Welcome to the Huberman Lab Podcast, where we discuss science and science-based tools for everyday life. My name is Andrew Huberman and I’m a Professor of Neurobiology and Ophthalmology at Stanford School of Medicine. This podcast is separate from my teaching and research roles at Stanford, but is part of my desire and effort to bring zero cost to consumer information about science and science related tools to the general public.

In keeping with that theme, I’d like to thank the sponsors of today’s podcast. Our first sponsor today is Theragun, a handheld percussive therapy device that releases deep muscle tension. I was first introduced to Theragun in 2017 while on a laboratory expedition, filming great white sharks for my laboratory studies on fear using virtual reality. We were working very hard around the clock and I and other people on the trip were picking up a lot of aches and pains and just kind of chronic soreness. Couple of people had injuries that were flaring up because of all the hard work and lack of sleep.

Someone had a Theragun and it quickly became the most sought-after device on board. Everyone was using it to work on different areas of soreness, and I fell in love with it so much that I bought one when I got back and have used it almost daily ever since. I use it on sore muscles and to release tension and improve tissue quality. The great thing about the Theragun is that it is really quiet, so you can use it while in a conversation or watching a movie without disrupting those activities. If you want to try it, you can get the Gen Four Theragun for $199 at theragun.com/huberman. This is a great investment considering a massage typically costs the same and you can use the Theragun every day. The second sponsor of today’s podcast is InsideTracker.

InsideTracker is a personalized nutrition platform that analyzes data from your blood and DNA to help you better understand your body and help you reach your health goals. The great thing about InsideTracker is that it gives you data that you can make sense of. I’ve long been a believer in getting blood samples taken and more recently I’ve become a believer in getting DNA samples taken in order to understand what’s going on at the level of hormones, metabolic factors and other things that profoundly influence our immediate and long-term health.

The problem always has been getting those samples taken and making sense of those samples. InsideTracker makes all of that really easy. They’ll even come to your home to take the samples. Then you get the information back. And while typically after getting information back there’s these long lists of numbers and nobody knows what to do with them, InsideTracker makes it really easy to interpret what those numbers mean. And it points to things in terms of lifestyle, exercise, nutrition, and so forth that can help you adjust some of the numbers that you might need to bring down or up to put into the appropriate normal range.

So I find this whole process to be immensely valuable for guiding my health choices and also just for giving me peace of mind about how my body and the rest of my health are doing internally.

Something you just can’t know without a blood and DNA test. If you want to try InsideTracker, you can go to insidetracker.com/huberman, and you’ll get 25% off any of their programs, you want to put Huberman at checkout. So that’s insidetracker.com/huberman to get 25% off any of InsideTracker’s plans and put Huberman at checkout.

The third sponsor of today’s podcast is Athletic Greens. Athletic Greens is an all-in-one vitamin mineral probiotic drink. I started using Athletic Greens in 2012. So I’m delighted that they’re a sponsor of the podcast.

The reason I started using Athletic Greens and the reason I still take it once or twice per day, is that I find it very hard to know what vitamins and minerals I need to take. And by drinking Athletic Greens, I get it all in one easy to consume great tasting formula. I really do like the way it tastes.

I mix mine with water and a little bit of lemon or lime juice. To me, it’s delicious. The other thing I like about Athletic Greens is the probiotics. There is a lot of data out there telling us that probiotics are important for supporting the gut microbiome, the gut-brain axis, the immune system, and many other aspects of our biology. With Athletic Greens, I get the vitamins, minerals, and probiotics that I need.

If you want to try Athletic Greens, you can go to athletigreens.com/huberman. If you do that, they’ll also give you a year supply of vitamin D3K2. Vitamin D3 is also important for things like immune system and metabolic support. So, that’s athleticgreens.com/huberman to get Athletic Greens and a year’s supply of vitamin D3K2, plus five free travel packs.

Today, we’re talking all about emotions, which are central to our entire experience of life.

Whether or not we’re happy or sad, depressed or angry is our life experience. With all the importance we’ve placed on emotions, very few people actually understand how emotions arise in our brain and body. It also involves events, biological events, and chemical events within our body.

The other thing about emotions is that there’s no real agreement as to what’s a good emotion or a bad emotion. Today we’re gonna talk about the biology of the chemicals and pathways that give rise to emotions and equip you with several, if not many, tools that will allow you to regulate, change, and steer your emotions should you want, but not using the typical advice.

Smiling can’t reverse depression or sadness, but certain things that are happening in our body can influence how our brain functions and the chemicals that are released. This is why we’re talking about how food and nutrition can impact emotions. Ingesting certain macro and micronutrients can affect the chemicals in our brain that give rise to feelings of being happy or sad, sleepy or alert. We’re not advocating any particular diet regimens, but rather reviewing the most important scientific data that points to how these nutrients can affect our emotions.

This is sure to be a broad discussion, yet we’re going to get very specific about what emotions are, how they arise in the body, and tools that one can use in order to better control their emotions. We can use these tools to feel happier or calmer, as there has been an explosion of scientific studies in the last two decades exploring how the brain and body interact to support certain neurochemicals that give us these feelings. We will make this information clear and provide links to several of the studies. The goal is for you to understand how moods and emotions arise, the pathways in your brain and body that allow them to happen, and how you can use those pathways to change those emotions. We will also discuss specific tools that you can rely on to shift from feeling slightly depressed to feeling happier, or from feeling too alert and anxious to feeling calmer. These are distinct from the tools discussed in previous episodes. The discussion around emotions has a long and rich history going back to Darwin.

The idea that emotions are universal and that some of the facial expressions around emotion are universal has been a conversation that philosophers and scientists have had for hundreds, if not thousands, of years. Darwin put forth this idea, which has been attractive for the last hundred years, and others have capitalized on it. To some extent, it is true. For example, when we experience something we like, we tend to posturally lean in, inhale air, and make mm’s. When we experience something we don’t like, we either lean back or look away, or we intensely cringe our face and avoid inhaling any of the chemicals.

The roots of emotion likely have their origin in ancient biological mechanisms designed to prevent us from ingesting things that are bad for us. Chemical compounds and tastes that may be poisonous can be avoided through this push-pull of attraction and aversion. This basic way of thinking about emotions can be applied to many different circumstances, from the deep circuits of the brain to the more evolved centers.

We can think of this push-pull as delight or happiness being attractions to certain things, while aversion is a leaning out, a disgust or avoidance. At the core of this attraction or aversion is the fact that there is an action taking place, either moving forward or away from something.

