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making sure that you're socially connected,
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making sure that you're not depressed.
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All these things are vitally important
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to our overall health,
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and of course they will impact brain function,
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but they do it more or less indirectly, okay?
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There are a few things that happen in sleep
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which directly benefit brain function and repair, et cetera.
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But today I really want to concentrate
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not on the things that modulate our overall health,
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but rather the things that mediate brain health directly,
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and in particular,
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how certain foods enhance brain function.
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And we are going to talk about
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how we can change our relationship to food,
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literally how we can start to prefer certain foods
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that are better for us than others.
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I want to touch on the modulatory components
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because they are vital.
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First of all, getting quality sleep on a regular basis
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and ample sleep on a regular basis
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is the foundation of all mental health and physical health.
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There's no question about that.
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We have done several episodes,
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including the Master Your Sleep episode,
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which is episode two of the Huberman Lab Podcast,
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and we've done a lot of other episodes
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that are all about sleep and how to get better at sleeping.
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So I just want to make crystal clear
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that unless you're sleeping well on a regular basis,
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your brain will suffer.
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You won't be able to focus very well, learn very well,
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and indeed there are data linking poor quality sleep
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to dementia or at least exacerbating preexisting dementias
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and things of that sort.
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So get your sleep in order.
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The other, of course, is cardiovascular health and exercise.
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The general prescription that's out there in the literature
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and I think is well-supported
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is to get somewhere between 150 and 180 minutes
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of cardiovascular exercise per week.
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If you choose to also use resistance exercise, that's great,
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but the 150 to 180 minutes minimum per week
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of cardiovascular exercise is crucial for heart health
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and heart health directly relates to brain health
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because the brain consumes a lot of oxygen, glucose,
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and other factors that are delivered via the blood.
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So if your arteries are clogged up
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and you've got poor vascular supply to the brain
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in any region of the brain, your brain will suffer.
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So get cardiovascular health in order.
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Now, with those two modulatory elements set forth
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so that we're all aware that they're there
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and they are vitally important,
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now I'd like to turn to the elements that have been shown
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to be vitally important for directly controlling,
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for mediating neuron function.
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Neurons, of course, are nerve cells in the brain
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and there are other cell types too, of course,
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that will impact brain function.
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The most prominent of which are the so-called glia.
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Glia means glue, but even though for a long time
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people thought that these cells
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were just kind of holding things together passively,
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the glia play a very active role in the metabolism neurons,
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in brain function, and probably also in cognition,
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in thinking and so forth.
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So what are the things that directly impact brain health
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and what are the foods that we can eat
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that will support brain health?
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Generally, when we think about neuron function
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and brain function, we default to a discussion about fuel.
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The fact that neurons use glucose, which is blood sugar,
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and that they require a lot of it.
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In some cases, they'll use ketones,
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which we will talk about a little bit later,
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especially in people that are following a low carbohydrate
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or ketogenic diet.
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But before we can even consider the fuels that neurons use
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in order to function, we have to talk about the elements
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that actually allow those neurons to be there
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and to stay healthy, what actually makes up those neurons.
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And that brings us to what I would argue
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is the most important food element for brain function.
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And that might come as a surprise,
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but unless one considers the water content of the brain,
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which is very high, a lot of our brain
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and a lot of the integrity of the nerve cells,
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the so-called neurons in our brain,
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and the other types of cells comes from fat.
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And that's because nerve cells and other cells in the brain
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have a external layer.
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It's what's sometimes called a double-layered membrane.
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It's essentially two thin layers
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that serve as a boundary between those cells.
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And that boundary is very important
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because how things pass across that boundary
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actually regulates the electrical activity of neurons,
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which is the way that neurons fire and communicate
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and keep you thinking and acting
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and doing all the good things
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that those neurons allow us to do.
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And those membranes are made up of fats,
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but they're not made up of the fats
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that are around our belly,
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around the other organs of our body.
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They're not made up of storage fat.
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They are made up of structural fat
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and maintaining the so-called integrity
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of that structural fat,
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meaning the health of those neurons
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is going to come in large part from the foods that we eat.
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Now, this needs to be underscored.
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What I'm saying is that the foods that we eat
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actually provide the structural basis,
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the building blocks of the very neurons
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that allow us to think over time.
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And as I mentioned earlier,
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the fat that makes up those neurons and other nerve cells
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is different than the other types of fat in the body.
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So what type of fat is it and what should we eat
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in order to support that fat and those neurons?
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And the answer is the so-called essential fatty acids
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and phospholipids.
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Now, those are more or less the same thing,
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but I just want to make a very large literature
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very crystal clear.
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Essential fatty acids can include the so-called EPA variety
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You hear about omega-3s and omega-6s.
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Most people are getting enough omega-6s from their diet.
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Not everybody, but most people
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are getting enough omega-6s.
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However, most people are not getting enough omega-3s
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in their diet to support healthy brain function
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in the short and long term.
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I've talked before about the benefits
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of elevating the levels of omega-3s in one's diet
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for sake of offsetting depression and for enhancing mood.
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And indeed there's a wealth of literature now
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pointing to the fact that ingesting at least one or two
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or even three grams per day of EPA form
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of essential fatty acid can have effects,
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positive effects on mood and wellbeing
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that are at least on par
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with some of the major antidepressant treatments out there,
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but without similar side effects
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to those antidepressant treatments.
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And that for people that are already taking antidepressants
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that supplementing with one to two to three grams of EPA,
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essential fatty acids can actually allow a lower dose
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of antidepressant treatment to be used
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and still be effective.
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So that's depression,
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but just in terms of maintaining normal cognitive function
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in people that aren't depressed,
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the EPAs and omega-3s seem to play a very important role.
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Of course, you can supplement EPAs through various fish oils
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and it could be liquid fish oil or capsule fish oil.
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Some people, if they're not interested in eating fish
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for whatever reason, they're allergic or for ethical reasons
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they can take krill oil.
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And if they don't want to use krill oil,
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they can use algae and other forms of EPA.
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However, I think it's clear that one can get a lot of EPA
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from the proper foods.
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And it turns out that those foods, not surprisingly,
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don't just contain high levels of EPA,
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but they also contain other things
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that are beneficial for brain health.
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So what are foods that are high in omega-3s
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that we should all probably be consuming,
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at least on a daily basis?
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The number one is fish.
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So things like mackerel and salmon and herring and oysters
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and sardines and anchovies,
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and perhaps the heavyweight champion of EPAs
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per unit volume is caviar.
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Now, I don't know about you,
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but I'm not eating a lot of fish.
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I'm not eating a lot of caviar.
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I don't think, I can't remember the last time I had a caviar
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unless it was sprinkled on a little bit of sushi.
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I'm not a big fish eater personally.
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I will from time to time,
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but that's one reason why one might want to supplement
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with EPAs from another source.
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But also EPAs are found in chia seeds, in walnuts,
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in soybeans and other plant-based foods.
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You can look these up online and you'll immediately see
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that there are a lot of sources of EPAs.
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And many of the foods that I listed off
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might be appetizing to you.
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Some of them might be unappetizing to you,
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or some of them you might be sort of neutral about,
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but it's very clear that eating foods
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that are rich in omega-3s and or supplementing
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with omega-3s to get above that 1.5 grams,
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and ideally up to two or even three grams per day of EPA,
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can be very beneficial for cognitive function
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in the short and long term.
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Later in the episode, I'm going to talk about
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how to actually change your relationship
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to particular foods so that foods
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that you don't particularly like,
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you can actually start to like more.
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And that might be important for those of you
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that are thinking mackerel, sardines.
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I mean, I'm making this face because frankly,
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those are not foods that I naturally like.
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But again, I want to emphasize
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that you don't have to consume fish and animal products
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in order to get sufficient EPAs.
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You can get them from plants,
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but I do believe based on the quality peer-reviewed research
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that everybody should be striving
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to get a minimum threshold of at least a gram and a half
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of EPAs per day, one way or the other.
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The great thing about omega-3s
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is that they are also thought to be beneficial
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for things like cardiovascular health.
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And although there's some controversy there
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as to whether or not two grams or three grams or six grams
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is ideal for cardiovascular health,
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I think the bulk of evidence points to the fact
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that getting sufficient omega-3s in the diet
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is going to support cardiovascular health.
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Certainly not the only thing people should be doing
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to support their cardiovascular health,
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aerobic exercise and so forth being important also,
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but it does seem to support cardiovascular health
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and in doing so, supporting brain health.
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However, what I'm emphasizing is ingestion of omega-3s
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to support the very cells within the brain
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that make up our cognition,
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that allow for cognition and for movement and memory
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and all the other marvelous things that the brain does.
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The other compound that has been shown
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to be directly supportive of neuronal function
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is phosphatidylserine,
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which is abundant in meats and in fish.
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So here we are again, back to fish being an important source
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of brain supporting food.
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Phosphatidylserine is something that nowadays
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people are supplementing.
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It's a lipid-like compound that at least in three studies
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have been shown to improve cognition.
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These weren't huge effects,
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but they were statistically significant effects.
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And as well in more than three, at least five studies
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to reduce cognitive decline.
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And this is interesting, in every case,
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it was 300 milligrams supplemented phosphatidylserine,
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but one again, doesn't need to supplement phosphatidylserine.
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Phosphatidylserine can be derived,
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as I mentioned from meats and fish,
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and to some extent from cabbage of all things.
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I don't know how much cabbage people are ingesting,
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but later when we talk about gut health
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and the relationship between gut health and brain health,
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I'll mention fermented foods.
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one of the most readily available fermented foods out there
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that at least many people find appetizing is sauerkraut,
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which is of course made from cabbage, it's fermented cabbage.
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So for those of you that do consume meat and fish,
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provided you're getting enough fish,
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you're probably getting enough phosphatidylserine.
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For those of you that are interested
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in supplementing phosphatidylserine
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to get these effects that were reported
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in these various manuscripts,
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which by the way, I've read and looked solid.
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I mean, I don't think we've seen the landmark studies
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showing that supplementing with phosphatidylserine
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at 300 milligrams per day
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is going to create a huge offsetting
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of a massive cognitive decline
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or a massive increase in brain function.
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These seem to be modest effects,
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but the effects do appear to be real.
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And for those of you that are interested
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in supplementing with phosphatidylserine,
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it's a relatively inexpensive supplement
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that again is lipid-like.
