How Foods & Nutrients Control Our Moods

00:00:00.000 | - Welcome to Huberman Lab Essentials,

00:00:02.320 | where we revisit past episodes

00:00:04.400 | for the most potent and actionable science-based tools

00:00:07.560 | for mental health, physical health, and performance.

00:00:10.320 | My name is Andrew Huberman,

00:00:13.360 | and I'm a professor of neurobiology and ophthalmology

00:00:16.400 | at Stanford School of Medicine.

00:00:18.420 | This podcast is separate

00:00:19.600 | from my teaching and research roles at Stanford.

00:00:21.760 | Today, we're talking all about emotions.

00:00:24.520 | Emotions are central to our entire experience of life.

00:00:28.200 | Whether or not we're happy or sad or depressed or angry

00:00:32.240 | is our life experience.

00:00:34.440 | And yet, I think with all the importance

00:00:37.000 | that we've placed on emotions,

00:00:38.360 | very few people actually understand

00:00:39.720 | how emotions arise in our brain and body.

00:00:42.400 | And I mentioned brain and body because as you'll see today,

00:00:45.840 | emotions really capture the brain-body relationship.

00:00:49.500 | We cannot say that emotions arise

00:00:51.520 | just from what happens in our head.

00:00:53.320 | The other thing about emotions

00:00:54.520 | is that there's no real agreement

00:00:56.640 | as to what's a good emotion or a bad emotion.

00:00:59.800 | Today, we're going to talk about the biology

00:01:01.600 | of the chemicals and pathways that give rise to emotions

00:01:04.720 | in the context of food and nutrition.

00:01:07.680 | The discussion around emotions has a long and rich history,

00:01:11.280 | going back to Darwin and even long before Darwin.

00:01:14.440 | You know, this is a conversation that philosophers

00:01:16.680 | and scientists have been having for hundreds,

00:01:19.160 | if not thousands of years.

00:01:21.360 | You know, the idea that Darwin put forth

00:01:24.000 | and that was really attractive for about the last 100 years

00:01:27.100 | was that emotions are universal

00:01:29.680 | and that some of the facial expressions

00:01:31.200 | around emotion are universal.

00:01:32.880 | And other people have, you know, capitalized on that idea.

00:01:36.560 | And to some extent, it's true.

00:01:38.200 | I mean, I think that the two most robust examples of that

00:01:42.960 | would be when we see something or we smell something

00:01:47.440 | or we taste something that we like,

00:01:49.280 | there does tend to be a postural leaning in.

00:01:52.660 | We tend to inhale air at that time.

00:01:55.120 | We tend to bring in more

00:01:56.720 | of whatever chemical substance is there.

00:01:58.440 | So we tend to do these mmms and, you know,

00:02:00.560 | and kind of lean in closer to things

00:02:02.180 | that are attractive to us.

00:02:03.800 | And when we see and experience things that we don't like,

00:02:08.320 | sometimes it's a mild aversion.

00:02:09.900 | We just kind of lean back or look away.

00:02:11.640 | Other times, it's an intense aversion of disgust.

00:02:14.740 | And we tend to cringe our face.

00:02:16.380 | We tend to avoid inhaling any of the chemicals.

00:02:18.740 | This probably has roots in ancient biological mechanisms

00:02:22.880 | that are to prevent us from ingesting things

00:02:25.580 | that are bad for us,

00:02:26.600 | chemical compounds and tastes that might be poisonous.

00:02:29.480 | So much of the foundation of any discussion about emotion

00:02:33.780 | has to center around this kind of push-pull

00:02:35.960 | of attraction to things or aversion from things.

00:02:39.720 | Now, that's a very basic way of thinking about emotions.

00:02:42.600 | But if you think about it,

00:02:43.760 | it works for a lot of different circumstances.

00:02:45.960 | And in the brain,

00:02:47.120 | everywhere from the deep circuits of the brain

00:02:49.320 | to the more kind of what we call higher order

00:02:51.480 | revolve centers of the brain,

00:02:53.080 | we have this push-pull thing.

00:02:55.280 | We're either, in a previous episode, I talked about go,

00:02:57.880 | the circuits that allow you to emphasize action.

00:03:01.480 | And then no-go circuits,

00:03:03.160 | the circuits in the basal ganglia

00:03:04.540 | that allow you to de-emphasize action and prevent action.

00:03:08.320 | And so we can break down the discussion about emotions

00:03:11.680 | into these simpler versions of themselves.

