Essentials: Food & Supplements for Brain Health & Cognitive Performance

Andrew Huberman: Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science-based tools for mental health, physical health, and performance. I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine.

Today, we are talking all about food and the brain. We are going to talk about foods that are good for your brain in terms of focus, in terms of brain health generally, and the longevity of your brain, your ability to maintain cognition and clear thinking over time. We are also going to talk about why and how you prefer certain foods to others.

And I'm going to talk about the three major signals that combine to drive your food choices. One of those signals comes from your gut and is completely subconscious. These are neurons in your gut that are sending signals to your brain that you are unaware of about the nutrient contents of the foods that you're eating.

The second signal is how metabolically accessible a given food is, meaning how readily that food can be converted into energy that your brain, not your body, but that your brain can use. And the third signal is perhaps the most interesting one. It's the signal of belief. It's the signal of what you perceive and believe the food that you're eating to contain and what you think it can do for you healthwise and energy-wise.

What are the things that directly impact brain health and what are the foods that we can eat that will support brain health? Generally, when we think about neuron function and brain function, we default to a discussion about fuel, the fact that neurons use glucose, which is blood sugar, in order... and that they require a lot of it.

But before we can even consider the fuels that neurons use in order to function, we have to talk about the elements that actually allow those neurons to be there and to stay healthy, what actually makes up those neurons. And that brings us to what I would argue is the most important food element for brain function, and that is fat.

And that might come as a surprise, but unless one considers the water content of the brain, which is very high, a lot of our brain and a lot of the integrity of the nerve cells, the so-called neurons in our brain, and the other types of cells comes from fat. And that's because nerve cells and other cells in the brain have a, uh, external layer. It's, uh, what's sometimes called a double-layered membrane. It's essentially two thin layers that serve as a boundary between those cells, and that boundary is very important because how things pass across that boundary actually regulates the electrical activity of neurons, which is the way that neurons fire and communicate and keep you thinking and acting and doing all the good things that those neurons allow us to do.

And those membranes are made up of fats, but they're not made up of the fats that are around our belly, around the other organs of our body. They're not made up of storage fat. They are made up of structural fat. And maintaining the so-called integrity of that structural fat, meaning the health of those neurons, is going to come in large part from the foods that we eat.

So, what type of fat is it and what should we eat in order to support that fat and those neurons? And the answer is the so-called essential fatty acids and phospholipids. Now, those are more or less the same thing, but I just want to make a very large literature very crystal clear. Essential fatty acids can include the so-called EPA variety or DHA variety. You hear about Omega-3s and Omega-6s. Most people are getting enough Omega-6s from their diet. However, most people are not getting enough Omega-3s in their diet to support healthy brain function in the short and long term.

What are foods that are high in Omega-3s that we should all probably be consuming at least on a daily basis? The number one is fish. Now, I don't know about you, but I'm not eating a lot of fish. I will from time to time, but that's one reason why one might want to supplement with EPAs from another source. But also, EPAs are found in chia seeds, in walnuts, in soybeans, and other plant-based foods. You can look these up online and you'll immediately see that there are a lot of sources of EPAs.

And many of the foods that I listed off might be appetizing to you, some of them might be unappetizing to you, or some of them you might be sort of neutral about. But it's very clear that eating foods that are rich in Omega-3s and or supplementing with Omega-3s to get above that 1.5 grams, and ideally up to two or even three grams per day of EPA can be very beneficial for cognitive function in the short and long term.

The other compound that has been shown to be directly supportive of neuronal function is phosphatidylserine, which is abundant in meats and in fish. So, for those of you that do consume meat and fish, provided you're getting enough fish you're probably getting enough phosphatidylserine. For those of you that are interested in supplementing with phosphatidylserine, it's a relatively inexpensive supplement that, again, is lipid-like. So, it's mimicking some of the same things that you would get from food, but in higher concentration.