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So it's mimicking some of the same things
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that you would get from food, but in higher concentration.
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Now, after EPA, fatty acids and phosphatidylserine,
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I would say third on the list of things that come from food
link |
that can readily support brain function would be choline.
link |
And that's because of the relationship to choline
link |
in the biosynthesis pathway for acetylcholine.
link |
Acetylcholine is a neuromodulator, not a neurotransmitter,
link |
but a neuromodulator in the brain.
link |
A neuromodulator is a chemical that modulates
link |
the function of many brain circuits
link |
and also circuits within the body.
link |
I'll mention what those are in a moment,
link |
but acetylcholine as a neuromodulator
link |
tends to enhance the activity, the electrical activity
link |
and chemical activity of certain sets of neurons
link |
and downplay the activity of other neurons.
link |
So it's sort of a conductor of sorts
link |
leading to enhanced function and activity
link |
in certain brain areas and circuits and others.
link |
For instance, the brain areas that are involved
link |
in focus and alertness.
link |
We have multiple clusters of neurons in our brain
link |
that make acetylcholine.
link |
Two of the most prominent and well-known
link |
are the so-called nucleus basalis,
link |
which is a cluster of neurons deep in the basal forebrain
link |
that highlight particular areas of our brain,
link |
highlight meaning when acetylcholine is released
link |
from those neurons at their nerve endings
link |
in particular areas of the brain,
link |
those particular areas of the brain
link |
can undergo enhanced levels of activity
link |
relative to surrounding area.
link |
So it's kind of a electrical highlighter pen, if you will,
link |
That is the basis of much of what we call focus
link |
or our ability to concentrate on a particular batch
link |
of information that's coming in through our eyes,
link |
our ears, our nose,
link |
or even things that we're just thinking in our head.
link |
So having ample choline for production of acetylcholine
link |
allows for focus through, of course, many intervening steps.
link |
There are also regions of the brain
link |
in the so-called back of the brain, the hindbrain,
link |
that release acetylcholine
link |
that are involved in general states of alertness.
link |
And not surprisingly then,
link |
many of the treatments for Alzheimer's disease,
link |
which is an inability or challenges
link |
with remembering things and focusing
link |
are drugs that impact the acetylcholine pathway
link |
and are aimed at enhancing the amount of acetylcholine
link |
that's available to neurons.
link |
And it can do that through a number of different mechanisms.
link |
You can do that by enhancing the amount of acetylcholine
link |
or you can do that by taking a drug
link |
that can reduce the amount of enzyme
link |
that gobbles up the acetylcholine
link |
and in doing so leading to more net acetylcholine.
link |
But outside of the scenario
link |
where somebody has cognitive decline due to Alzheimer's,
link |
all of us are able to focus to some degree or not,
link |
or are able to be alert to some degree or not
link |
based on the amount of acetylcholine that we have.
link |
Now, other processes of course are involved,
link |
but what this means is that making sure
link |
that we have enough of the substrates
link |
to create acetylcholine is vital
link |
if we want to be able to focus.
link |
And that's why dietary choline is so vital.
link |
And the primary source for dietary choline
link |
would be eggs and in particular egg yolks.
link |
And this again has a very interesting relationship
link |
to our evolution as well.
link |
We're always referred to as hunter-gatherers,
link |
but when one hears hunters,
link |
we often think about meat and animal sources.
link |
And indeed, as a species,
link |
we hunted many, many other species of animals
link |
to consume them and still do.
link |
But we also fished, we talked about that earlier
link |
and consumed a lot of fish and we consumed a lot of eggs.
link |
Eggs are an incredibly rich source
link |
of nutrients for the brain.
link |
And that's because the egg actually,
link |
if you think about it,
link |
contains all the nutrients that are required
link |
in order for an organism to grow.
link |
A bird that's in a egg shell, it's got the yolk there
link |
and it's using that yolk for a reason.
link |
It's using that yolk as a source of fuel.
link |
It's using that yolk as a source of literally building blocks
link |
in order to create its nervous system.
link |
Many years ago, I worked on chick embryos.
link |
And as these amazing experiments,
link |
you could actually take an egg
link |
and you could create a little window in the top.
link |
And these were fertilized eggs and you'd see over time,
link |
you could peer in there, literally look in with a microscope
link |
or even with the naked eye
link |
and you would see this little chick embryo
link |
sitting on top of that yolk growing and growing
link |
and growing and growing
link |
and the yolk getting smaller and smaller
link |
is really incredible.
link |
They're using that as a source
link |
for all the building blocks of the body,
link |
but in particular, the nervous system.
link |
So eggs are a rich source of choline.
link |
Some people will supplement with choline.
link |
However, food sources seem to be the best source of choline.
link |
And as with the EPAs and the omega-3s,
link |
there are plenty of foods that are non-animal based
link |
that contain choline.
link |
So if you're somebody who doesn't eat eggs
link |
or doesn't want to eat eggs,
link |
things like potatoes, nuts and seeds and grains and fruit,
link |
they don't have as much choline as eggs,
link |
but they do contain choline.
link |
So you can look up the values of choline
link |
that are present in those various foods
link |
and make sure that you're reaching the threshold
link |
amount of choline for you.
link |
In general, most people should probably strive
link |
to get somewhere between 500 milligrams
link |
and a gram of choline per day.
link |
So a thousand milligrams.
link |
And some people rely on supplementation
link |
in order to hit those levels
link |
because they're not eating a lot of egg yolks
link |
or they're not eating a lot of other foods.
link |
Certain fish contain choline, for instance,
link |
and the other foods I listed off a few minutes ago
link |
from plant-based sources.
link |
So some people will supplement with 50 to 100 milligrams
link |
or whatever amount is necessary to get them
link |
up to that one gram or even a two gram dose per day.
link |
So we have three things that we know can support nerve cells.
link |
EPA, in particular, omega-3 fatty acids,
link |
phosphatidylserine, and choline.
link |
Those three things I would list off as the top three things
link |
for enhancing neuron function and the integrity of neurons
link |
in the short and long term.
link |
And this is, again, is setting aside
link |
the vitally important factors of hydration
link |
I've said it before on other podcasts,
link |
but if you're not ingesting enough water
link |
and you're not getting enough sodium
link |
and magnesium and potassium,
link |
then obviously your neurons can't run
link |
because a lot of the brain is water.
link |
You need to maintain proper hydration
link |
and sodium, potassium, and magnesium are important
link |
in order for nerve cells to function.
link |
In fact, they are actually the components,
link |
the ions that pass across those lipid membranes,
link |
those little fatty membranes
link |
that we were talking about earlier
link |
that allow the neurons to generate electrical activity
link |
and communicate with one another.
link |
So definitely you want to hydrate enough.
link |
We will do an entire other episode
link |
all about hydration and electrolytes,
link |
but omega-3s, the EPAs, phosphatidylserine, and choline,
link |
it's obvious, are going to improve brain function.
link |
How much they will improve brain function
link |
probably depends on how well
link |
your brain was working previously.
link |
In fact, many of the studies that have looked
link |
at the effectiveness of these compounds
link |
have looked in people that are suffering from mild
link |
or even severe cognitive decline.
link |
And while the outcomes of those studies vary,
link |
given the interest in maintaining brain function,
link |
given the fact that we don't make new neurons
link |
throughout our entire life,
link |
and given that everybody has to eat,
link |
these are quality, healthy foods
link |
that we should all be ingesting anyways,
link |
and it's clear that they can support brain function
link |
to some degree or another.
link |
Many people ask what I do in light of this information.
link |
And while I can only talk about what works for me,
link |
I choose to ingest fish oil, mainly in liquid form,
link |
because that turns out to be the easiest way
link |
and the most economically affordable way to do it
link |
So there are various forms of liquid fish oil out there.
link |
Some of them include some lemon flavoring,
link |
so it doesn't taste like fish oil,
link |
because frankly, fish oil to me is sort of noxious tasting.
link |
And I'll take a tablespoon of that or two per day.
link |
If I'm traveling, I'll use the capsule form
link |
in order to hit that threshold of, for me,
link |
about two, sometimes even three grams per day of EPA.
link |
So not just two or three grams per day of fish oil,
link |
but two or three grams per day of EPA.
link |
Now, if I'm eating fish,
link |
which as I mentioned earlier is not often,
link |
then I might reduce the amount of fish oil that I take,
link |
but that's my major source of fish oil.
link |
Currently, I do not supplement with phosphatidylserine.
link |
A number of people that I know and trust,
link |
and indeed several colleagues of mine
link |
do take phosphatidylserine.
link |
I don't have any good explanation
link |
for why I don't take it yet,
link |
but I have not tried supplementing with it yet.
link |
Maybe if some of you have,
link |
you can place your experience in the comment section.
link |
That would be of interest.
link |
And then in terms of choline,
link |
in order to get choline in my diet,
link |
I do pay attention to the various foods that contain choline
link |
and I try and get those foods on a semi-regular basis.
link |
I do supplement with something called alpha-GPC,
link |
which is essentially in the acetylcholine pathway
link |
or biosynthesis pathway.
link |
I don't take it very often,
link |
but I will take 300 milligrams of alpha-GPC
link |
from time to time.
link |
From time to time,
link |
I mean anywhere from two to three times per week.
link |
I'll generally do it early in the day
link |
because it, for me,
link |
can have a little bit of a stimulant effect,
link |
although it's not nearly as stimulating, say,
link |
as a double espresso or triple espresso.
link |
But that's one way in which I enhance my choline function.
link |
And some people choose to get it from supplementation
link |
because it's straightforward.
link |
There are a lot of supplements out there
link |
that contain alpha-GPC.
link |
Some people are taking dosages
link |
as high as 900 milligrams per day.
link |
That sounds very high to me.
link |
The studies of offsetting cognitive decline
link |
using alpha-GPC did use quite high dosages
link |
of 600 to 900 or even 1200 milligrams per day.
link |
So it has been used at those much higher concentrations,
link |
but because fortunately,
link |
at least not yet or not to my awareness,
link |
I'm not suffering from any cognitive decline,
link |
I will supplement with 300 milligrams every now and again.
link |
Next on my list of compounds that have been shown
link |
in peer-reviewed research
link |
to improve neuronal and brain function is creatine.
link |
Creatine can be derived from meat sources.
link |
It can also be supplemented.