Any time you’re talking about action in the nervous system, you’re talking about motor behaviors – the contraction of muscles to move you toward or away from things. You’re also talking about the brain and the body, because the brain can’t move itself – it has a body so that the organism can move.

Some of the things we’re attracted to and some of them that we avoid are what we call innate or hardwired. We tend to avoid bitter compounds because they’re associated with poisons, and we tend to pursue more of sweet or savory things. There are circuits in the brain for aversion and for attraction toward things.

The vagus nerve is actually a nerve that runs from our brainstem down through our body and it’s responsible for regulating a lot of our physiological functions.

The vagus nerve is one, not the only, but one way in which our brain and body are connected and regulate our emotional states. Polyvagal theory, popularized by Stephen Porges, is an interesting theory, with certain aspects of it holding up to the science and some of it not. The vagus nerve is a nerve that runs from our brainstem down through our body and is responsible for regulating a lot of our physiological functions. It has somehow gotten into the public’s mind that the vagus is involved in calming us down. A lot of the excitement about the vagus is because of this. However, it is important to understand the real power of the vagus nerve and not to oversell or undersold it.

The vagus nerve is the 10th cranial nerve which sends a wire into the brain. It also has a branch that goes into the periphery, including the stomach, intestines, heart, lungs, and immune system. The vagus nerve has two directions: sensory, which senses things happening in the gut, lungs, and heart rate, and sends that information up into the brain; and also consents things in the gut like how distended or empty the stomach is. It can also sense the immune system, whether or not bacteria or other invaders are present.

The vagus is a two-way street, sending sensory information up to the brain and motor control in the other direction. It is not just for sensing, but also for controlling things. Everyone should know this, as it is as important as knowing how to walk. The vagus is the way in which you can govern the brain-body connection.

The vagus nerve is a super highway within you that connects sensory information from all the different organs of the body up to the brain and motor information from the brain back to the body. It is often thought that certain behaviors such as rubbing your face or breathing in a particular way can stimulate the vagus, however this is not the case. If there are contaminants in the body, the vagus will sense this and project it to the brain in order to generate a fever and try to kill the contaminant. Therefore, it is not wise to simply stimulate the vagus. Instead, it is important to understand how to activate particular circuits and pathways from certain organs to the brain in order to feel better or relieve certain conditions.

Excitement about the vagus is partly due to Stephen Porges’ polyvagal theory. This theory acknowledges that the vagus has many different branches, rather than just one. Porges put forward the idea that there is a dorsal vagus, which is involved in alertness and fight or flight type responses, and a ventral pathway which is involved in empathic behaviors. This is not in agreement with modern anatomy, but Porges was doing the best with what he had.

The problem with the polyvagal theory is that it is often discussed in a way that suggests that if the dorsal vagus is too active, then the person is too keyed up, while people who are in a state of freeze or lethargic have an inactive ventral vagus.

The pathway of the vagus is hypoactive and should be more active. There are many theories about how psychology maps onto the vagus, however, these do not map to any real physiology. Additionally, people often diagnose psychological and physical manifestations through the vagus, which is not accurate. To simplify our understanding of how the vagus works, today we will discuss the vagus in 2021.

The vagus nerve is like the eyes of the body. Just like the eyes detect light, color, motion, and brightness, the vagus nerve senses various features within the body, such as how full the gut is, how acidic it is, how fast the heart is beating, how full the lungs are, and the status of the immune system. This information is then communicated to the brain, which can use it to decide when to be awake or asleep, and whether or not someone is attractive or unattractive. The vagus nerve is constantly analyzing many features within the body and informing the brain of how to feel about that and what to do.

Sweet foods generally taste good, so people want them. What’s interesting is that for hundreds of years people have thought that this is because of the way that sweet foods taste. However, recent research has shown that it’s actually because of the way that sweet foods look. People find the bright colors and shapes of sweet foods attractive, which is why they want them. I’m not particularly a fan of very sweet things, but I do like sweet foods. I’d much rather have cheese, pizza, hamburger, or steak.

Eating something sweet triggers a complex series of reactions in the body. Cells, neurons, and sensors in the stomach detect the presence of sugary foods and send information up the vagus nerve to the brain. This triggers the release of dopamine, a molecule that makes us want more of what we just ate. Experiments have even been conducted where people are blindfolded and can’t taste the food they’re eating, yet still crave more of the food that contains sugar due to the sensors in the gut.

We actually have sensors within our body that make us crave sugar independent of the sweet taste of those things. This is incredible, as it tells us that we have circuits in our body that are driving us towards certain behaviors and making us feel good even though we can’t perceive them. For those of us interested in gut intuition and gut feelings, this is a gut feeling, except this is a chemical gut feeling. This is a particular set of neurons detecting that something in our body has a particular feature, in this case the presence of sugars, and sending information to the brain to control our behavior.

What this means is that what we call attractive isn’t always coming from our thoughts, feelings, or perception. We are drawn to particular foods and people, places, and other things because of information coming from our body. Many people are concerned about sugars these days, thinking we all ingest too much sugar, as it is snuck into all the things we eat. We will discuss what one can do with this information.

The research suggests that even if a food is very savory, like a piece of pizza, bread, or salad dressing, if there is sugar snuck into it and you can’t taste it, you will still crave more of that thing without knowing why. This can lead to wanting certain foods and not understanding why. This relates to mood and emotion, and we can ask why do we eat certain things and why do certain foods make us feel good, while others make us feel anxious?

Most people don’t realize that as you approach eating, there is an anxiety associated with that. This anxiety is part of a continuum of alertness versus calmness. We often hear about the concept of rest and digest, where after eating, we feel relaxed, satiated, and full. This is associated with serotonin, a molecule of satiation. What is lesser known is that there is an area of the hypothalamus called the lateral hypothalamus which plays a role in this process.

The lateral hypothalamus is an interesting area of the brain as it controls feeding, but it also inhibits feeding. There is another area of the brain, the locus coeruleus, located in the brainstem, which releases norepinephrine (also known as adrenaline) and makes us feel alert. This area of the brain is known to release noradrenaline when we are about to eat, creating a feeling of alertness. For many people, this can be experienced as stress or anxiety.

Locus coeruleus is a part of the brain that releases molecules that make us feel anxious and alert when we approach food. This heightened stress can lead to difficulty in calming down and having a good meal. To combat this, tools such as mindfulness around meals can be used, as well as understanding our relationship with food and our feelings towards it. For those who cannot avoid being stressed while eating, it is important to recognize that this is normal and to try to be mindful of our eating habits.