Now, after EPA, fatty acids and phosphatidylserine, I would say third on the list of things that come from food that can readily support brain function would be choline. And that's because of the relationship to choline in the biosynthesis pathway for acetylcholine. Acetylcholine is a neuromodulator, not a neurotransmitter, but a neuromodulator in the brain. So, it's kind of a electrical highlighter pen, if you will, by analogy. That is the basis of much of what we call focus or, or our ability to concentrate on a particular batch of information that's coming in through our eyes, our ears, our nose, or even things that we're just thinking in our head.

And not surprisingly then, many of the treatments for Alzheimer's disease, which is inabil- inability or challenges with remembering things and focusing, are drugs that impact the acetylcholine pathway and are aimed at enhancing the amount of acetylcholine that's available to neurons. And the primary source for dietary choline would be eggs, and in particular egg yolks.

Eggs are an incredibly rich source of nutrients for the brain, and that's because the egg actually, if you think about it, contains all the nutrients that are required in order for an organism to grow. So if you're somebody who doesn't eat eggs or doesn't want to eat eggs, things like potatoes, nuts and seeds and grains and fruit, they don't have as much choline as eggs, but they do contain cholines. In general, most people should probably strive to get somewhere between 500 milligrams and a gram of choline per day, so 1,000 milligrams.

Next on my list of compounds that have been shown in peer-reviewed research to improve neuronal and brain function is creatine. Creatine can be derived from meat sources. It can also be supplemented. Creatine can actually be used as a fuel source in the brain, and it, there's some evidence that it can enhance the function of certain, uh, frontal cortical circuits that feed down onto, or rather connect to areas of the brain that are involved in mood regulation and motivation.

What is the threshold level of creatine to supplement in order to get the cognitive benefit? Appears to be at least five grams per day. Now, the most typical form of creatine is so-called creatine monohydrate. Think it's interesting that creatine supplementation of five grams per day, that's creatine monohydrate, has been shown to improve cognition in people that aren't getting creatine from animal sources.

So I personally take creatine, five grams per day, and have for a very long time. I can't say that I've, uh, noticed a tremendous benefit because I've actually never really come off it. Uh, and so I've never done the control experiment. I take it more as kind of a baseline insurance policy for me. But, uh, what I can say is that I generally consume these things like EPAs, creatine, alpha-GPC to set a general context of support for my neurons, uh, for my brain, and of course, I do also pay attention to the foods that contain these various compounds.

So I don't actively eat additional meat just to obtain creatine. Um, I eat a fairly limited amount of meat. I don't restrict it, but I, and I do eat meat. But, um, I don't actively seek out creatine in my diet. Rather, I use supplementation in order to hit that five grams per day threshold.

Next on the list of foods that are beneficial for brain health is one that you've probably seen pictures of online because there seems to be a practice of putting pictures of blueberries and other dark berries next to any title that says, "Foods that benefit your brain." Uh, there are a lot of foods out there that have been purported to improve brain function. The interesting thing about blueberries and other berries, blackberries, dark currants, any of these thin-skinned berries that are purplish in color, is that they contain what are called anthocyanins.

Anthocyanins actually have some really nice data to support the fact that they improve brain function. Now, whether or not it is direct effects on neurons or whether or not it is by lowering inflammation, um, or some other modulatory effect isn't quite clear, but I think by now there's enough data to support the fact that eating a cup or two of blueberries pretty often, every day, or maybe you have blackberries or maybe it's black currants, that these anthocyanins are, are good for us, that they are enhancing our overall well-being at a number of different levels.

So we've got EPA fatty acids, we've got phosphatidylserine, we've got choline, we've got creatine, and we have the anthocyanins. And the last item that I'd like to place in this list of food-derived things that can enhance brain function is glutamine.

Glutamine is a very interesting amino acid. I've talked about glutamine on here before. There's some evidence, although somewhat scant, there's some evidence that glutamine can enhance immune system function, so people will supplement with glutamine or people can get glutamine from foods. Foods that contain a lot of glutamine are things like cottage cheese. There are also other sources of glutamine. Glutamine is rich in protein-rich foods, things like beef, chicken, fish, dairy products, eggs, but also for you non-um, animal food, uh, consuming people out there, um, vegetables including beans, cabbage once again, spinach, parsley, things of that sort. So those foods contain glutamine.