00:03:14.660 | But at the core of that, of attraction or aversion

00:03:18.680 | is an important theme that you might realize already,

00:03:22.040 | but most people tend to overlook,

00:03:23.920 | which is that there's an action there.

00:03:26.320 | You're either moving forward

00:03:27.840 | or you're moving away from something.

00:03:29.700 | The brain has a body so that the organism can move.

00:03:33.660 | And the body has a brain so that the organism, you,

00:03:37.400 | can move toward or away from things

00:03:39.200 | that you deem to be good or bad for you.

00:03:41.600 | So there are circuits in the brain for aversion

00:03:44.240 | and for attraction toward things.

00:03:46.100 | And the body is governing a lot of that.

00:03:48.700 | And so immediately in this conversation,

00:03:50.660 | I want to raise an important point,

00:03:52.820 | which is about a nerve pathway

00:03:55.100 | that many, many people have heard of

00:03:57.220 | that gets discussed all the time.

00:03:58.700 | And that is one of the most kind of oversold

00:04:01.820 | for the wrong reasons and undersold, unfortunately,

00:04:04.940 | for its real power, which is the vagus nerve.

00:04:08.340 | So the vagus nerve is one, not the only,

00:04:12.020 | but one way in which our brain and body are connected

00:04:14.920 | and regulates our emotional states.

00:04:18.400 | So what is the vagus nerve?

00:04:19.800 | Vagus is the 10th cranial nerve,

00:04:21.640 | which basically means that the neurons,

00:04:23.840 | the control center of each of those neurons in the vagus,

00:04:27.460 | lives just kind of near the neck, right?

00:04:30.880 | And a branch of the vagus goes into the brain.

00:04:33.520 | The other branch goes into the periphery,

00:04:35.560 | but not just the gut.

00:04:37.260 | It goes into the stomach, the intestines, the heart,

00:04:40.040 | the lungs, and the immune system.

00:04:42.040 | So the way to think about the vagus

00:04:44.720 | is the same way I would think about the eyes.

00:04:46.800 | The eyes are looking at colors, they're looking at motion,

00:04:49.760 | they're looking how bright it is.

00:04:51.120 | And each one of those things, those features,

00:04:53.960 | is telling the brain something different

00:04:55.320 | so the brain can decide when to be awake or asleep,

00:04:57.660 | whether or not it's looking at somebody

00:04:59.360 | attractive or unattractive.

00:05:01.640 | The vagus nerve is also analyzing many features

00:05:04.820 | within the body and informing the brain

00:05:07.280 | of how to feel about that and what to do.

00:05:10.840 | So a really good example that I think is an exciting one

00:05:14.200 | is as it relates to sugar.

00:05:16.900 | So we all know that sweet things generally taste good.

00:05:20.440 | So that makes sense, right?

00:05:21.520 | You eat something, it tastes sweet, you want more of it.

00:05:24.160 | Well, it turns out that it's much more interesting than that.

00:05:27.560 | When you eat something sweet, within your stomach,

00:05:31.680 | you have cells, neurons, that sense the presence

00:05:35.560 | of sugary foods, independent of their taste,

00:05:38.960 | and signal to the brain, so those sensors, those neurons,

00:05:43.080 | send information up the vagus to your brain,

00:05:45.880 | goes through a series of stations,

00:05:47.440 | and then you release dopamine, this molecule

00:05:50.640 | that makes you want more of whatever it is

00:05:53.560 | that you just ingested.

00:05:55.120 | In fact, this pathway is so powerful

00:05:58.160 | that they've done experiments where they completely numb

00:06:01.360 | all the taste and feeling in somebody's mouth.

00:06:04.380 | They're blindfolded, so they don't know

00:06:05.640 | what they're eating, and they're eating a food

00:06:07.560 | that's either sugary or not sugary.

00:06:09.720 | And what they find is that even though

00:06:11.360 | people can't taste the sugary food,

00:06:13.560 | they crave more of the food that contains sugar

00:06:17.440 | because of the sensors in the gut that sense sugar.

00:06:21.240 | And what it tells us is that we have circuits in our body

00:06:24.260 | that are driving us towards certain behaviors

00:06:26.740 | and making us feel good, even though we can't perceive them.

00:06:30.640 | Now, for those of you that are really interested

00:06:32.360 | in gut intuition and kind of gut feelings,

00:06:35.240 | this is a gut feeling,

00:06:36.600 | except this is a chemical gut feeling.