link |
Some of you are probably familiar with creatine
link |
or have heard about creatine
link |
from the context of the health and fitness world
link |
where creatine is used to bring more water into muscles,
link |
which can enhance the strength of those muscles,
link |
as well as bring water into other tissues.
link |
So it doesn't just draw more water into muscle,
link |
it can draw more water into the body generally.
link |
Creatine has also been shown to have an important role
link |
in brain function.
link |
And once again, this is something that came up
link |
during the discussion about depression a few episodes back.
link |
Creatine can actually be used as a fuel source in the brain.
link |
And there's some evidence that it can enhance the function
link |
of certain frontal cortical circuits that feed down onto,
link |
or rather connect to areas of the brain
link |
that are involved in mood regulation and motivation.
link |
And that's where creatine plays a role in depression,
link |
or rather where creatine supplementation
link |
seems to be able to assist in some forms of mild depression.
link |
That's an emerging literature.
link |
It's still not well-established.
link |
However, there is now ample evidence
link |
that creatine supplementation can enhance brain function
link |
in certain contexts.
link |
And if you're interested in learning more
link |
about what those contexts are,
link |
there's an excellent review that just came out,
link |
the first author is Rochelle, R-O-S-C-H-E-L.
link |
We will provide a link to this study,
link |
rather this review, excuse me, in the caption.
link |
This was published just very recently in 2021.
link |
And one thing to make clear is that creatine supplementation
link |
has been shown to be especially useful
link |
for people that are not consuming any meat
link |
or other sources of foods that are rich in creatine.
link |
What is the threshold level of creatine to supplement
link |
in order to get the cognitive benefit?
link |
Appears to be at least five grams per day.
link |
Now, the most typical form of creatine
link |
is so-called creatine monohydrate.
link |
There are other forms of creatine as well,
link |
some of which are thought to not draw as much water
link |
into non-muscle tissues.
link |
And for some people that that's attractive to them,
link |
they don't want water sitting below their skin, et cetera.
link |
I should emphasize that the responses to creatine
link |
in that sense can differ.
link |
Some people get a little bit of water retention.
link |
Some people experience more.
link |
There's some evidence that creatine can impact
link |
some of the hormonal pathways
link |
that it might enhance levels
link |
of so-called dihydrotestosterone, DHT.
link |
And therefore, because DHT is involved in hair loss,
link |
there are these theories that creatine can cause hair loss.
link |
And indeed, for people that are very DHT sensitive,
link |
it might, you know,
link |
there's going to be a lot of variation person-to-person
link |
in terms of how much creatine impacts DHT
link |
and how many DHT receptors they have on their scalp
link |
and therefore whether or not they experience hair loss.
link |
I'm just giving you all this information
link |
so that you're aware of the various things
link |
that creatine can do.
link |
But nonetheless, I think it's interesting
link |
that creatine supplementation of five grams per day,
link |
that's creatine monohydrate,
link |
has been shown to improve cognition
link |
in people that aren't getting creatine from animal sources.
link |
And there's some evidence detailed within the review
link |
that I just described
link |
that creatine supplementation can also enhance cognition
link |
in people that are also eating animal products.
link |
So I personally take creatine five grams per day
link |
and have for a very long time.
link |
I can't say that I've noticed a tremendous benefit
link |
because I've actually never really come off it.
link |
And so I've never done the control experiment.
link |
I take it more as kind of a baseline insurance policy.
link |
For me, I'm probably losing,
link |
I'm certainly losing some of my hair,
link |
whether or not that's due to creatine or not.
link |
I've never done the analysis.
link |
But what I can say is that I generally consume these things
link |
like EPAs, creatine, alpha-GPC,
link |
to set a general context of support for my neurons,
link |
And of course, I also pay attention to the foods
link |
that contain these various compounds.
link |
So I don't actively eat additional meat
link |
just to obtain creatine.
link |
I eat a fairly limited amount of meat.
link |
I don't restrict it, and I do eat meat,
link |
but I don't actively seek out creatine in my diet.
link |
Rather, I use supplementation
link |
in order to hit that five grams per day threshold.
link |
Next on the list of foods that are beneficial
link |
for brain health is one that you've probably seen pictures
link |
of online because there seems to be a practice
link |
of putting pictures of blueberries and other dark berries
link |
next to any title that says foods that benefit your brain.
link |
There are a lot of foods out there
link |
that have been purported to improve brain function.
link |
The interesting thing about blueberries and other berries,
link |
blackberries, dark currants,
link |
any of these thin-skinned berries that are purplish in color
link |
is that they contain what are called anthocyanins.
link |
Anthocyanins actually have some really nice data
link |
to support the fact that they improve brain function.
link |
Now, whether or not it is direct effects on neurons
link |
or whether or not it is by lowering inflammation
link |
or some other modulatory effect isn't quite clear,
link |
but I think by now there's enough data to support the fact
link |
that eating a cup or two of blueberries pretty often,
link |
every day, or maybe you have blackberries
link |
or maybe it's black currants,
link |
that these anthocyanins are good for us,
link |
that they are enhancing our overall wellbeing
link |
at a number of different levels.
link |
And just to give you a couple of examples
link |
of where there are actually peer-reviewed studies
link |
to support those statements,
link |
the anthocyanins of which blueberries
link |
and other dark berries are rich in
link |
have been shown to reduce the amount of DNA damage,
link |
has been shown to reduce significantly,
link |
albeit slightly, excuse me, cognitive decline.
link |
And that particular study was supplementation
link |
of a blueberry extract.
link |
I'll talk about the difference between extract
link |
and actual blueberries in a moment,
link |
but supplementation of blueberry extract
link |
in offsetting cognitive decline in elderly people.
link |
So, you know, what constitutes elderly
link |
is always a little bit of a debate and a discussion,
link |
but in this case, what they did is they supplemented
link |
with somewhere between 428,
link |
I don't know why they selected 428,
link |
and 598 milligrams of anthocyanins daily for 12 weeks
link |
was associated with improvements
link |
on verbal learning and memory.
link |
And they had some other beneficial changes
link |
that were within the bodily organs
link |
and blood glucose regulation and so forth, positive changes.
link |
But that's one study.
link |
In this case, elderly meant 65 or older.
link |
That study and a number of studies like it,
link |
looking at things like mildly enhanced memory,
link |
reduced insulin levels, reduced oxidation of LDL,
link |
these sorts of things have basically created a situation
link |
where anytime you Google or look up foods
link |
that enhance brain function,
link |
you're going to see a picture of a blueberry
link |
or some other berry because of these anthocyanins.
link |
I personally don't supplement anthocyanins.
link |
I do like blueberries.
link |
I eat blueberries when they're in season.
link |
I'm what you would call a drive-by blueberry eater.
link |
Like if there are blueberries in a bowl on a table
link |
and I'm walking by, I just have to scoop them up
link |
like some sort of bear or other animal
link |
and pop them in my mouth.
link |
So blueberries don't last long around me.
link |
One of the issues with berries,
link |
like blueberries and blackberries and so forth
link |
is that quality sources of them can be pretty expensive.
link |
And then of course, when they're not in season,
link |
they're hard to get.
link |
And so that's why some people will supplement with them.
link |
So that range of about 400 to about 600 milligrams per day,
link |
seems to be the minimum threshold
link |
for getting a cognitive effect in these elderly patients.
link |
In that case, they were patients.
link |
A good review about the anthocyanins
link |
potentially contributing to offsetting cognitive decline
link |
in things like Alzheimer's
link |
and also enhancing brain function
link |
in people that don't have Alzheimer's
link |
is a review by Afzal, A-F-Z-A-L,
link |
that was published in 2019.
link |
We will also provide a link to that study in the caption.
link |
When one looks across the total batch of studies
link |
that are out there on this,
link |
it appears that if one is going to supplement
link |
with blueberry extract
link |
to get the anthocyanin effect on cognition,
link |
dosages of somewhere between five and a half
link |
or about 11 grams seem optimal with the higher end,
link |
closer to 10 or 11 grams being more beneficial.
link |
The blueberry eaters out there like me
link |
who prefer to get their anthocyanins from the actual berries,
link |
it appears that somewhere between 60 to 120 grams
link |
of fresh blueberries each day
link |
is the way that you can get sufficient anthocyanins
link |
to at least shift your system or bias your brain
link |
towards these enhanced cognitive effects.
link |
So we've got EPA fatty acids,
link |
we've got phosphatidylserine, we've got choline,
link |
we've got creatine, and we have the anthocyanins.
link |
And the last item that I'd like to place
link |
in this list of food-derived things
link |
that can enhance brain function is glutamine.
link |
Glutamine is a very interesting amino acid.
link |
I've talked about glutamine on here before.
link |
There's some evidence, although somewhat scant,
link |
there's some evidence that glutamine
link |
can enhance immune system function.
link |
So people will supplement with glutamine
link |
or people can get glutamine from foods.
link |
Foods that contain a lot of glutamine
link |
are things like cottage cheese.
link |
There are also other sources of glutamine.
link |
Glutamine is rich in protein-rich foods,
link |
things like beef, chicken, fish, dairy products, eggs,
link |
but also for you non-animal food-consuming people out there,
link |
vegetables, including beans, cabbage once again,
link |
spinach, parsley, things of that sort.
link |
So those foods contain glutamine.
link |
For people that supplement with glutamine,
link |
generally they will take anywhere from a gram
link |
as much as 10 grams per day.
link |
Why would they want to do that?
link |
Well, there's also some evidence starting to emerge
link |
that glutamine can help offset sugar cravings.
link |
And I've talked about this on the podcast before.
link |
We're going to talk more about the basis for this
link |
a little bit later.
link |
But in brief, we all have neurons in our gut
link |
that sense the amino acid content, the fat content,
link |
and the sugar content of the foods that we eat
link |
and signal in a subconscious way to our brain
link |
whether or not the foods that we are eating
link |
contain certain levels of certain amino acids.
link |
And so we actually have glutamine-sensing neurons
link |
in our gut that actually have their little processes,
link |
their little axons and dendrites as we call them
link |
in the mucosal lining of the gut.
link |
They're not just sensing glutamine,
link |
but when they do sense glutamine, they respond
link |
and they send signals to the brain
link |
that are signals of satiation, of satisfaction.
link |
And in doing so can offset some of the sugar cravings
link |
that many people suffer from.
link |
Now, here we're talking about glutamine
link |
for sake of enhancing cognitive function.