For people that supplement with glutamine, generally they will take anywhere from a gram, as much as 10 grams per day. Why would they want to do that? Well, there's also some evidence starting to emerge that glutamine can help offset sugar cravings. In brief, we all have neurons in our gut that sense the amino acid content, the fat content, and the sugar content of the foods that we eat, and signal in a subconscious way to our brain whether or not the foods that we're eat, we are eating contain certain levels of certain amino acids.

And so we actually have glutamine sensing neurons in our gut that actually have their little processes, their little, um, axons and dendrites as we call them in the mucosal lining of the gut. They're not just sensing glutamine, but when they do sense glutamine, they respond and they send signals to the brain that are signals of satiation, of satisfaction. And in doing so, can offset some of the sugar cravings that many people suffer from.

So, that more or less completes the list of things that, at least by my read of the literature, are things that are supported by at least three, and in some cases as many as hundreds of studies, in various populations, that have been, uh, explored in mouse studies often, but also in a number of human studies. I want to emphasize again that all of the things I listed out, whether or not it's EPAs, whether or not it's phosphatidylserine, whether or not it's choline, whether or not, uh, it's the various compounds that are in berries, et cetera, all of those can be extracted from food.

There is not any law that says that you have to get them from supplementation. Supplementation can help you get to the very high levels of those things if you want to work on the higher end, if that's right for you. Obviously check with your doctor before taking anything or removing anything from your diet or supplement regime. But in general, you can get these things from foods. It just so happens that for some of these, uh, compounds, the foods that they're contained in, like fish, are not foods that I, um, particularly enjoy, and so I rely on, excuse me, I rely on supplements in order to get sufficient levels for me. But again, you can get these levels from food.

And the reason I made this list, the reason that I emphasized these things in this particular order is that they support the structure of neurons, they support the structure of the other cells of the brain that make up our cognition and that are important for our focus and our ability to remember things and so forth. And they are less so in the category of so-called modulatory effects. They will also have modulatory effects on sleep, on inflammation, or reducing inflammation throughout the body, on cardiovascular function, all of which I believe are positive effects, at least what the literature tells us, is that none of these compounds are harming other systems of the body, provided they are taken at, uh, reasonable levels.

But everything in this list is directed towards answering the question, what can I eat, what can I ingest by way of food and/or food supplement that can support brain function in the short term and in the long term? So, I hope you find that list beneficial for you, if not for use, at least for consideration.

So now, having talked about some of the foods and micronutrients that are beneficial to our immediate and long-term brain health, I'd like to shift gears somewhat and talk about why it is that we like the foods that we like. We've all heard before that we are hardwired to pursue sugar and to like fatty foods, and that calorie rich foods are attractive to us for all sorts of reasons, you know, surviving famines and things of that sort. And while that is true, the actual mechanisms that underlie food seeking and food preference are far more interesting than that.

There are basically three channels in our body and nervous system by which we decide what foods to pursue, how much to eat, and whether or not we will find a particular food attractive, whether or not we will want to consume more of it, whether or not we want to avoid it, or whether or not it's just sort of so-so. What I refer to as the yum, yuck, or meh analysis. And indeed, that's what our nervous system is doing with respect to food. So, let's talk about what these three channels for food preference are.

The first one is an obvious one. It's taste on the mouth. It is the sensation that we have of the foods that we eat while we're chewing them, and those sensations, which are literally just somatosensory, touch sensations, you know, the palatability of food as it relates to the consistency of food. That's important. And as you've all heard before, we have sensors on our tongue and elsewhere in our mouth that detect the various chemicals contained within food and lead to the senses of taste, which we call bitter, sweet, umami, salty, and sour.