I don’t generally take time to do two or three deep breaths before I eat; I generally will just eat. This can be both healthy and unhealthy depending on the quality of your digestion. I think using digestion as a guide is good, but a lot of people aren’t aware that the interaction between the locus coeruleus and lateral hypothalamus is a basic mechanism that is supposed to make us a little bit alert and anxious around mealtime. As we eat, the mechanisms for calming and satiation are supposed to kick in. These involve two things: how things taste and digestion starting in the mouth. Everyone tells us we should chew our food more, which can improve digestion. Additionally, we’re not supposed to drink too many fluids as we eat.

A lot of how we feel while we eat and after we eat is because of the vagus sensing of what’s in our gut. It’s sending information all the time – is there sugar, fats or contaminants? This information is sent up into our brain through parallel pathways which regulate whether or not we want to eat more of something. There are accelerators such as sugar, fats and amino acids which make us want to eat more as they are nutrient dense and help support the survival of animals, at least in the short term.

There are a lot of data on what people eat and how much they eat, which comes from a subconscious detection of how many amino acids and what the array of amino acids is in a given food. It is believed that people will eat not until their stomach is full, but until the brain perceives that they have adequate intake of amino acids. This conversation usually comes up in the context of diets such as the keto diet, zone diet, Mediterranean diet and vegan diet. These diets each tap into something important about the brain-body relationship, but the focus today is on nutrient and amino acid sensing. We generally eat until our gut tells our brain that we have adequate amounts of amino acids, which are important for building muscle and other things in our body that need repair.

But I have a really
strong affinity for ice cream.

Amino acids are what the neurochemicals in the brain are made from, and this is vitally important. We have heard that dopamine is a molecule that makes us feel good. It is released within the brain, and it does feel very good when it is released due to surprise, excitement, or events that turn out well. On the other hand, it is inhibited by events that don’t work out as expected, such as when someone says they will call, but then don’t. This is known as reward prediction error, and it can be used in a useful way with yourself and people you know. If you expect something to be really terrific, it places a higher expectation at the chemical level. If you don’t get as much dopamine as expected, it can be disappointing. For example, I have a strong affinity for ice cream and if it doesn’t live up to my expectations, it can be a letdown.

I would call it more of an affliction for croissants: the best vegetable of course, is the croissant. I get really excited when someone tells me about a place with incredible croissants. This raises an expectation, a dopamine expectation, and unless those croissants are amazing, chances are I’m going to experience them as less good, less satisfying. This is because of a reward prediction error: my expectation of something releases dopamine, and the actual event releases dopamine. If the event-related dopamine does not exceed the expectation or at least match it, there is a much higher tendency that I won’t pursue that thing again.

Dopamine is a powerful molecule that is not just the molecule of reward, but also the molecule of desire and wanting. A book that I highly recommend to learn more about dopamine and its role in regulating emotions and motivations is “The Molecule Of More”. It is a terrific read that covers topics such as reward prediction error and how dopamine affects our cravings. In short, dopamine is what drives us to want more of something or not want more of something.

Our gut contains amino acid sensors that detect how many and which amino acids are present. One of these is called L-tyrosine and is found in meats, nuts, and some plant-based foods. L-tyrosine is the precursor to molecules like L-DOPA and dopamine, which are thought to influence mood. However, most of the serotonin and dopamine are not in our gut, and so our mood is not solely determined by what is in our gut.

Dopamine is synthesized from the amino acids that you eat. However, the dopamine neurons that give rise to feelings of good, wanting more, desire, and motivation reside in the brain. This means that some people make too little dopamine and need prescription dopamine, such as L-DOPA, which is taken by people with Parkinson’s. Parkinson’s is associated with deficits in movement, which starts as a tremor, and is a depression.

It’s a blunting of motivation, mood, and effect and it’s a tremor. In severe conditions, it can lead to challenges in speaking and walking. Famous examples include Muhammad Ali, Michael J. Fox, and the great boxing trainer, Freddie Roach.

Parkinson’s is not exclusive to fighters and is caused by a depletion of dopamine neurons in the brain. It can also lead to mood challenges. Dietary L-tyrosine supports the healthy production of things like dopamine and other factors within the brain.

Some people immediately ask if they should supplement L-tyrosine. Hopefully, none of you have Parkinson’s, but it is important to be aware of the effects it can have.

L-tyrosine is an amino acid that can be taken to increase dopamine levels. It is available over the counter in capsule form, however people with preexisting hyper dopaminergic conditions like mania should not take it. It can cause a crash and a lethargy and a kind of brain fog after the next day or so. It can also be ingested through foods or through supplementation. It is important to check with your doctor before taking L-tyrosine to make sure it is safe for you.

Dopamine pathways can be disrupted when taken chronically. To combat this, there are drugs that increase L-tyrosine and dopamine levels, but these drugs often have addictive properties, such as methamphetamine and cocaine. An alternative to these drugs is the ingestion of L-tyrosine, which can have a profound effect on dopamine levels and mood, although it may take a while to take effect. Certain antidepressants, such as Wellbutrin, also affect dopamine levels, and are sometimes preferred over other antidepressants due to fewer side effects and lethargy.

Wellbutrin activates dopamine and epinephrine, which is a substrate of dopamine. Both of these are involved in motivation, alertness and effort. This drug has a side effect profile associated with elevated mood and alertness such as anxiety, sweating, and pupil dilation. It has been used somewhat successfully for smoking cessation, but it is not for everyone. I am not advocating for the use of these drugs, I am simply describing the biology and rationale for why they were developed.

It’s that they’re impacting our brain in ways that we don’t even understand or appreciate.

We have a brain-body connection, with one of the main ones being the vagus nerve. The vagus collects information about breathing, heart rate and what is happening in the gut and sends this information up to the brain. The brain then uses this information to decide whether to move towards something or away from it. Foods rich in L-tyrosine give us an elevated mood and make us want to do more of whatever activity we are doing, as well as other things. This motivation generalizes to other activities, not just ingesting food. However, a lot of this is happening at a subconscious level, which is why the concern about hidden sugars and over-ingestion of sugars is serious, as they are impacting our brain in ways we don’t understand or appreciate.

Obesity is not the only crisis happening; it is also disrupting our dopamine systems. Although some people have a healthy relationship to sugar, most people are unaware that it is affecting their neurochemicals subconsciously. Additionally, there are other pathways between the brain and body that regulate our moods and emotions and are actionable, such as serotonin. Serotonin creates a bias in which neural circuits and neurons in the brain and body are active. For example, my bulldog Costello’s brain and body must be swimming in serotonin, as he is very calm and eats a lot, yet feels sated. He is a hedonist and when serotonin is elevated, it makes us feel comfortable and blissed out.