link |
And this is interesting because it's been shown
link |
that glutamine supplementation can offset
link |
some of the negative effects on cognition caused by altitude
link |
and oxygen deprivation of other sorts.
link |
Well, that's kind of a strange and unique situation
link |
if you're going up to altitude,
link |
should you supplement with glutamine
link |
in order to be able to think more clearly?
link |
Well, it appears that there's good rationale for doing that.
link |
But the reason I bring this up,
link |
assuming that most people, including me,
link |
are not going up to high altitudes very often,
link |
is that it's been well-established
link |
that apnea, failure to breathe properly during sleep,
link |
can contribute to age-related
link |
and even non-age-related cognitive decline.
link |
There are a lot of reasons for apneas,
link |
ranging from obesity to obstruction of the airways
link |
for other reasons.
link |
There are a tremendous number of underlying causes of apnea
link |
and it's something to be taken seriously.
link |
I mean, heart attacks,
link |
all sorts of metabolic issues are caused by apnea.
link |
Apnea is a serious issue that disrupts the depth of sleep
link |
and it's a serious health issue in general.
link |
In any event, apnea is associated with cognitive decline
link |
and cognitive dysfunction, even in young people.
link |
And it does appear that glutamine supplementation
link |
can offset some of the cognitive deficits
link |
that are associated with reduced oxygenation of the brain.
link |
If you'd like to learn more about how apnea
link |
can negatively impact cognition,
link |
there's an excellent paper
link |
that was published on this in 2018.
link |
The first author is Sharma, S-H-A-R-M-A.
link |
It should be easy to find.
link |
The title of the paper is
link |
Obstructive Sleep Apnea Severity Effects Amyloid Burden
link |
in cognitively normal elderly.
link |
This was a longitudinal study.
link |
Amyloid burden is a correlate of Alzheimer's
link |
and other forms of neurodegeneration and cognitive decline
link |
associated with memory deficits.
link |
So obstructive sleep apnea, excuse me,
link |
is a very serious issue for which glutamine appears
link |
to be able to offset some of the negative symptomology.
link |
So how is it that glutamine,
link |
either from food or through supplementation,
link |
can offset some of these so-called hypoxic effects
link |
caused by sleep apnea,
link |
hypoxia being a lack of oxygen for the brain
link |
that relate to cognitive decline.
link |
It appears to have this positive impact
link |
by way of reducing inflammation.
link |
So if you want to look more deeply
link |
into the various biological pathways
link |
and the supplementation regimes for this,
link |
the paper that I think is really spectacular is a paper.
link |
Last author is Quaresma, Q-U-A-R-E-S-M-A.
link |
That's Q-U-A-R-E-S-M-A.
link |
the possible importance of glutamine supplementation
link |
to mood and cognition in hypoxia from high altitude.
link |
And even though the paper is about
link |
high altitude induced hypoxia,
link |
it does seem to have direct relevance
link |
to the sorts of apnea that are related to Alzheimer's
link |
and other forms of cognitive decline.
link |
Now I've been taking glutamine as a supplement, gosh,
link |
since I was in college,
link |
mostly because I felt either by superstition or by reality
link |
that it protected me from various flus and colds
link |
and things of that sort
link |
because of the purported immune enhancing effects.
link |
Again, those immune enhancing effects
link |
have some data to support them, not a ton.
link |
However, I got into the habit of taking glutamine
link |
and now that I've learned that glutamine
link |
seems to also have some cognitive enhancing effects,
link |
possibly, it's a supplement that I continue to take.
link |
I take very small amounts of it,
link |
but I do take it on a regular basis.
link |
So that more or less completes the list of things
link |
that at least by my read of the literature
link |
are things that are supported by at least three
link |
and in some cases, as many as hundreds of studies
link |
in various populations
link |
that have been explored in mouse studies often,
link |
but also in a number of human studies.
link |
I want to emphasize again,
link |
that all of the things I listed out,
link |
whether or not it's EPAs,
link |
whether or not it's phosphatidylserine,
link |
whether or not it's choline,
link |
whether or not it's the various compounds
link |
that are in berries, et cetera,
link |
all of those can be extracted from food.
link |
There is not any law that says
link |
that you have to get them from supplementation.
link |
Supplementation can help you get to the very high levels
link |
of those things if you want to work on the higher end,
link |
if that's right for you,
link |
obviously check with your doctor before taking anything
link |
or removing anything from your diet or supplement regime.
link |
But in general, you can get these things from foods.
link |
It's just so happens that for some of these compounds,
link |
the foods that they're contained in like fish
link |
are not foods that I particularly enjoy.
link |
And so I rely on, excuse me,
link |
I rely on supplements in order
link |
to get sufficient levels for me.
link |
But again, you can get these levels from food.
link |
And the reason I made this list,
link |
the reason that I emphasize these things
link |
in this particular order is that they support
link |
the structure of neurons.
link |
They support the structure of the other cells of the brain
link |
that make up our cognition
link |
and that are important for our focus
link |
and our ability to remember things and so forth.
link |
And they are less so in the category
link |
of so-called modulatory effects.
link |
They will also have modulatory effects on sleep,
link |
on inflammation or reducing inflammation
link |
throughout the body, on cardiovascular function,
link |
all of which I believe are positive effects,
link |
at least what the literature tells us
link |
is that none of these compounds
link |
are harming other systems of the body
link |
provided they are taken at a reasonable levels.
link |
But everything in this list is directed
link |
towards answering the question, what can I eat?
link |
What can I ingest by way of food and or food supplement
link |
that can support brain function
link |
in the short-term and in the long-term?
link |
So I hope you find that list beneficial for you,
link |
if not for use, at least for consideration.
link |
So now having talked about some of the foods
link |
and micronutrients that are beneficial
link |
to our immediate and long-term brain health,
link |
I'd like to shift gears somewhat
link |
and talk about why it is that we like the foods that we like.
link |
We've all heard before that we are hardwired
link |
to pursue sugar and to like fatty foods
link |
and that calorie-rich foods are attractive to us
link |
for all sorts of reasons,
link |
surviving famines and things of that sort.
link |
And while that is true,
link |
the actual mechanisms that underlie food seeking
link |
and food preference are far more interesting than that.
link |
There are basically three channels
link |
in our body and nervous system
link |
by which we decide what foods to pursue,
link |
and whether or not we will find a particular food attractive,
link |
whether or not we will want to consume more of it,
link |
whether or not we want to avoid it,
link |
or whether or not it's just sort of so-so,
link |
what I refer to as the yum, yuck, or meh analysis.
link |
And indeed, that's what our nervous system is doing
link |
with respect to food.
link |
It's trying to figure out whether or not yum,
link |
I want more of this,
link |
yuck, I want to avoid this,
link |
or meh, it's so-so.
link |
Now, while that may seem like a overly simplified version
link |
of food seeking and food preference,
link |
it's actually not that far from the truth.
link |
It actually correctly captures much of the biology
link |
of food preference.
link |
So let's talk about what these three channels
link |
for food preference are.
link |
The first one is an obvious one.
link |
It's taste on the mouth.
link |
It is the sensation that we have of the foods
link |
that we eat while we're chewing them.
link |
And those sensations,
link |
which are literally just somatosensory touch sensations,
link |
you know, the palatability of food
link |
as it relates to the consistency of food.
link |
And as you've all heard before,
link |
we have sensors on our tongue and elsewhere in our mouth
link |
that detect the various chemicals contained within food
link |
and lead to the senses of taste,
link |
which we call bittersweet, umami, salty, and sour.
link |
Now, most of us are familiar with the sense of bitterness
link |
that comes from something like a raw radish,
link |
sweet, which comes obviously from sugars of different kinds,
link |
fructose, glucose, et cetera,
link |
salty, salty, and sour.
link |
Think lemon or lemon juice, for instance.
link |
And then I mentioned umami.
link |
The umami receptor is a receptor that responds
link |
to the savory taste of things.
link |
So that's what you might find
link |
in a really wonderfully rich tomato sauce
link |
for those of you that eat meat and like meat,
link |
a really well-cooked, not necessarily well done,
link |
but properly cooked, I should say, steak,
link |
if that's your thing.
link |
And umami is present in both plant and animal foods
link |
and gives us that sensation of savoriness.
link |
It almost has a kind of little bit of a briny taste to it
link |
or braised taste to it.
link |
And indeed, braising of meats and braising of vegetables
link |
is done specifically to activate that umami receptor.
link |
So we have those five basic tastes.
link |
Those are chemical sensors on the tongue
link |
that what we call transduce those chemicals,
link |
those chemicals literally in food bind to those receptors,
link |
and it is transduced,
link |
meaning the binding of those chemicals to the receptors
link |
is converted into an electrical signal
link |
that travels in from the tongue
link |
along what's called the gustatory nerve,
link |
the gustatory nerve, then synapses,
link |
meaning it makes connections in our brainstem,
link |
in the so-called nucleus of the solitary tract.
link |
There are other nuclei back there.
link |
Nuclei are just aggregates of neurons.
link |
And then it sends information up
link |
to the so-called insular cortex, to the insula.
link |
I want to highlight the insula this episode
link |
because we are going to return to the insula
link |
again and again in this episode and later.
link |
The insular cortex is a incredible structure
link |
that we all have that mainly is concerned
link |
with so-called interoception,
link |
or our perception of what's going on inside our body.
link |
So it could be the amount of pressure in our gut
link |
because of how much food we've eaten.
link |
It could be the acidity of our gut
link |
if we're having a little bit of indigestion, for instance.
link |
It can also be the case that neurons within the insula
link |
are paying attention to how stressed you are
link |
or how alert you are or how tired you are.
link |
So it's really an inward focusing structure.
link |
It focuses on how we feel internally.
link |
And not surprisingly, the taste system sends information
link |
up to the insular cortex to give us a sense, literally,
link |
of what we've ingested,
link |
whether or not what we're tasting tastes good or not.
link |
We will return to insular cortex in a few moments.
link |
A very important thing to understand is that the neurons
link |
in the areas of the cortex, your cortex and mine,
link |
that respond to particular tastes
link |
are providing an internal representation
link |
of an external sense.
link |
What do I mean by that?
link |
I don't want to be at all abstract.
link |
We take these foods, we break them down in our mouth
link |
by chewing them or sucking on them,
link |
whatever it is the food happens to be.