The umami receptor is a receptor that responds to the savory taste of things, so that's what you might find in a really wonderfully rich tomato sauce. For those of you that eat meat and like meat, um, a really well-cooked, not necessarily well done, but properly cooked, I should say, steak, if that's your thing. And umami is present in both plant and animal foods, and gives us that sensation of savoriness.

So, we have those five basic tastes. Those are chemical sensors on the tongue that what we call transduce those chemicals. Those chemicals literally, in food, bind to those receptors and it is transduced, meaning the binding of those chemicals to the receptors is converted into an electrical signal that travels in from the tongue along what's called the gustatory nerve, then synapses, meaning, meaning it makes connections in our brain stem, in the so-called nucleus of the solitary tract. There are other nuclei back there. Nuclei are just aggregates of neurons. And then it sends information up to the so-called insular cortex.

The insular cortex is a incredible structure that we all have that mainly is concerned with so-called interoception, or our perception of what's going on inside our body. So, it could be the amount of pressure in our gut because of how much food we've eaten, it could be the acidity of our gut, if we're having a little bit of indigestion, for instance. And not surprisingly, the taste system sends information up to the insular cortex to give us a sense, literally, of what we've ingested, whether or not what we're tasting tastes good or not.

What this means is that your perception of what you like is a central, meaning with- deep within the brain, phenomenon. It's not about how things taste on your mouth, but as we'll see in a few minutes, turns out that that is not a direct relationship that is hardwired. You can actually uncouple the preference for particular tastes with the reward systems in the brain. It's actually possible to rewire one's sense of taste and preference for particular foods. But the most important thing to understand is that, like with our hearing, like with vision, like with smell, taste is an internal representation that has particular goals for you. Your sense of what tastes good is related to particular things that are occurring in your brain and body, and that are likely to give your brain and body the things that it needs. It is not simply a matter of what you quote unquote like or what tastes good or what doesn't taste good.

Let me give you a relatively simple example of how your body and your brain are acting in a coordinated way to make you prefer certain foods, and indeed to pursue certain foods more. So, I just mentioned you have neurons on your tongue that respond to different tastes. But of course, your digestive tract isn't just your tongue, it's also your throat, goes all the way down to your stomach, and of course your intestines. There's a long tube of digestion. All along that tube, there are neurons.

Some of the neurons are responding to the mechanical size of whatever portion of the digestive tract it happens to be. So for instance, how distended or empty, or full rather, it doesn't have to be distended , how, uh, depends on how much you ate, but how full or empty your gut happens to be. Whether or not something you just ate is temperature hot, you know, is hot, uh, in the sense of hot to the touch, or whether or not it's spicy hot, whether or not it's soothing, whether or not it's kind of hard to swallow, this kind of thing. So you have neurons all along your gut that are responding to the mechanics related to food and digestion, and that are related to the chemistry of food and digestion.

There's a population of neurons, nerve cells in your gut that are exquisitely tuned to the chemistry of whatever it is in your gut. And these are neurons called neuropod cells. They respond to amino acids, sugars, and fatty acids. So as your food is digested, as food lands within your gut, neurons there are sensing what types of foods are available and what types of things are making their way through the gut environment. And these particular neurons send electrical signals up into the brain through a little passage that we call the nodose ganglion. The nodose ganglia is a, a cluster of neurons that then go furth- send up their own process into the brain and trigger the release of dopamine, which is a molecule that inspires motivation, reward, and more seeking for whatever it is led to their activation.

These are super interesting neurons because what they're essentially doing is they are providing a subconscious signal about the quality of the food that you're eating, what it contains, and then triggering the release of a molecule within your brain, dopamine, that leads you to go seek more of those foods.

So now I've mentioned two of the three mechanisms by which we prefer certain foods. One is from the actual taste that we're familiar with, the taste on our tongue and in our mouth and the sensations that make us go, "Mm," or, "Ugh," or, "Eh." The yum, yuck, meh responses as I referred to them earlier. And then there's this subconscious signaling coming from the gut that's really based on the nutrient content of the foods.