Serotonin is a neurotransmitter that contrasts with dopamine and epinephrine, which mainly put us in pursuit of things. Motivation is pursuit. Serotonin, on the other hand, is more about feeling really comfortable where we are. The conversation around the brain-body relationship and mood, and serotonin in particular, for many years was that eating a big meal and having the gut distended with nutrients would result in serotonin being released. However, there is a lot more going on and a lot more that is interesting and actionable. It is important to note that more than 90% of the serotonin that we make is in our gut, and we have neurons in our gut that make serotonin.

Serotonin is a neurotransmitter that impacts our mood and mental state. It is primarily found in the raphae nucleus of the brain, as well as a few other locations. Discussion of serotonin often leads to discussion of antidepressants, such as Prozac, Zoloft, and Paxil. These are known as selective serotonin re-uptake inhibitors, and they work by preventing the re-uptake of serotonin into neurons after it has been released, leading to more serotonin overall. While these drugs can be useful for people with depression and other clinical disorders, they are not suitable for everyone.

Medications can be quite useful for many people, however not everyone responds well to them. Their side effect profile can include blunting affect, making people feel flat and reducing appetite for food and sex. It can also work really well, and this can be dose-related. Serotonin is fascinating because how well the neurons in the raphe work is impacted by events within the gut, which may surprise you. Let’s go a little deeper into the gut.

The gut includes the stomach and small intestine, and the large intestine. We can ask questions about how serotonin in the gut is impacting serotonin in the brain. We can think about this in the context of how we might want to increase or decrease our serotonin levels. Unfortunately, there aren’t any good at home blood tests for serotonin and dopamine. There are some commercial products, but they are not as reliable as getting your hormones levels or metabolic factors measured. Fortunately, there are tests out there that can be done rigorously.

There are some questionnaires that attempt to measure whether someone is more of a dopamine or serotonin type. I find this kind of silly, although I do appreciate that people are thinking and talking about neuromodulators. Unfortunately, there is no great way to measure these things outside of a clinical setting, although there are some great clinical tools available from a hospital or endocrinologist. This could be a call to arms for entrepreneurs to create accurate at-home tests.

Many people adjust their serotonin levels by eating more food, particularly carbohydrate-rich foods. I personally prefer to fast and exercise in the morning and eat a high-protein, moderate-fat, low-carb meal in the afternoon to stay alert. This favors dopamine, acetylcholine, and epinephrine production and alertness. In the evening, I focus on getting a good night’s sleep.

I will ingest foods that promote serotonin release because they contain a lot of tryptophan. For example, if I do eat meat, it would be white meat, such as turkey. However, I don’t tend to eat turkey as I don’t like the taste. Starchy carbohydrates can also increase serotonin. Some people take serotonin supplements, such as 5-HTP. This can be tricky as it can create problems with endogenous production of serotonin. Therefore, I am not a fan of taking substances very close to the chemical you are trying to increase for long periods of time.

Maybe occasional use of serotonin supplements, such as 5-HTP, can be beneficial. However, taking it early in the night can disrupt the pattern of sleep and the depth of sleep. Some people are interested in taking serotonin to get more blissed out effects, but this can also be achieved with foods that are carbohydrate rich. This discussion is not about nutrition per se, but rather about food which contains amino acids, which are precursors to neuromodulators. Neuromodulators have a profound effect on overall state of alertness, calmness, happiness, sadness, and wellbeing.

One of the things that one can take is 5-HTP itself. I’m not recommending people take anything, but if you’re interested in what this does and you want to explore this, you should get permission from your doctor. I love the free website examine.com, which has links to all the PubMed studies for particular effects of particular compounds, as well as important health warnings. If you go to examine.com and search for 5-HTP, they are only looking at things that have strong evidence.

Research has found that 5-HTP produces a notable decrease in appetite. This makes sense because serotonin is produced by ingesting foods, and if there is enough serotonin present, there is no need to ingest more. This appetite suppression could be an interesting route for someone looking to blunt their appetite, although chronic use is not recommended. Additionally, there is a decrease in body weight and an increase in cortisol as a consequence. This is typical in biology, as pulling on one string often causes another to move. The increase in cortisol is reported as a minor effect.

There are links to all these resources available at examine.com. So I find it fascinating that nowadays there are things that are somewhere between doing nothing, getting serotonin from tryptophan and foods, and prescription drugs. There’s this other category of supplements that are really interesting for modulating these chemicals in the body. Before I move on, I should mention that I neglected to mention earlier in our discussion about dopamine, if you’re interested in the dopamine pathway, go to examine.com, put in Mucuna pruriens. It is a velvet bean that grows from vines and is very itchy to touch due to serotonin on its surface. Inside the bean is L-DOPA, and it contains some other molecules as well and low levels of other psychoactives. All these resources are available at examine.com.

This stuff is available over the counter and I personally find it incredible. Its effects are really interesting. I’m not going to read them all off, but I mentioned them not because I’m encouraging you to take it, but because you get a window into what dopamine, acute dopamine increase does in the non-Parkinsonian context. You can start to think about foods that are rich in L-tyrosine as biasing certain effects or not others. So when you hear “food is medicine”, food isn’t really medicine, but food has these chemical effects as well.

The first one listed is three studies with very high rigor that overall have a minor effect on sperm quality. I’m assuming that when they say sperm quality, they looked at features such as sperm motility, as I know enough about reproductive biology to know that sperm ability to swim depends on some proteins that are present in the front of the sperm, such as contractions and sperm motility, which is generally associated with sperm quality.

Sperm that don’t move are generally not very useful sperm. Symptoms of Parkinson disease are notably degraded with Mucuna pruriens. So fascinating! That’s not surprising, and there are a lot of other effects here. Feelings of subjective wellbeing, increased testosterone, and reductions in prolactin are not surprising. Prolactin is a hormone that’s involved in milk letdown in lactating mothers, and it’s involved in feelings of peace and generally is antagonistic to sexual desire in both men and women.

It’s really interesting that things like Mucuna pruriens, which are L-DOPA, reduce prolactin, increased sperm motility, increased testosterone, and subjective wellbeing. So you’re starting to see a theme, right?

Dopamine makes us motivated and feel in pursuit, which makes us feel good. Serotonin makes us feel more relaxed and calm. This whole month is about emotion and so far we have been talking about good and bad emotions. However, we can’t really say an emotion is good or bad – there is a social context to it. For example, grieving at a funeral is healthy and acceptable.

It’s just something that I’ve read
and I highly recommend it.