link |
Those chemicals bind to those receptors
link |
and electrical signals are sent into the brain,
link |
but they are just electrical signals,
link |
just like notes being played on the keys of a piano.
link |
There's no unique signature for salty or sweet.
link |
It is the relative activation of one set of neurons
link |
that was activated by sweet,
link |
or another set of neurons that was activated by umami.
link |
It's that relative activation traveling into the brain
link |
in essentially the same form, the same electrical signals.
link |
This is really incredible, right?
link |
Electrical signals are sent into the brain and you say,
link |
aha, that's sweet and I want more of it,
link |
or that's bitter or I want less of it,
link |
or that's umami flavored and I really, really like that,
link |
really like savory foods as I happen to.
link |
That should immediately strike you as incredible
link |
because it means that your representation
link |
of what you want more of or less of is electrical in nature.
link |
And to really tamp this issue down,
link |
studies that were done by Charles Zucker, Z-U-K-E-R,
link |
he's a absolutely phenomenal neuroscientist
link |
at Columbia University in New York.
link |
Studies done by the Zucker lab have shown that,
link |
first of all, they could identify the neurons
link |
in the cortex, deep in the brain,
link |
that respond to a sweet taste or to a bitter taste.
link |
It turns out they are non-overlapping populations of neurons.
link |
And then using some molecular tricks,
link |
they were able to either silence or activate the neurons
link |
that, for instance, respond to sweet.
link |
When they do this, they see incredible consequences
link |
on perception that indeed occur in your brain
link |
and my brain as well all the time
link |
without these kinds of manipulations.
link |
Here's the experiment.
link |
They have a subject drink water that contains sugar
link |
or drink water that contains a salty substance
link |
or drink water that contains a bitter substance,
link |
for instance, okay, I'm sort of paraphrasing
link |
a large amount of work.
link |
They identify the neurons that respond to sweet tastes.
link |
They see, as many researchers have seen,
link |
that subjects prefer sweet taste to other tastes
link |
and certainly sweet taste to bitter
link |
or sweet taste to nothing, so to plain water.
link |
And then they go in and they are able
link |
to selectively silence the neurons that represent sweet.
link |
And when they do that, they eliminate the preference
link |
for that sweet taste.
link |
Now, that might seem obvious.
link |
The neurons respond to sweet.
link |
You silence those neurons.
link |
They no longer seek out sweet.
link |
But that should strike you also as incredible
link |
because they're not actually changing
link |
what's happening on the tongue
link |
or in the deeper layers of the brain.
link |
Conversely, they can have subjects drink bitter water
link |
or plain water while activating,
link |
selectively activating the neurons that respond to sweet.
link |
And what they find is that then subjects
link |
will actively prefer bitter or plain water
link |
to actual preferences such as sweet.
link |
So what this means is that your perception
link |
of what you like is a central,
link |
meaning deep within the brain, phenomenon.
link |
It's not about how things taste on your mouth.
link |
Now, of course, under normal conditions
link |
where there aren't these experimental manipulations
link |
being done, those things are positively correlated.
link |
Sweet tastes trigger the activation of sweet neurons,
link |
for instance, neurons in the mouth that respond to umami
link |
trigger the activation of neurons in the brain
link |
that respond to umami and so forth.
link |
So they're correlated in a way that makes you seek out
link |
the things that you like and avoid the things
link |
that you don't like.
link |
But as we'll see in a few minutes,
link |
turns out that that is not a direct relationship
link |
that is hardwired.
link |
You can actually uncouple the preference
link |
for particular tastes with the reward systems in the brain
link |
in a way that, for instance, would allow you to eat,
link |
or I should use myself as an example
link |
because I don't particularly like fish.
link |
I've had a few meals that include a fish
link |
that were pretty good, but none of them were memorable
link |
in the kind of positive way,
link |
like some other events in my life are memorable.
link |
But by way of these circuitries and the way they link up
link |
with one another, it's actually possible to rewire
link |
one's sense of taste and preference for particular foods.
link |
If this is seeming at all vague to you,
link |
just hang in with me a little bit longer
link |
because I will provide you with the information,
link |
tools, and resources with which to navigate this process.
link |
But the most important thing to understand is that
link |
like with our hearing, like with vision,
link |
like with smell, taste is an internal representation
link |
that has particular goals for you.
link |
Your sense of what tastes good is related
link |
to particular things that are occurring
link |
in your brain and body and that are likely
link |
to give your brain and body the things that it needs.
link |
It is not simply a matter of what you quote unquote like
link |
or what tastes good or what doesn't taste good.
link |
Let me give you a relatively simple example
link |
of how your body and your brain are acting
link |
in a coordinated way to make you prefer certain foods
link |
and indeed to pursue certain foods more.
link |
So I just mentioned you have neurons on your tongue
link |
that respond to different tastes,
link |
but of course your digestive tract isn't just your tongue,
link |
it's also your throat, it goes all the way down
link |
to your stomach and of course your intestines.
link |
Here's a long tube of digestion.
link |
All along that tube, there are neurons.
link |
Some of the neurons are responding to the mechanical size
link |
of whatever portion of the digestive tract it happens to be.
link |
So for instance, how distended or empty or full rather,
link |
and it doesn't have to be distended,
link |
depends on how much you ate,
link |
but how full or empty your gut happens to be,
link |
whether or not something you just ate is temperature hot,
link |
you know, is hot in the sense of hot to the touch,
link |
or whether or not it's spicy hot,
link |
whether or not it's soothing,
link |
whether or not it's kind of hard to swallow,
link |
this kind of thing.
link |
So you have neurons all along your gut
link |
that are responding to the mechanics
link |
related to food and digestion,
link |
and that are related to the chemistry of food and digestion.
link |
There's a population of neurons, nerve cells in your gut
link |
that are exquisitely tuned to the chemistry
link |
of whatever it is in your gut.
link |
And these are neurons called neuropod cells.
link |
They were discovered many, many years ago,
link |
but really defined and classified with modern tools
link |
I hope I'm pronouncing your name correctly, Diego.
link |
We've spoken many times,
link |
but I can't ever seem to quite capture
link |
the proper pronunciation just right.
link |
But Diego Borges at Duke University,
link |
who discovered that these cells reside within the gut
link |
and place little processes,
link |
they're little axons and dendrites
link |
within the mucosal lining of the gut.
link |
And there they are paying attention to,
link |
meaning they respond to amino acids, sugars,
link |
So as your food is digested,
link |
as food lands within your gut,
link |
neurons there are sensing what types of foods are available
link |
and what types of things are making their way
link |
through the gut environment.
link |
Now, those neurons aren't actually taking those foods
link |
and doing much with them.
link |
What they're doing is they're essentially surveying
link |
what qualities of food are there.
link |
And these particular neurons
link |
that Diego and his group discovered
link |
send electrical signals up into the brain
link |
through a little passage that we call the nodos ganglion.
link |
The nodos ganglion is a cluster of neurons
link |
that then go send up their own process into the brain
link |
and trigger the release of dopamine,
link |
which is a molecule that inspires motivation,
link |
reward, and more seeking for whatever it is
link |
led to their activation.
link |
These are super interesting neurons
link |
because what they're essentially doing
link |
is they are providing a subconscious signal
link |
about the quality of the food that you're eating,
link |
and then triggering the release of a molecule
link |
within your brain, dopamine,
link |
that leads you to go seek more of those foods.
link |
Now, this has profound impact on a number of things.
link |
First of all, there's the consideration
link |
of so-called hidden sugars.
link |
Dr. Robert Lustig, who's a pediatric endocrinologist
link |
at University of California, San Francisco,
link |
has been among the most prominent researchers
link |
to talk about the fact that there are
link |
the so-called hidden sugars in foods.
link |
Now, these are not just sugars that they sneak in
link |
just to be sneaky.
link |
These are sugars that are literally snuck in
link |
in a way that you can't taste them.
link |
That's why they're called hidden sugars.
link |
It's not that they just put them in there for fun.
link |
These are sugars that are placed into processed foods
link |
that are designed to trigger activation of these mechanisms
link |
to lead you to want to eat more of these foods,
link |
but not because they necessarily taste sweet or delicious,
link |
but because they are activating
link |
these subconscious mechanisms that are driving you
link |
to pursue more of these foods.
link |
Sounds like a very diabolical strategy.
link |
And indeed, it is somewhat of a diabolical strategy.
link |
However, these neurons are also involved
link |
in signaling to your brain when, for instance,
link |
you are eating a food that is rich in omega-3 fatty acids,
link |
the fatty acids that we were talking about earlier.
link |
So why is it that you don't crave salmon?
link |
Why is it that I don't sit around
link |
daydreaming about mackerel?
link |
Well, because there's also the influence
link |
of the actual taste on the mouth.
link |
Under normal conditions, it's a combination
link |
of the taste of the thing on the mouth
link |
plus the subconscious signaling from the gut.
link |
And while this isn't a discussion about gut microbiome,
link |
I should just mention that it's very clear
link |
that having a healthy gut microbiome
link |
allows these neurons to function in a way
link |
that serves our seeking of healthy foods in positive ways.
link |
And without getting into a lot of detail about this,
link |
the best way to ensure a healthy gut microbiome
link |
that I am aware of is not necessarily
link |
to take supplemental prebiotics or probiotics.
link |
There are actually some reasons
link |
why you might not want to do that,
link |
but rather to ingest two to four servings
link |
of fermented foods that are low in sugar each day.
link |
There is a recent study published in Cell
link |
showing that the ingestion of fermented foods,
link |
two to four servings each day,
link |
can enhance the quality of the mucosal lining of the gut
link |
that allows certain gut microbiota to flourish
link |
and the gut microbiota that are not good for us
link |
because that's the environment that they settle down into.
link |
This is work that was carried out
link |
by my colleagues Justin Sonnenberg,
link |
which is in the laboratory upstairs from me,
link |
as well as Chris Gardner and others at Stanford.
link |
They're certainly not the only researchers exploring this,
link |
but it does appear that two to four servings
link |
of fermented foods each day,
link |
so these would be things like natto, sauerkraut,
link |
low sugar fermented foods is great for the gut microbiome,
link |
and separate studies, not their study,
link |
but separate studies have shown
link |
that the correct gut microbiome conditions
link |
allow these neurons that signal to the brain
link |
to signal at the right times and in the right ways
link |
to promote healthy food seeking.
link |
Many people opt to supplement with capsule form probiotics.