There's a third pathway, which is the learned association of a particular taste with the particular quality or value that a food has. And this is where things get really interesting and where there's actually a leverage point for you to rewire what it is that you find tasty and that you want to seek more of.

We are driven, meaning we have mechanisms in our brain that make us motivated to pursue more of what brings both a taste of sweetness, but also that brings actual changes in blood glucose levels up. Okay? So we are motivated to eat sweet things not just because they taste good, but because they change our blood sugar level, they increase our blood sugar level. What your brain, meaning what you are seeking when you eat, is not taste, is not dopamine, is not even a rise in blood glucose. What you're seeking, even though you don't realize it because it's subconscious, is you are seeking things that allow your neurons to be metabolically active. And this is fundamentally important for understanding why you eat, why you eat particular foods, and how you can change your relationship to those foods.

Now, earlier I referred to these circuits as wired to do something. And in biology, and in particular in neuroscience, we talk about something being hardwired or soft-wired. Hardwired meaning that it's there and it's immutable, it cannot be changed. Soft-wired meaning it's very amenable to change. The taste system and this general system of seeking particular foods similarly is hardwired to obtain certain types of nutrients. It tends to like sweet things. Most children naturally like sweet things, some more than others. So there's some hardwiring of preference, but there's also some soft-wiring in the system that allows it to change.

So the experiments that were done that beautifully illustrate that you seek out particular foods because of the way they taste, because of their impact on blood glucose levels, but also on their impact on the dopamine system, even if your blood glucose levels don't change. So here's the experiment. One group of subjects is given a sweet taste of a substance that also raises blood glucose levels, blood sugar, and dopamine goes up, not surprisingly. Second condition, separate subjects consume an artificial sweetener or a non-caloric sweetener. It is not preferred much over other substances, but it is sweet so it's preferred somewhat, and it does not cause an increase in blood glucose levels. And not surprisingly, dopamine levels don't go up. So initially we don't tend to like artificial sweeteners that much.

However, if subjects continue to ingest artificial sweeteners, even though there's no increase in blood glucose level, and therefore no increase in brain metabolism, dopamine levels eventually start to rise. And when those dopamine levels eventually start to rise, you've essentially conditioned or reinforced that artificial or non-caloric sweetener, and then subjects start to consume more of it and they actually get a dopamine increase from it. So that's interesting. It says that consuming more of these artificial sweeteners can start to tap into the dopamine system and lead us to seek out or consume more of these artificial sweeteners.

Now, there's another condition that's been explored, and that's the really interesting condition. And it's the condition where an artificial sweetener is paired with a substance that can increase blood sugar. But not because it tastes sugary like a normal sweet substance. The natural world scenario where this would happen would be drinking a diet soda, which contains no calories and therefore would not increase blood glucose, but is sweet, with a food that increases blood glucose. And when that happens, what you're essentially doing is tapping into the dopamine system. This non-caloric sweet- sweet taste is paired with it, and there's an increase in- in neuron metabolism. So you have all of the components for reinforcement, and as a consequence, you get, in a sort of Pavlovian conditioning way, a- a situation where later, when you ingest that artificial sweetener, you actually get not only the increase in dopamine, but you get alterations in blood sugar management.

I'll make this in the natural world context. If you ingest an artificial sweetener, say, drink diet soda while consuming foods that increase blood glucose, then later, even if you just drink the diet soda, it's been shown that you secrete much more insulin, the hormone that regulates blood glucose, in response to that diet soda. And the simple extract or tool from this is if you are going to consume artificial sweeteners, it's very likely best to consume those away from any food that raises blood glucose levels. So if you're going to enjoy diet soda, be my guest, but do it while, not while consuming food, in particular foods that raise blood glucose, because what these studies show is that they can disrupt blood sugar management by way of the insulin-glucose system.