Being happy at a funeral, assuming you loved the person that died, is something that many people wouldn’t think is healthy. However, it is important to consider the context and culture when it comes to emotions – there is no one-size-fits-all approach. Many people have asked for book recommendations and I would like to mention Lisa Feldman Barrett’s book “How Emotions Are Made”. I learned about her from the Lex Fridman Podcast and have had discussions with her on my Instagram Live. She is a world expert in emotions and is based at Northeastern University. I have read the book and highly recommend it – I have no financial affiliation with the book.

I paid for this book with my own money years ago and bought, read and loved it long before I met Lisa. I’m delighted that we’ve got to know each other a little bit. It is a really interesting read into the psychology of emotions and the subjectivity of emotions. Whereas I’m talking mainly about the biology of emotions, this book gets into the psychology and biology as well. Lisa is terrific and puts a lot of information out into the world about emotion. If you want to learn more, check out her work – Lisa Feldman Barrett – and her book, “How Emotions Are Made”. Hopefully she will continue to write many more books.

Now you understand the relationship between foods and dopamine, foods and serotonin, and how they are both communicated to the brain via the vagus. We ingest these foods or take supplements, but they don’t go directly into the brain. Instead, they are put into our gut.

Yes, there is a gut-brain connection, but it is not about the serotonin in the gut that makes you feel calm and placid. In fact, the idea has been oversold. There is something attractive about believing that because certain aspects of our experience of life and emotions are happening in our body, we may have a little more control. Unfortunately, we cannot stuff dopamine into our bodies. Even if we were to stuff a Mucuna pruriens bean into our ear, it would not help; it would just make our ear itchy because of the serotonin on the outside.

You have to ingest things that are metabolized in certain ways that communicate to the brain, or so maybe they pass into the brain themselves across what’s called the blood brain barrier (BBB). The BBB is also responsible for nerves in the gut that sense the nutrient contents of food and then send signals to the brain that either make us feel better or want more. For example, if food has a lot of bitterness and acid taste, we should want less of that.

I hope this discussion of dopamine and serotonin in the gut has given you some actionable items. You can now understand how certain foods and nutrients can impact your mood. If you’re somebody who’s really anxious and wired, it’s probably best to avoid leaning on the dopamine/epinephrine pathway any harder.

If you tend to be someone who’s pretty passive and having trouble with motivation, then ramping up the dopamine pathway through behaviors and proper food choices is the best way to start. Behaviors include things like exercise. However, the discussion around mood and exercise or mood and meditation is subjective – certain forms of exercise are aversive to some, while attractive to others. No one has ever told us exactly how much exercise we need to do in order to get our dopamine up. However, ingesting more L-tyrosine has a high probability of making more dopamine.

Mucuna pruriens was too dopaminergic for me; I got really jazzed up and then had a severe crash the next day. I think this is because I tend to ride pretty high on the alertness and motivation scale, and could probably afford a little more serotonin in my life. Costello, on the other hand, can afford to wake up every couple of days and just say hello to us. This dog sleeps more than any other creature – it’s remarkable. Ingesting Mucuna pruriens through food or supplementation may be beneficial for some, but I would suggest being aware of potential side effects.

There are things we can do to shift our mood, and they are actionable. We can regulate dosages, amounts, and timing, and everyone has to find what works best for them. Exercise is still important, as is social connection, and what we eat matters when it comes to the neurochemicals our body produces. I have been doing this for years and I have found it to be a complete game changer. There is excellent science to support this.

The omega-3 to omega-6 fatty acid ratio has a profound effect on depression and mood. In a double-blind placebo controlled study, first published in 2008, they found a model of learned helplessness in animals. They put rats or mice in a jar and let them swim to try and save their life. Eventually, they give up, which is a learned helplessness. Adjusting the omega-3 omega-6 ratio so that the omega-3’s are higher led to less learned helplessness, meaning these animals would swim longer. There have been many other studies as well.

A recent study on rats showed that the same study was essentially done on humans. The study took people who were clinically depressed and compared a thousand milligrams of EPA (an element found in fish oil) to 20 milligrams of Fluoxetine (Prozac). The study of 60 individuals found that both treatments were equally effective in reducing depressive symptoms.

Imagine a food-based compound that you can’t make without. This compound, when taken in combination with 20 milligrams of fluoxetine over the course of eight weeks, was as effective as the fluoxetine alone in lowering depressive symptoms. This remarkable discovery was made even more interesting when it was found that the combination of a thousand milligrams of EPA and fluoxetine had a synergistic effect.

When I first heard about this discovery, I wasn’t sure what to make of it. I like to focus my behavior changes around things where there is a large center of mass, and I wanted to make sure there was enough information before I started taking the fish oil. A couple of years later, I began taking a thousand milligrams per day of EPA in fish oil. However, it is important to note that people who have blood clotting issues, such as Factor V Leiden mutations, or women who are taking birth control, should talk to their doctor to make sure it is safe for them to take fish oil.

Fish oil can give people fishy breath, which is pretty gross. Fortunately, there are now fish oils that don’t have this effect due to encapsulations or lemon flavoring. I started ingesting 1000 milligrams per day of EPA and noticed an increase in my mood and affect. It is also supposed to reduce inflammation and the cardiovascular effects are controversial. For a long time, it was thought that the effects on platelets were really good, however, recent articles have cast doubt on this. Nevertheless, studies have shown that fish oil can be as effective as certain SSRI antidepressants at these dosages and can amplify or improve the effect of low dosages of some of these SSRIs. Therefore, more people should be aware of this.

Depression can have many components, including anxiety, uncertainty, and certainty. When someone is anxious, they can be reassured that everything will be okay, but they often fixate on the uncertainty of the future. On the other hand, there are versions of depression that involve certainty, where people are lethargic and certain that they will never get another job or meet anyone new.

I’m certain I’m gonna fail. So, there’s this kind of divide in the sphere of depression around certainty and uncertainty. What’s interesting is that a thousand milligrams per day or more of EPA has been shown to relieve both forms of depression. I’m not here to try and play psychiatrist, but I want to point you in the direction of these manuscripts so that you can make informed choices for yourself. You can discuss it with your doctor and family and make the choices that are right for you.

Here’s what’s especially interesting about the heart effects, because we’ve heard that these omega-3s, which of course you can get from other sources too, you can get from fatty fish, they’re in flax seeds, hemp seeds, a number of chia seeds, these kinds of things. But the levels of EPA that are required are quite high, so this thousand milligrams per day is pretty hard to get from food, although it can be done depending on what you’re eating.