link |
There are some data that suggest
link |
that maybe those don't contain the correct prebiotics
link |
and probiotics for setting
link |
the correct gut microbiota conditions.
link |
That's a little bit of a controversial issue.
link |
Nonetheless, getting probiotics from fermented foods
link |
is probably the simplest and most straightforward way.
link |
It's also the way that we evolved to do that over many,
link |
at least hundreds and probably thousands
link |
or even tens or hundreds of thousands of years
link |
people have been ingesting fermented foods,
link |
not just for their taste,
link |
but for their health benefits as well.
link |
So now I've mentioned two of the three mechanisms
link |
by which we prefer certain foods.
link |
One is from the actual taste that we're familiar with,
link |
the taste on our tongue and in our mouth
link |
and the sensations that make us go mm, or ugh,
link |
or eh, the yum, yuck, meh responses
link |
as I referred to them earlier.
link |
And then there's this subconscious signaling
link |
coming from the gut that's really based
link |
on the nutrient content of the foods.
link |
There's a third pathway, which is the learned association
link |
of a particular taste with the particular quality
link |
or value that a food has.
link |
And this is where things get really interesting
link |
and where there's actually a leverage point
link |
for you to rewire what it is that you find tasty
link |
and that you want to seek more of.
link |
The work I'd like to talk about next
link |
has been carried out in mouse models
link |
and has been carried out in parallel experiments in humans.
link |
This is largely, not exclusively,
link |
but largely the work of Ivan de Araujo and Dana Small.
link |
Ivan de Araujo is at Mount Sinai School of Medicine,
link |
and Dana Small is at Yale.
link |
And they and others in their field
link |
have done incredible experiments
link |
exploring how taste and food value,
link |
the nutritional value of food,
link |
and the impact of that food on metabolism in the brain
link |
drives our food choices
link |
and allows us to change our food choices for the better.
link |
Their groups have done some really amazing studies
link |
involving ingestion of a particular substance
link |
that either contains sugar
link |
and thereby can elevate glucose, blood sugar, or not,
link |
and varying, meaning changing the taste
link |
associated with that ingestion of sugar.
link |
So let me just give you a simple example
link |
where they have subjects,
link |
these could be mice or these could be humans,
link |
because they've done both sets of studies,
link |
drink sweet water as an alternative or a choice
link |
to non-sweetened water or bitter water or some other flavor.
link |
What they find is that mice and humans
link |
will prefer to consume the sweet beverage.
link |
Now it's not always sweet water.
link |
Mice like sweet water, but humans will prefer,
link |
for instance, a milkshake, a fatty sweet drink.
link |
They'll consume more of that.
link |
And not surprisingly, dopamine levels in the brain
link |
increase in response to that.
link |
So the taste and the nutrient content
link |
of what it is that they're ingesting are aligned.
link |
They've also done experiments where they have no taste,
link |
but subjects are being infused with sugar
link |
directly into the gut.
link |
And not surprisingly, based on everything I've told you
link |
up until now, subjects will pursue more of that thing
link |
relative to some other taste,
link |
either neutral or negative taste,
link |
because that sugar in the gut is triggering the activation
link |
of the neurons I mentioned earlier,
link |
which is signaling to the brain to pursue more of that thing.
link |
So this tells us something important.
link |
It tells us that we are driven,
link |
meaning we have mechanisms in our brain
link |
that make us motivated to pursue more
link |
of what brings both a taste of sweetness,
link |
but also that brings actual changes
link |
in blood glucose levels up, okay?
link |
So we are motivated to eat sweet things,
link |
not just because they taste good,
link |
but because they change our blood sugar level.
link |
They increase our blood sugar level.
link |
This is important because it needn't be the case.
link |
It could have been that we were just wired
link |
to pursue things that taste good.
link |
But what this tells us is that we are actually wired
link |
to pursue things that increase our blood glucose,
link |
so much so that when the small lab,
link |
it's not a small lab, it's actually a big lab,
link |
but when Dana Small's lab and or Ivan de Araujo's lab
link |
have done experiments where they use a compound
link |
called 2-deoxyglucose.
link |
This is a compound that can prevent glucose
link |
from being metabolized by neurons.
link |
So blood glucose is going up, but neurons can't use it.
link |
What they find is that the reinforcing
link |
or the rewarding properties of a food or taste
link |
Put simply, it is not sufficient
link |
for a food to taste good consciously.
link |
It is not sufficient for a food to increase blood sugar.
link |
You need blood sugar to go up and that blood sugar,
link |
glucose, has to be utilized by the neurons,
link |
even if it's not associated with a good taste
link |
and to make it even simpler, if this isn't sinking in,
link |
this should make it very clear.
link |
What your brain, meaning what you are seeking when you eat
link |
is not taste, is not dopamine,
link |
is not even a rise in blood glucose.
link |
What you're seeking, even though you don't realize it
link |
because it's subconscious, is you are seeking things
link |
that allow your neurons to be metabolically active.
link |
And this is fundamentally important for understanding
link |
why you eat particular foods
link |
and how you can change your relationship to those foods.
link |
Now, earlier, I referred to circuits that are wired
link |
for a particular outcome.
link |
And in biology and in particular neuroscience,
link |
we refer to things that are either hardwired,
link |
meaning immutable and unchangeable, or softwired.
link |
A good example of soft wiring would be the areas
link |
of your brain that are responsible for speech and language
link |
are always more or less in the same place in your brain
link |
and everyone else's brain.
link |
However, they are not hardwired to speak French
link |
or to speak English or to speak Chinese or to speak German,
link |
because depending on where you were born
link |
and the parents that you're born to,
link |
you need to be able to speak one
link |
or maybe even more languages.
link |
The taste system and this general system
link |
of seeking particular foods similarly is hardwired
link |
to obtain certain types of nutrients.
link |
It tends to like sweet things.
link |
Most children naturally like sweet things,
link |
some more than others,
link |
but naturally most people from childhood onward
link |
don't particularly crave very bitter substances,
link |
maybe mildly bitter, but not very bitter.
link |
So there's some hard wiring of preference,
link |
but there's also some soft wiring in the system
link |
that allows it to change.
link |
The groups I mentioned earlier
link |
have done some really beautiful experiments
link |
looking at how artificial sweeteners interact
link |
with the actual sweet sensing system.
link |
And this gets right down to a number of issues.
link |
First of all, it gets to the issue
link |
of how we can rewire our taste system
link |
in ways that serve us for better or for worse.
link |
Second of all, it gets right down to the issue
link |
of whether or not artificial sweeteners
link |
are good for us or bad for us.
link |
And indeed, as of just this last year,
link |
we now have an answer to that question.
link |
And turns out it depends.
link |
And I will tell you in a few minutes
link |
when it is okay to ingest artificial sweeteners
link |
and when it is very detrimental
link |
to ingest artificial sweeteners of any kind.
link |
Regardless, I'm not going to name off brand names,
link |
but there are different forms
link |
of these artificial sweeteners nowadays.
link |
And there are various forms
link |
of non-caloric plant-based sweeteners
link |
for which the same information
link |
that I'm about to tell you applies.
link |
Okay, so the experiments that were done
link |
beautifully illustrate that you seek out particular foods
link |
because of the way they taste,
link |
because of their impact on blood glucose levels,
link |
but also on their impact on the dopamine system,
link |
even if your blood glucose levels don't change.
link |
So here's the experiment.
link |
One group of subjects is given a sweet taste
link |
of a substance that also raises blood glucose levels,
link |
blood sugar, and dopamine goes up, not surprisingly.
link |
Second condition, separate subjects,
link |
consume an artificial sweetener or a non-caloric sweetener.
link |
It is not preferred much over other substances,
link |
but it is sweet, so it's preferred somewhat,
link |
and it does not cause an increase in blood glucose levels.
link |
And not surprisingly, dopamine levels don't go up.
link |
So initially, we don't tend to like
link |
artificial sweeteners that much.
link |
That's the simple way of putting it.
link |
However, if subjects continue
link |
to ingest artificial sweeteners,
link |
even though there's no increase in blood glucose level,
link |
and therefore no increase in brain metabolism,
link |
dopamine levels eventually start to rise.
link |
And when those dopamine levels eventually start to rise,
link |
you've essentially conditioned or reinforced
link |
that artificial or non-caloric sweetener,
link |
and then subjects start to consume more of it,
link |
and they actually get a dopamine increase from it.
link |
So that's interesting.
link |
It says that consuming more of these artificial sweeteners
link |
or consuming them for a longer period of time
link |
can start to tap into the dopamine system
link |
and lead us to seek out or consume
link |
more of these artificial sweeteners.
link |
Many people are probably familiar with this
link |
because we tend to, or I should say,
link |
people report that when they ingest
link |
these artificial sweeteners,
link |
at first they don't taste very good,
link |
but then over time, they seem kind of tolerable,
link |
and then maybe even pleasurable,
link |
and then some people feel quote unquote addicted
link |
to various diet sodas and things of that sort.
link |
Now, there's another condition that's been explored,
link |
and that's the really interesting condition.
link |
And it's the condition where an artificial sweetener
link |
is paired with a substance that can increase blood sugar,
link |
but not because it tastes sugary
link |
like a normal sweet substance.
link |
So now there's an artificial sweetener
link |
that's coupled with an actual increase in blood glucose.
link |
The natural world scenario where this would happen
link |
would be drinking a diet soda, which contains no calories
link |
and therefore would not increase blood glucose,
link |
but is sweet with a food that increases blood glucose.
link |
And when that happens, what you're essentially doing
link |
is tapping into the dopamine system,
link |
this non-chloric sweet taste is paired with it,
link |
and there's an increase in neuron metabolism.
link |
So you have all of the components for reinforcement.
link |
And as a consequence, you get in a sort of Pavlovian
link |
conditioning way, a situation where later,
link |
when you ingest that artificial sweetener,
link |
you actually get not only the increase in dopamine,
link |
but you get alterations in blood sugar management.
link |
Now, blood sugar cannot go up if you don't ingest something
link |
that makes blood sugar go up.
link |
So it's not as if you ingest artificial sweetener
link |
with some food that contains calories or sugar,
link |
and then later you remove the food
link |
and you just drink the soda and your blood glucose goes up.
link |
Rather, it's a much worse situation.