00:06:38.720 | This is a particular set of neurons

00:06:41.480 | detecting that something in your body

00:06:44.260 | has a particular feature, in this case,

00:06:46.060 | the presence of sugars, and sending information

00:06:48.720 | to the brain essentially to control your behavior.

00:06:52.440 | And I find this remarkable.

00:06:54.400 | I mean, this should completely reframe the way

00:06:56.360 | that we think about the so-called hidden sugars in foods.

00:07:00.200 | What this means is that even if a food is very savory,

00:07:02.960 | like a piece of pizza or a piece of bread,

00:07:05.880 | or even like a salad dressing,

00:07:08.680 | if there's sugar snuck into that and you can't taste it,

00:07:12.360 | you will still crave more of that thing

00:07:15.520 | without knowing that you crave it because it has sugar.

00:07:18.720 | So I find this to be a fascinating aspect of our biology.

00:07:21.600 | A lot of how we feel while we eat and after we eat

00:07:26.860 | is because of this vagus sensing of what's in our gut.

00:07:31.180 | It's sending information all the time.

00:07:33.640 | Is there sugar?

00:07:35.400 | Are there fats?

00:07:36.940 | Are there contaminants?

00:07:38.980 | There are a lot of information,

00:07:40.380 | these so-called parallel pathways

00:07:41.700 | that are going up into our brain

00:07:42.940 | that regulate whether or not we want to eat

00:07:44.660 | more of something or not.

00:07:46.140 | And there are accelerators,

00:07:47.580 | things that make us want to eat more,

00:07:49.500 | like sugar and fats, because those are nutrient dense

00:07:53.140 | and they helps generally, at least in the short term,

00:07:55.380 | support the survival of animals, but also amino acids.

00:07:59.940 | And this is very important.

00:08:02.260 | There are a lot of data,

00:08:04.260 | but much of what comes from the data on what people eat

00:08:09.260 | and how much they eat is from a subconscious detection

00:08:13.220 | of how many amino acids and what the array,

00:08:17.900 | meaning the constellation of amino acids is in a given food.

00:08:21.380 | And it's fair to say that the sum total of these studies,

00:08:25.300 | point in a direction where people will basically eat,

00:08:28.880 | not until their stomach is full,

00:08:31.540 | but until the brain perceives

00:08:35.260 | that they have adequate intake of amino acids.

00:08:38.100 | It's amino acids, of course,

00:08:39.500 | are important because they are the building blocks of sure,

00:08:42.540 | muscle and the other things in our body that need repair.

00:08:46.240 | But what most people don't realize is that amino acids

00:08:50.220 | are what the neurochemicals in the brain are made from.

00:08:54.540 | Now, this is vitally important, okay?

00:08:57.020 | So we've heard dopamine is this molecule

00:08:59.820 | that makes you feel good.

00:09:00.780 | Dopamine release is caused by surprise, excitement,

00:09:04.000 | events that you're looking forward to

00:09:05.340 | and that turn out well.

00:09:07.140 | It is inhibited by events you're looking forward to

00:09:09.660 | that don't work out.

00:09:11.000 | It's called reward prediction error.

00:09:13.180 | Your expectation of something releases dopamine

00:09:16.580 | and the actual event releases dopamine.

00:09:19.940 | And if the event related dopamine

00:09:23.420 | does not exceed the expectation or at least match it,

00:09:26.660 | there's a much higher tendency

00:09:28.180 | that you won't pursue that thing again.

00:09:30.940 | Dopamine is what's going to lead us

00:09:33.940 | to want to eat more of something

00:09:35.700 | or to not want more of something

00:09:37.380 | because dopamine really is about craving.

00:09:40.360 | It's about motivation and it's about desire.

00:09:43.340 | And as I mentioned,

00:09:44.400 | these amino acid sensors in our gut

00:09:46.660 | are detecting how many amino acids,

00:09:49.000 | but they're also detecting which amino acids.

00:09:51.520 | And there's a particular amino acid called L-tyrosine

00:09:54.820 | which comes from food.

00:09:56.560 | It is in meats, it is in nuts,

00:09:58.360 | it is also in some plant-based foods.

00:10:00.900 | L-tyrosine is the precursor to a couple other molecules

00:10:05.900 | like L-DOPA, et cetera, that make dopamine.

00:10:09.440 | However, the dopamine neurons that give rise

00:10:12.740 | to these feelings of good or wanting more

00:10:15.920 | or desire and motivation, those reside in the brain.