Interesting research has shown that people who have a higher heart rate variability tend to have better health outcomes overall. This is linked to the tone of the autonomic nervous system, which we discussed in a previous episode. When you inhale, your heart rate increases, and when you exhale, it decreases. This is important for overall health, as those with higher heart rate variability tend to have better health outcomes.

Respiratory sinus arrhythmia is the basis of heart rate variability (HRV). We may post a short article about this to explain the mechanisms and behaviors that can be beneficial. HRV is generally good, and a 2009 study showed that people who eat a diet low in omega-3s tend to be unresponsive to antidepressants. Increasing the amount of EPA and shifting the ratio to a higher omega-3 to omega-6 ratio lowered inflammation markers and allowed antidepressants to have their effect even at low doses.

Here’s the really interesting thing: it worked by increasing heart rate variability. You may be wondering how this could be possible. It works by impacting the gut and the autonomic nervous system. The vagus nerve includes connections from the heart to the brain, which signal information about how fast the heart is beating. The brain then adjusts the heart rate by increasing heart rate variability.

Ingesting more EPA’s, either through food or supplementation, can increase rate variability and improve symptoms of depression. It is even possible to make low levels of antidepressants work. This study is so interesting because it bridges the brain-body connection, incorporates nutrition and micronutrients in the brain, and emphasizes that our body is a whole system. The brain is not isolated in the skull, but instead reacts to things happening in the body, such as the gut and heart rate.

The things we ingest can have a profound effect on our wellbeing. No one compound, nutrient, supplement, drug, or behavior is going to be the be all end all of shifting out of depression or improving one’s mood or sleep. It is a constellation of things, especially when people start to get excited about supplements and drugs. There is currently a lot of excitement about psychedelics and their therapeutic uses, but as a good friend of mine who is a physician clinician said, “better living through chemistry still requires better living.” Taking a compound, regardless of source or potency, cannot completely shift one’s experience of life without having to continue to engage in proper behaviors such as sleep, exercise, social connection, and food. I find the collection of studies about omega-3 to omega-6 ratios to be profoundly important, and it has changed the way I think about food and the foods I eat. I supplement, but I don’t necessarily think that’s for everybody. It is incredible that there are these compounds that have robust effects on our feelings of wellbeing.

There are others too that one might want to take in order to get the benefits of fish oil without actually taking fish oil. The threshold of 1,000 milligrams per day of fish oil that is beneficial requires that one take a reasonable amount of it either through food or through supplementation.

I acknowledge that not everyone wants to take fish oil for a variety of reasons. One might be for ethical reasons, such as having an emotional relationship or a relationship to the environment that makes them not want to ingest fish related products. As an alternative, there is krill oil. Krill is still an organism, a little tiny thing that whales eat a lot of and people generally eat very little of. Personally, I did not react well to krill oil, but there are others that one might want to take in order to get the benefits of fish oil without actually taking fish oil.

I had a bad experience with krill oil and it didn’t make me feel very good. I had some kind of skin itches and other symptoms that stopped when I stopped taking it. However, I do not want to bias you against it, as some people really like it as a source of omega-3s. I did mention other sources, like chia seeds and flax seeds, but these are not regularly ingested. It is possible to get omega-3s from meats, as long as the animals have grazed on grasses that contain omega-3s. For those that ingest meat, the source is important as it relates to omega-3s. Even within the category of fish oil, there is a concern about mercury and other contaminants.

When looking for a brand of fish oil, it is important to go with one that emphasizes they’ve gone to good sources and decontaminate. To test whether the fish oil is rancid, people can take it in either liquid or capsule form. Liquid form is more affordable, while capsule form is easier and more portable. If the gel tablet tastes fishy and rancid, it should be spit out.

Unfortunately, you have to purchase it first in order to do that. Although, I don’t know, maybe you can get them to open up the bottle for you in the store and tell them you want to try it. Someday, perhaps, fish oil and omega-3 will be like tasting wine at a restaurant, where you can send it back for now. I think you have to purchase it first, but find a brand you trust, and then work with them. If you decide to go that route, of course.

There are other compounds that are also interesting for mood elevation that are essentially like foods or are supplement based. Now, fortunately, there are really good data from peer reviewed studies. The next one I want to mention because I think it’s really interesting is L-carnitine. Now, L-carnitine has been around a long time and it’s been discussed in the context of heart health and a number of other things. It was actually being touted as a bit of a weight loss agent in the early nineties, but L-carnitine actually has some really impressive effects on depression.

L-Carnitine is most prevalent in meat and beef in particular. For vegans, it is available through non-meat sources, although it is not as enriched. Acetylcarnitine is essentially what is made from L-carnitine, but it is acetylated and can cross the blood-brain barrier (BBB). The BBB is a wall around the brain that is important because neurons don’t recreate themselves after injury like other organs of the body, despite what you might have heard.

Nature has created the blood-brain barrier and the blood gonadal barrier to protect the brain, ovaries, and testes from large molecules that could be damaging to these organs. L-carnitine, when taken, is acetylated and converted into a form that is able to cross the blood-brain barrier. It has a number of effects, including mitochondrial activation of long chain fatty acids, and effects on ammonia, C-reactive proteins, blood glucose, and cholesterol. Studies show that rates of pregnancy go up when both the father and mother take L-carnitine, as the source of sperm and egg are affected in ways that favor pregnancy.

L-carnitine has been found to increase sperm quality and motility in males and have positive effects on females with polycystic ovary syndrome. Studies listed show that the effects are strong and have been published in peer reviewed rigorous journals. Additionally, there are emerging effects on depression, with seven studies listed on examine.com showing that participants have felt a notable decrease in depressive symptoms after taking L-carnitine.

And they talk about dosages in those various studies. It also has been shown to have a notable decrease in the symptoms of autism, which I find fascinating. Also again, the things we ingest impact the chemicals in our brain and how they impact the rest of our body.

There’s other things that’s been used to treat certain forms of alcohol dependence. I think this is going to be a very exciting emerging area. We’re gonna do a whole month about addiction. I’ve got a great guest lined up for that month, but there’s now an emerging field about what people can take and supplement to help ease the cravings and the withdrawal when trying to quit drugs of abuse, like cocaine, alcohol, heroin, and smoking and things of that sort.

So really interesting area. This is, I like to think is the early days and we’re gonna discover a lot more. There’s a huge list of things here.

L-carnitine has been shown to reduce symptoms of fibromyalgia. On a previous episode, we talked about pain and a lot of people have written to me about fibromyalgia. All the links to studies can be found on examine.com, a totally free site.

Now let’s turn to another aspect of the gut-brain relationship that may surprise or even shock you. This has some really cool and actionable biology.