link |
If you, I'll make this in the natural world context,
link |
if you ingest an artificial sweetener,
link |
say drink diet soda while consuming foods
link |
that increase blood glucose, then later,
link |
even if you just drink the diet soda,
link |
it's been shown that you secrete much more insulin,
link |
the hormone that regulates blood glucose
link |
in response to that diet soda.
link |
Studies have been done in both adult humans
link |
and in human children.
link |
In general, when we say children, we mean human children,
link |
but just to be very clear what we're talking about,
link |
exploring consuming diet soda with or without food,
link |
then later consuming just the diet soda.
link |
And what they found was having previously consumed
link |
diet soda with food and then later only consuming
link |
the diet soda, of course, there isn't an increase
link |
in blood glucose because they're not bringing in
link |
any calories when they just drink the diet soda,
link |
but there is a significant increase in insulin release.
link |
And that is serious in a terrible way
link |
because increased release of insulin
link |
and so-called insulin sensitivity is the basis
link |
for type two diabetes.
link |
So much so that in the study with the children,
link |
consuming non-caloric beverages in this way,
link |
first with food and then on their own,
link |
led to increases in insulin that made them pre-diabetic
link |
and they actually had to halt the study.
link |
So I want to zoom out from this and just really illustrate
link |
the major findings and then talk about how this can be
link |
applied in the positive sense.
link |
I also want to mention what this means in terms of your
link |
consumption of artificial sweeteners of any kind.
link |
So first of all, the direct takeaway
link |
about artificial sweeteners.
link |
Artificial sweeteners are not bad for you.
link |
I'm not going to say that.
link |
What I am going to say is that whether or not you ingest
link |
them alone or you ingest them in combination with foods
link |
or as part of foods that raise blood glucose
link |
is vitally important for your insulin management.
link |
And the simple extract or tool from this is if you're going
link |
to consume artificial sweeteners,
link |
it's very likely best to consume those away from any food
link |
that raises blood glucose levels.
link |
So if you're going to enjoy diet soda, be my guest,
link |
but do it while not while consuming food,
link |
in particular foods that raise blood glucose,
link |
because what these studies show,
link |
and I will provide references for these,
link |
is that they can vastly disrupt blood sugar management
link |
by way of the insulin glucose system, okay?
link |
And actually I'll just give you the reference now.
link |
This is a paper from Dana Small's lab.
link |
The first author is Dallenberg, D-A-L-E-N-B-E-R-G.
link |
And the title of the paper is short-term consumption
link |
of sucralose with, but not without carbohydrate impairs
link |
neural and metabolic sensitivity to sugar in humans.
link |
This is a paper published in Cell Metabolism
link |
I think it's a very important paper and similar findings
link |
have been addressed in mice and in other studies.
link |
And now because of this paper,
link |
there's now a bunch of other groups working on this issue.
link |
There's some evidence previously published in Nature,
link |
excellent top tier journal among the Super Bowl
link |
of top three journals being Nature Science and Cell.
link |
Paper published in Nature a few years back
link |
showing that particular artificial sweeteners
link |
can disrupt the gut microbiome
link |
and have deleterious health effects.
link |
That result, I think, stands,
link |
although there are some results that may not agree
link |
with that depending on whether or not
link |
the artificial sweetener is saccharin or sucralose
link |
or aspartame or stevia, that's the gut microbiome.
link |
But what we are talking about here is independent
link |
of the form of artificial or non-chloric sweetener
link |
because it has everything to do with whether or not
link |
there is a match or a mismatch between the perceived taste
link |
and the effect of the thing that you are consuming
link |
on blood sugar and metabolism.
link |
So the first takeaway from this is
link |
if you're going to consume artificial sweeteners,
link |
it's really important that you do that,
link |
not in conjunction with foods that increase blood glucose.
link |
Second of all, it points to the fact
link |
that the foods that we prefer
link |
and the activation of the dopamine system,
link |
both through the gut and at the level of conscious taste,
link |
in other words, what we like is very plastic,
link |
it's mutable, and we can change it.
link |
How can we change it?
link |
Well, earlier I mentioned a structure in the brain
link |
called the insula, this incredible structure
link |
that's involved in interoception
link |
and interoception of all kinds.
link |
In fact, just as an aside, a year or so ago,
link |
my lab published a paper showing that
link |
activity within certain compartments of the insula of humans
link |
is responding to a heightened state of anxiety in the body.
link |
It can respond to changes in our respiration,
link |
changes in our heart rate.
link |
So this is, again, it's a readout of our internal state,
link |
not just of taste, but of many, many different aspects
link |
of the mechanics and chemistry of our internal milieu
link |
All of the work that I was describing previously
link |
has also been addressed at the neural level.
link |
And using a broad brush to explain these results,
link |
what we can say is when there is dopamine increase,
link |
one sees activation of the so-called nucleus accumbens,
link |
which is part of the so-called mesolimbic reward pathway.
link |
If you'd like to learn more about the mesolimbic reward
link |
pathway and dopamine in general and humans
link |
and in animal studies and all the various incredible
link |
and challenging things that dopamine can do for us,
link |
there's a episode all about dopamine that you can look up.
link |
It's easy to find at hubermanlab.com.
link |
The increases in dopamine associated with sweet taste
link |
and or blood glucose elevating foods and drinks
link |
cause activation of the nucleus accumbens.
link |
That's not surprising.
link |
Also in the circuit is activation
link |
of the so-called arcuate nuclei within the hypothalamus.
link |
These are areas of the hypothalamus that respond
link |
to hormones from the body and respond to hormones
link |
and neuropeptides in the brain,
link |
as well as neural signals in the brain
link |
to drive us to eat more or to stop eating.
link |
So it's hypothalamus, nucleus accumbens.
link |
These are sort of the hypothalamus and the arcuate
link |
being the motivating to eat or motivating to stop eating.
link |
Both sets of neurons are contained there.
link |
There are other areas like the lateral hypothalamus as well,
link |
but hypothalamus is sort of the accelerator
link |
and the brake on eating.
link |
And then the nucleus accumbens and dopamine release
link |
can be thought of as kind of a nitro boost, if you will,
link |
like the kids say, do the kids say that anymore?
link |
Anyway, a nitro boost to increase what we call the gain
link |
or the volume of how much you want more of something, okay?
link |
When dopamine is present, it's this kind of generic signal
link |
to go seek out more of whatever caused that release.
link |
And then there's the insula,
link |
this very thoughtful, rational, not really,
link |
it's not thinking, it's a brain area, you're thinking,
link |
but it's part of the areas of your brain
link |
that are interpreting what's going on in your body,
link |
whether or not you feel good or not good,
link |
whether or not you feel anxious, excited, or fearful.
link |
It's integrating all that information
link |
and fed into this entire circuit as well
link |
are the inputs from your prefrontal cortex,
link |
which is your thinking, rational, neuronal structure,
link |
if you will, informing you, for instance,
link |
ah, well, I don't really like salmon very much,
link |
or I'm not so crazy about kale, but it has omega-3s,
link |
or it's rich in these polyphenols that are good for me.
link |
And if one decides that they are going to eat these things,
link |
not just because they are good for them,
link |
but believe it or not, if one takes the perception
link |
or adopts the perception that they are both good for you
link |
and that in being good for you,
link |
they are good for your brain metabolism,
link |
and that you desire to be healthy, as crazy as it sounds,
link |
those subjective signals of what you tell yourself
link |
about the foods that you're eating
link |
can actually impact how those foods will taste,
link |
maybe not immediately, but eventually,
link |
and can impact the way in which
link |
your body utilizes those foods.
link |
Now, that might seem like a absolute pipe dream.
link |
If I just imagine that I like mackerel,
link |
mackerel will start to taste good.
link |
I'm not saying that.
link |
I didn't say that you could override yuck signals
link |
with this mechanism.
link |
I didn't say that you could take a food
link |
that would be absolutely noxious to you
link |
or make you want to vomit and override that.
link |
However, foods that are somewhat neutral to you
link |
can take on a different value
link |
based on the activation of the dopamine system.
link |
And now, knowing what you know,
link |
there are a couple of ways that you could imagine doing that.
link |
First of all, you could, in this so-called gedanken
link |
or thought experiment, you could, for instance,
link |
swap out sucralose because sucralose is just a taste, right?
link |
It's an artificial sweet taste.
link |
You could swap that out and insert kale,
link |
but eat the kale with something that raises blood glucose
link |
to some degree or another.
link |
Now, I'm not encouraging anyone to run out there
link |
and spike their blood glucose like crazy.
link |
And in fact, blood glucose isn't really the goal.
link |
If you recall, the goal is to get neurons
link |
to be metabolically active with that blood glucose, okay?
link |
That's what's actually rewarded at a subconscious level,
link |
meaning at a deep subconscious level.
link |
But consuming these foods with other foods
link |
that increase blood glucose and thereby brain metabolism,
link |
or I suppose if you're ketogenic, you're in a ketosis,
link |
I don't know what the range of foods
link |
that are allowed on ketosis are,
link |
so I don't want to misspeak here and say cracker,
link |
which would probably be a sin in the context of ketosis,
link |
and no knock against ketosis.
link |
I'm offering this in part
link |
because I think that there are a number of people
link |
that have and can positively benefit from a ketogenic diet.
link |
if there's a food that you want to consume more of,
link |
but that you find somewhat meh or mildly yuck even,
link |
pairing it with ketones,
link |
if indeed you are using ketones for your brain metabolism,
link |
because that's what happens on the ketogenic diet,
link |
over time, that food will be reinforced
link |
by the dopamine pathway.
link |
We know this from these studies where sucralose
link |
was the substance paired with the glucose elevating,
link |
metabolically elevating food substance or liquid substance.
link |
So how does one go about doing this?
link |
Well, first of all,
link |
I want to emphasize that this experiment
link |
actually has been done in a slightly different context.
link |
Studies by my colleague Alia Crum
link |
in the psychology department at Stanford
link |
have explored the bodily response
link |
in terms of insulin release
link |
and the release of other food and eating related hormones,
link |
as well as overall feelings of satisfaction, et cetera,
link |
in groups of people that drink a milkshake
link |
and are either told that it's a low calorie shake
link |
that contains various nutrients that are good for them,
link |
or a higher calorie shake
link |
that has a lot of nutrients, et cetera,
link |
and what they found was that the different groups,
link |
I'm being very general with my description of these studies,
link |
but what they found is that the physiological response,
link |
the insulin response, the blood glucose response,
link |
and the subjective measures
link |
of whether or not people enjoyed something or not
link |
were heavily influenced by what they were told
link |
were in these milkshakes.