Studies by my colleague, Alia Crum, in the psychology department at Stanford, have explored the bodily response in terms of insulin release and the release of other food and eating-related hormones, as well as overall feelings of satisfaction, et cetera, in groups of people that drink a milkshake and are either told that it's a low-calorie shake that contains, uh, various nutrients that are good for them or a higher calorie shake that has a lot of nutrients, et cetera. And what they found was that the different groups, and here, again, I'm being very general with my description of these studies, but what they found is that the physiological response, the insulin response, the blood glucose response, and the subjective measures of whether or not people enjoyed something or not, were heavily influenced by what they were told were in these milkshakes.

So blood glucose would go up, insulin would go up when people were told it was a high calorie shake with lots of nutrients, less so when people ingested a shake that was, uh, you know, that they were told had less nutrients, and so forth, when in reality it was the identical shake. This is incredible. This is a belief effect. This is not placebo, right? A placebo effect is different. Placebo effect is in comparison. It's where the control condition actually influences outcomes to a same or to some degree just like the experimental condition. This is a belief effect where the belief and the subjective thoughts about what a given food will do has a direct impact on a physiological measure like blood sugar and blood glucose. Okay?

So let's zoom out from this for a second and think about how we can incorporate this into adopting consumption of healthy foods that serve our brain health in the immediate and long term. What this means is obviously you want to consume foods that you like, but because brain health is very important and many of the foods that promote brain health perhaps are not the most palatable to you or desirable to you, if you want to eat more of a particular food because it's good for you, pair it with that other food that provides you a shift in brain metabolism, because that's really what your brain and you are seeking, even though you don't realize it.

How long will this take? Well, the data really point to the fact that even within a short period of time of about seven days, but certainly within 14 days, that food will take on a subjective experience of tasting at least better to you, if not good to you. Now, I believe this has important implications for much of the controversy and food wars that we see out there. Food wars being, of course, these groups that ardently subscribe to the idea that their diet and the things that they are eating are the foods that are good for us and that are the most pleasureful and the things that everyone should be eating. We see this with every community within the nutrition realm.

What's very clear, however, is that what we consume on a regular basis and what leads to increases in brain metabolism leads to increases in dopamine, and thereby our motivation to eat them. So what this really says is that what we tend to do regularly becomes reinforcing in and of itself, and I think in large part can explain the fact that yes, indeed, for certain people, a given diet not only feels good, but they heavily subscribe to the nutrient and kind of health beneficial effects of that diet.

What this emphasizes is that foods impact our brain and its health, but they- they also impact how our brain functions and responds to food. And that is largely a learned response. We can't completely override, for instance, that certain foods evoke a strong, "Ugh, yuck," component. Certain foods are truly putrid to us, but it's also true that if we continue to eat foods that are progressively sweeter and sweeter and highly palatable, it shifts our dopamine system because it activates our dopamine system to make us believe that those foods are the only foods that can trigger this reward system and make us feel good and taste, and that they taste good.

But after consuming foods that perhaps are less sweet or even less savory, that are not what we would call highly, or I would say nowadays it's super palatable foods, we can adjust our sense literally of what we perceive as an attractive and rewarding food. And indeed the dopamine system will reward those foods accordingly. Put simply, we don't just like sweet foods because they taste good, we like them because they predict a certain kind of metabolic response.

If you want to learn more about food reward and food reinforcement, 'cause it turns out those are slightly different things, there's a wonderful review written by Ivan de Araujo, they have a middle author, Mark Schachter and Dana Small. It's called Rethinking Food Reward, and it was published in the Annual Reviews of Psychology. You can find it very easily online. It was published in 2019, and it's a beautiful deep dive, although quite accessible to most people, about how different foods and the way that we perceive them impacts our brain and body and why we like the things we like and how to reshape what we like.

So once again, we've done a fairly extensive deep dive into food and your brain, came up with a relatively short list of what I would call super foods, and we also talked about food preference and why particular tastes and particular events within the gut and particular events within the brain combine to lead us to pursue particular foods and to avoid other foods, and how you can leverage those pathways in order to pursue more of the foods that are going to be good for you and good not just for your brain, but for your overall body health and to enjoy them along the way.