The gut microbiome, probiotics, and prebiotics have been linked to emotional wellbeing. Acetylcarnitine has also been reported to have an effect in reducing the symptoms of migraine. This was demonstrated in a randomized controlled trial with 133 participants who had frequent migraines. The participants took 500 milligrams of L-carnitine or nothing for 12 weeks. The results showed a significant effect on reducing the number of migraine attacks per month. There are many more potential benefits of these compounds, however, it is important to consider the risks for certain people. Ultimately, each person needs to decide what is right for them.

Today we have been talking a lot about the gut-brain axis, which has nothing to do with microbiomes. We have discussed the vagus nerve, which provides sensory information from the body to the brain, and also sends motor information to control the motility, heart rate, breathing, and deployment of immune cells.

When we hear about the gut-brain axis these days, it is usually in the context of the gut microbiome. While there is a lot of interesting biology here, I am concerned that much of what is discussed is either false or partially false. Therefore, we will first discuss the biology, and then move on to actionable items.

It is true that we have a lot of microorganisms living in our gut. However, they are not there to help us; they are there to help themselves.

Microbes don’t have brains, however they are adaptive and actively seek out and create environments that are beneficial for their proliferation. In the same way that viruses hijack cells and use the genome to make more of themselves, microbes exploit us to make more of themselves. Our digestive tract is made up of a series of tubes and our brain is also a tube, with a spinal cord that runs down to the base of the spine, forming the central nervous system.

Our bodies are essentially one long tube, starting with the mouth and nose and ending with the other end. Inside this tube is a mucosal lining, and it is composed of our digestive tract, airways, and brain. The brain is particularly interesting as it has to be crammed into the skull, so it looks like a cauliflower on the other end. If we were to splay it out, we’d find that it’s just one big tube. Similarly, our digestive tract and airways are also essentially one big tube, starting with the mouth and nose and then going down through our throat, stomach, and various intestines. Finally, the tube ends out the other end.

The tiny microvilli on the ends of cells act like velvety ends, allowing them to move and move things along and mucus mucosa. This mucosal lining sets the rate and quality of our digestion, as well as our immune system. Most infections in the environment have to get into our body somehow, and a lot of them go into our mouth and lodge in the mucosal lining of the mouth, where infection can start. People may have had the experience of feeling like something is irritating their throat, which can migrate up into a head cold or runny nose.

Sometimes it can start as a headache, but things that are inert can migrate down into the gut. We are constantly ingesting air, bacteria, and viruses which can bias the mucosal lining of the gut, stomach, and intestines to be more acidic or more basic. This allows certain bacteria to replicate, as they prefer a particular kind of bedding. The mucosal linings that they promote can make us feel better and more alert.

The microbiome isn’t good or bad – some of these little bugs that live in us do bad things to us, such as lowering our immunity and affecting us in negative ways. However, some of them make us feel better by changing the conditions of our gut environment and impacting neurotransmitters and neurons that live in the gut. This can affect dopamine and serotonin levels. There is now a vast world devoted to understanding what sources of food are good or not good for the gut microbiome.

Well that’s a good question and I think it’s something that people should experiment with and find out what works for them.

Supporting a healthy gut microbiome is good for mood, digestion, and immune system function. However, “more is not necessarily better” when it comes to taking probiotics and prebiotics. Studies have shown that if people take too much of certain probiotics like lactobacillus, they may experience brain fog, an inability to focus, and generally not feeling well. This is a bit controversial, but it’s best to experiment and find out what works for you. In a future episode, we will go deeper into the gut microbiome and gut-brain axis.

I get probiotics from Athletic Greens and I mentioned before that you can also get them from fermented foods like sauerkraut, pickles, kimchi, and natto. These are different sources from around the world and I’m fascinated by the way in which different cultures have all arrived at these foods that provide and support healthy microbiomes.

I have a colleague at Stanford, Justin Sonnenberg, and we have discussed how the ingestion of fermented foods is one of the best ways to support healthy levels of gut microbiota without exceeding the threshold that would cause brain fog.

Some people don’t like fermented foods, however, some people supplement it. So it isn’t a case of more is better. We know that.

Healthy gut microbiota have been shown to improve symptoms of certain psychiatric illnesses, such as particular features along the autism spectrum. This is likely due to the improved immune system function and the conditions in which neurons sense nutrients and increase levels of serotonin and dopamine. Eating small amounts of fermented foods is reported to improve mood, similar to the effects of EPA. There is a misconception that artificial sweeteners can disrupt the gut microbiome in detrimental ways, as shown in a study published in the journal “Nature”. This particular artificial sweetener, saccharin, can increase inflammatory cytokines and other negative health markers.

That study was widely discussed, but there were a few important things that were not mentioned. The study was specifically about saccharin, which is not the most common artificial sweetener used. Aspartame (NutraSweet), Sucralose, Stevia, and monk fruit are more typical. To my knowledge, the negative effects of these artificial sweeteners on the gut microbiome have been mainly restricted to saccharin. However, there is enough chemical similarity between saccharin and some other sweeteners that it should still be tested.

Saccharin has been shown in this study and several others to have a negative impact on the quality of the gut microbiome. Contrary to popular belief, artificial sweeteners do not necessarily kill the microbiome. Most people thought that saccharin was bad for the microbiome, leading to the misconception that all artificial sweeteners are bad for the microbiome.

The study published in Nature showed that the negative affects of saccharin on the microbiome could be blocked or eliminated by giving antibiotics. Saccharin and other artificial sweeteners disrupt the microbiome, making the environment within the gut more favorable to bacteria microbiota that are not good for the organism. This is an important distinction as it doesn’t kill the microbiome, but rather shifts it, which can be both good and bad. This leads to the hot button topic of people switching their diets to vegan, vegetarian, or keto diets. Keto diets don’t necessarily include the ingestion of meats, but can.

The ketogenic diet is interesting because when one shifts to it, there is a shift in the gut microbiome. Some people end up feeling better, while others may feel worse. Likewise, when transitioning to a plant-based diet, some people experience positive shifts in their mood and affect, while others may not. We know that the enrichment of fiber in these diets creates dramatic shifts in the gut microbiome, and some people feel better while others do not. Not everybody experiences positive effects from either diet, and I have previously discussed the incorrect marketing of keto as it relates to the cosmetic effects and potential sleep issues. Nevertheless, some people love keto and it works great for them.

Processed foods tend to create activity within the body and this surely has roots in the nervous system that lead to over-consumption of calories and weight gain, even some weight gain that couldn’t be explained by increased calories. Regardless of whether they come from animal sources or non-animal sources, processed foods are bad. This is probably not surprising given what we know about sugar sensing and other amino acid sensing cells in the gut.