link |
So blood glucose would go up, insulin would go up
link |
when people were told it was a high calorie shake
link |
with lots of nutrients,
link |
less so when people ingested a shake
link |
that they were told had less nutrients and so forth,
link |
when in reality, it was the identical shake.
link |
This is incredible.
link |
This is a belief effect.
link |
This is not placebo, right?
link |
A placebo effect is different.
link |
Placebo effect is in comparison.
link |
It's where the control condition
link |
actually influences outcomes to a same,
link |
or to some degree, just like the experimental condition.
link |
This is not a placebo effect.
link |
This is a belief effect
link |
where the belief and the subjective thoughts
link |
about what a given food will do
link |
has a direct impact on a physiological measure
link |
like blood sugar and blood glucose, okay?
link |
So let's zoom out from this for a second
link |
and think about how we can incorporate this
link |
into adopting consumption of healthy foods
link |
that serve our brain health in the immediate and long-term.
link |
And if you're wondering what those are,
link |
I listed them out at the beginning of the episode
link |
and their justification for being on that list.
link |
What this means is,
link |
obviously you want to consume foods that you like,
link |
but because brain health is very important
link |
and many of the foods that promote brain health
link |
perhaps are not the most palatable to you
link |
or desirable to you,
link |
the key would be to ingest the foods
link |
that you want to ingest more of
link |
simply because they're good for you
link |
and not because they taste good to you.
link |
Alongside foods that increase
link |
whatever fuel system you happen to be relying on,
link |
I think that's the most nutritionally
link |
politically correct way to say it.
link |
So if you're keto, that would mean ketones, okay?
link |
If you're not ketogenic,
link |
and I think most people probably are not in ketosis
link |
or trying to maintain ketosis,
link |
but for instance, people that are on a purely
link |
plant-based diet, that would be one set of foods.
link |
For people that are omnivores, a different set of foods,
link |
and for people that are carnivores,
link |
yet another set of foods.
link |
If you want to eat more of a particular food
link |
because it's good for you,
link |
pair it with something in the same meal.
link |
You don't have to hide it physically or in the flavor sense.
link |
You don't have to hide it within that other food,
link |
but pair it with that other food
link |
that provides you a shift in brain metabolism
link |
because that's really what your brain and you are seeking
link |
even though you don't realize it.
link |
How long will this take?
link |
Well, according to the data in humans on sucralose
link |
and the conditioning for sucralose to have these effects,
link |
which in many cases were detrimental, right?
link |
Because they were increasing insulin.
link |
you're trying to hijack this conditioning of food preference
link |
for healthy purposes, not with sucralose,
link |
but by ingesting things that are good for you,
link |
then the data really points to the fact
link |
that even within a short period of time of about seven days,
link |
but certainly within 14 days,
link |
that food will take on a subjective experience
link |
of tasting at least better to you, if not good to you.
link |
Now, I believe this has important implications
link |
for much of the controversy and food wars
link |
that we see out there.
link |
Food wars being, of course,
link |
these groups that ardently subscribe to the idea
link |
that their diet and the things that they are eating
link |
are the foods that are good for us
link |
and that are the most pleasureful
link |
and the things that everyone should be eating.
link |
We see this with every community within the nutrition realm.
link |
Now, of course, there are studies that point to the fact
link |
that certain foods and food components are healthier
link |
probably for us and for the planet,
link |
but you really see it on both ends of the spectrum.
link |
You've got people who are on a pure carnivore diet
link |
who are arguing with a lot of biomedical evidence
link |
that that's what's best for us and beneficial.
link |
And then you've got people
link |
that are arguing the same general sets of arguments,
link |
but for a purely plant-based diet.
link |
And then I think most people fall into the omnivore category.
link |
What's very clear, however,
link |
is that what we consume on a regular basis
link |
and what leads to increases in brain metabolism
link |
leads to increases in dopamine
link |
and thereby our motivation to eat them.
link |
So what this really says is that what we tend to do regularly
link |
becomes reinforcing in and of itself.
link |
And I think in large part can explain the fact that,
link |
yes, indeed, for certain people,
link |
a given diet not only feels good,
link |
but they heavily subscribe to the nutrient
link |
and kind of health beneficial effects of that diet.
link |
And they often will provide evidence for that,
link |
whether or not you ask them for it or not.
link |
But that's true of every subcategory
link |
within the nutrition realm.
link |
Again, this is not to take away
link |
from some of the beautiful data emphasizing
link |
that certain foods and micronutrients, et cetera,
link |
are better for us or worse for us and for the planet.
link |
That's not a debate I want to get into right now.
link |
What this emphasizes is that foods impact our brain
link |
but they also impact how our brain functions
link |
and responds to food.
link |
And that is largely a learned response.
link |
We can't completely override, for instance,
link |
that certain foods evoke a strong yuck component.
link |
Certain foods are truly putrid to us.
link |
I should just say certain things are putrid to us
link |
and we should not consume them, right?
link |
And that's at the far end of the spectrum,
link |
it's hardwired for us to avoid those
link |
because they can be dangerous for us.
link |
They can make us very, very sick.
link |
But it's also true that if we continue to eat foods
link |
that are progressively sweeter and sweeter
link |
and highly palatable, it shifts our dopamine system
link |
because it activates our dopamine system
link |
to make us believe that those foods are the only foods
link |
that can trigger this reward system
link |
and make us feel good and taste,
link |
and that they taste good.
link |
But after consuming foods that perhaps are less sweet
link |
or even less savory that are not what we would call highly,
link |
or I would say nowadays it's super palatable foods,
link |
we can adjust our sense literally of what we perceive
link |
as an attractive and rewarding food.
link |
And indeed the dopamine system
link |
will reward those foods accordingly.
link |
I can't emphasize enough how much this learning
link |
of associated food reward is important
link |
for not just understanding why we like the foods
link |
that we eat and how to eat more of foods
link |
that are healthy for us and enjoy them.
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But it also speaks to the fact that our brain as a whole
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is a perceptual device trying to make guesses
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or estimations about what certain foods
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are going to do for us.
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So put simply, we don't just like sweet foods
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because they taste good.
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We like them because they predict
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a certain kind of metabolic response.
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This is important also because Dana Small
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and Ivan de Araujo and others have been exploring
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whether or not people, for instance,
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that have type 2 diabetes or that suffer
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from any number of different metabolic disorders,
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whether or not somehow these food reward systems
link |
are permanently disrupted.
link |
And through a beautiful set of experiments
link |
that have been done mainly by Dana Small's group at Yale,
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but also by the de Araujo group and others,
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exploring how the reward pathways are altered
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in various metabolic disorders, et cetera,
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people suffering from type 2 diabetes.
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We don't have time to go into all those data now,
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but the takeaway is that food preference
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and the ability to reshape these circuits
link |
is not disrupted in these people to the point
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where it can't be rewired.
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And that's very encouraging because what it means is that
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for people that are suffering from these syndromes
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through some simple alterations in dietary choice,
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provided those are carried out over time
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and in the correct way by pairing with the foods
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that will appropriately shift metabolism of the brain,
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one can actually rewire what they consider
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not just palatable, but attractive as foods.
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If you want to learn more about food reward
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and food reinforcement,
link |
because it turns out those are slightly different things,
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there's a wonderful review written by Ivan de Araujo.
link |
They have a middle author, Mark Schachter and Dana Small.
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It's called Rethinking Food Reward,
link |
and it was published in the Annual Reviews of Psychology.
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You can find it very easily online.
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It was published in 2019.
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And it's a beautiful deep dive,
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although quite accessible to most people,
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about how different foods and the way that we perceive them
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impacts our brain and body
link |
and why we like the things we like
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and how to reshape what we like.
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So once again, we've done a fairly extensive deep dive
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into food and your brain,
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focusing first on how particular foods
link |
and compounds within foods that are available
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also through supplementation
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can impact immediate and long-term brain health.
link |
Came up with a relatively short list
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of what I would call super foods,
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only because there are ample data to support their role
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in enhancing short and long-term cognition
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and neuronal health and so on.
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And we also talked about food preference
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and why particular tastes
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and particular events within the gut
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and particular events within the brain
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combine to lead us to pursue particular foods
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and to avoid other foods
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and how you can leverage those pathways
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in order to pursue more of the foods
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that are going to be good for you
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and good not just for your brain,
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but for your overall body health
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and to enjoy them along the way.
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If you're learning from and or enjoying this podcast,
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please subscribe to our YouTube channel.
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That's a terrific zero cost way to support us.
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In addition, please leave us suggestions for future topics
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and guests you would like us to host
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in the comment section on YouTube.
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As well, please subscribe to the Huberman Lab podcast
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on Apple and or Spotify.
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And on Apple, you can leave us up to a five-star review.
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If you're not already following us on Instagram,
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we are Huberman Lab at Instagram.
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And there I do neuroscience tutorials
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that sometimes have overlap with the podcast,
link |
but often are original content altogether.
link |
We are also Huberman Lab on Twitter.
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Another terrific way to support us
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is by checking out our sponsors
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that we mentioned at the beginning of the episode.
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We also have a Patreon.
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It's patreon.com slash Andrew Huberman.
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And there you can support the podcast
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at any level that you like.
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During today's podcast and on many other previous episodes,
link |
we talked about various supplements.
link |
One of the major issues with supplements
link |
is that supplement companies don't always have
link |
the highest quality standards
link |
and or the amounts of the supplements
link |
that they list on the bottle
link |
aren't what actually are contained
link |
in the capsules and pills and powders of those supplements.
link |
For that reason, we partner with Thorne, T-H-O-R-N-E,
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because Thorne has the highest levels of stringency
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with respect to the quality of the supplements they use
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and the quantity of the supplements they use.
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They've partnered with all the major sports teams
link |
and with the Mayo Clinic,
link |
and we have tremendous confidence
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in the quality of their supplements.
link |
If you'd like to see the supplements that I take,
link |
you can go to thorne, T-H-O-R-N-E,
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.com slash the letter U slash Huberman.
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There, you can get 20% off any of those supplements,
link |
and if you navigate into the main site
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through that portal of thorne.com slash U slash Huberman,
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you can also get 20% off any of the supplements
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that Thorne makes.
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And last but not least,
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thank you for your interest in science.