When it comes to finding what’s right for you, it’s highly individual and has roots in genetic makeup as well as what people were raised on. The nervous system is set up by genetic program, but adapts early in life to one’s conditions. Some people’s microbiome and mucosa lining is improved by diets that are heavily meat based, while others do better on a plant-based diet.

The reason we have a nervous system is to move our body appropriately towards things that are good for us and away from things that are not. It was also designed to adapt. During the early life period, there is an incredible plasticity that allows us to change, meaning that some people may like certain foods and react to certain foods better than others due to the way their nervous system was wired. This enteric nervous system lines the gut and communicates with the brain.

We discussed many aspects of the gut-brain and body-brain axes, such as the sugar sensing neurons of the gut, the way the vagus is wired, and how omega-3 to omega-6 ratios tend to impact mood, with higher omega-3 to omega-6 ratios improving mood.

Lastly, we discussed the microbiome. We all have a microbiome, and understanding this is key.

You want a microbiome that is right for you, and that can be shifted and steered by ingesting certain categories of foods and not others. It is highly individual and there are ethical issues around animals and the planet which I am not qualified to talk about. When it comes to your health and your microbiome, it is clear that fermented foods should be ingested at least two servings per day. Supplementation at low levels can be beneficial, however, supplementation at high levels can create brain fog, even though some people say this result is controversial.

I’ve experienced this myself and the data looked to me pretty darn solid. So that’s one thing to think about as well. The other thing about the gut microbiome is that it’s highly contextual based on other things that you’re doing, such as exercise, social well-being, and connection. These things are also impacting the gut microbiome. My advice is to find the diet that’s right for you and that works for you in the context of the other ethical and lifestyle choices that are important to you.

A note about fasting: I have a colleague at Yale, who’s an expert in the gut microbiome, who told me something really interesting. When we fast, we actually digest certain components within our dietary tract.

Fasting, both intermittent and longer periods, depletes the gut microbiome. This may not be a bad thing, as replenishment often exceeds the previous levels. However, some people may not feel as good when they start eating again, which may be related to the depletion of the microbiome during long fasts. This is something to consider and discuss with a doctor, as fasting across the board may not be beneficial in all cases.

My colleague Alia Crum and her team at Stanford have done some remarkable experiments on mindset. In particular, two experiments stand out to me as they demonstrate how our beliefs can really impact the way our brain and body work together.

In the first experiment, two groups of individuals were given a milkshake and had some factors measured from their blood by an IV while they ingested the milkshake. The first group was told that the milkshake was high in calories and unhealthy, while the second group was told that the milkshake was low in calories and healthy.

The results showed that the group that was told the milkshake was healthy had a greater decrease in their blood glucose levels than the group that was told the milkshake was unhealthy. This demonstrates that our beliefs can have a powerful effect on our body’s response to food.

These results emphasize why it is important to have a gradual transition back to consuming nutrients after a fast. Our beliefs can have a profound impact on the way we respond to food mentally and physically.

The other group got a shake that they were told was a high calorie, unhealthy shake.

The group that was told they were drinking a low calorie, healthy shake had a decrease in their grehlin levels, while the group that was told they were drinking a high calorie, unhealthy shake had an increase in their grehlin levels. Researchers found that even though both groups were drinking the same shake, the perception of the shake affected the grehlin levels. This suggests that our attitude towards food can influence our hunger levels.

Two people were given a milkshake. One was told it was a decadent, high calorie shake, while the other was told it was a low calorie shake. In reality, it was the same shake given to both. Scientists measured the subjects’ blood for grehlin, and found that the high calorie shake had a much more robust effect on blunting grehlin and reducing grehlin levels. This speaks to the so-called top down mechanisms or modulation of our physiology, where beliefs or subjective feelings can impact physiology at the level of the periphery. This is yet another example where obsessive infatuation and love can have an effect on pain responses and pain thresholds.

Beliefs can extend beyond examples like this. Dr. Crum and her colleagues conducted an experiment where they divided hotel workers (housekeepers) into two groups. The first group watched a short film about how their work was important to help people feel comfortable in the hotel. The second group heard that the activity they were doing (cleaning and taking care of the hotel) was good for their health. The study was carefully controlled for health parameters and individual differences. Eight weeks later, the group that had been told that the activity was good for them showed lower blood pressure, had lost a significant amount of body fat, and reported enjoying their work far more than the other group. This demonstrates how mental bias can influence physiology.

This research illustrates the extent to which our beliefs about certain foods can impact their effects on our bodies. We cannot simply lie to ourselves and expect our bodies to respond in the way we want them to. Instead, the mind and body are in an interplay, where what we put into our bodies can affect our physiology, and our beliefs can magnify the effects of those substances. Additionally, our beliefs can sometimes even change the quality and direction of the impact. Finally, I want to thank everyone for their support of this podcast.

Since releasing at the beginning of the new year, we have received tremendous response and we are so grateful for it. I understand that there is a lot of information, like a college lecture. However, I strongly believe that if you learn the mechanisms and even hear them several times, they will become embedded into your understanding of the entire topic. I also try to provide tools that you can use immediately. Some might work for you and some might not. If they don’t work for you, discard them. If you are finding benefits from the information and tools and know others who could benefit from it, please pass along information about the podcast. Please subscribe to our YouTube channel, Apple and Spotify, if you haven’t already.

Please leave a review in the comment section here on YouTube. Also, if you feel we deserve it, please give us a five-star review on Apple. All those things really help us.

In addition, if you’d like to support the podcast further, we’ve set up a Patreon account. It’s patreon.com/andrewhuberman and it allows you to support the podcast at a variety of levels. We have the 5-HTP serotonin for $5 a month, the Costello for $10 a month in honor of Costello, et cetera. You don’t have to, but if you’d like to, that would be terrific.

In addition, please check out our sponsors that we’ve mentioned at the beginning of the podcast. That’s one of the best ways to help support us.

We believe in all the products we support and our sponsors, which is why we have partnered with Thorne, T-H-O-R-N-E. Thorne uses the highest levels of stringency and rigor in their products, which is why they are used by the Mayo Clinic and major sports teams. If you want to know what supplements I take, you can go to thorne.com/u/huberman and get 20% off any of the supplements and products Thorne makes.

In today’s episode, we discussed the brain-body relationship and the actionable items you can approach if you want to explore this aspect of your biology and psychology further. Last, but certainly not least, I want to thank everybody for their time and attention and thank you for your interest in science.