00:10:19.180 | So we don't want to get too confused.

00:10:20.460 | We want to respect and honor the power of the gut

00:10:23.240 | and this vagal pathway,

00:10:24.680 | but it's really neurons within your brain

00:10:26.300 | that drive the pursuit and decision-making.

00:10:29.200 | So what does this mean?

00:10:30.160 | Well, some people make too little dopamine.

00:10:34.000 | Some people make so little dopamine

00:10:35.480 | that they need prescription dopamine.

00:10:37.840 | They need L-DOPA.

00:10:38.800 | People with Parkinson's take L-DOPA

00:10:40.920 | and other compounds to increase dopamine

00:10:42.960 | because Parkinson's is associated

00:10:45.440 | with deficits in movement.

00:10:47.680 | Parkinson's is a depression.

00:10:51.160 | It's a blunting of motivation and mood and affect,

00:10:54.280 | and it's a tremor.

00:10:55.160 | And then eventually in severe conditions,

00:10:56.840 | it's challenges in speaking and walking.

00:10:58.960 | So some famous examples would be Muhammad Ali,

00:11:02.040 | Michael J. Fox, the great boxing trainer, Freddie Roach.

00:11:06.920 | Like these people have Parkinson's

00:11:08.880 | and they, at least later in their life,

00:11:10.800 | had challenges speaking.

00:11:12.580 | Now, some people immediately ask,

00:11:14.240 | well, should I supplement L-tyrosine?

00:11:16.120 | It does increase kind of mood and elevation and alertness.

00:11:20.080 | It is over the counter.

00:11:21.200 | You have to check with your doctor.

00:11:22.460 | I'm not responsible for your healthcare,

00:11:23.960 | and I'm not a doctor.

00:11:25.480 | Whether or not it's safe for you.

00:11:26.520 | People with preexisting hyper-dopaminergic conditions

00:11:29.440 | like mania should probably not take L-tyrosine.

00:11:33.360 | The other thing about taking L-tyrosine

00:11:34.880 | is there is a crash, okay?

00:11:36.600 | It's not a massive crash if you take it

00:11:38.320 | at appropriate doses and it's right for you,

00:11:40.740 | but it can produce a crash and a lethargy

00:11:43.560 | and a kind of brain fog after the next day or so.

00:11:47.000 | And so L-tyrosine, however, can be ingested through foods

00:11:52.000 | or through supplementation to increase dopamine levels.

00:11:54.400 | That's well-known.

00:11:55.240 | Taking chronically, however,

00:11:56.740 | it can disrupt those dopamine pathways.

00:11:58.940 | Let's just kind of take stock of where we're at.

00:12:00.600 | We have a brain-body connection.

00:12:02.120 | There are many of them,

00:12:03.160 | but one of the main ones is the vagus nerve.

00:12:05.120 | The vagus collects information about a lot of things,

00:12:07.560 | breathing, heart rate,

00:12:09.240 | stuff that's happening in the gut, et cetera.

00:12:11.560 | And gut, by the way, includes the stomach

00:12:13.040 | and the intestines,

00:12:14.000 | sends that information up to the brain.

00:12:16.280 | The brain is using that information

00:12:17.960 | to decide one of two things,

00:12:19.680 | move toward something or move away.

00:12:22.200 | It can also pause,

00:12:23.200 | but essentially pausing is not moving toward.

00:12:26.000 | So that's the dopamine pathway.

00:12:28.440 | And foods rich in L-tyrosine

00:12:30.160 | generally give us an elevated mood

00:12:32.080 | and make us want to do more of whatever it is

00:12:34.200 | that we happen to be doing, as well as other things.

00:12:36.480 | Motivation generalizes to other things.

00:12:38.440 | It's not unique to just ingesting foods.

00:12:40.800 | But foods that give us a big pulse of dopamine

00:12:43.600 | will make us crave more of that food.

00:12:46.480 | It will make us crave more of the activity

00:12:48.800 | that led to the ingestion of that food.

00:12:51.480 | And as I mentioned earlier,

00:12:52.520 | a lot of that is happening at a subconscious level

00:12:55.420 | that you're not even aware of.

00:12:56.960 | So the other neuromodulator that's really interesting

00:12:59.360 | in the context of the vagus is serotonin.

00:13:02.440 | Serotonin, just to remind you, is a neuromodulator.

00:13:05.840 | Therefore, it creates a bias in which neural circuits,

00:13:09.300 | which neurons in the brain and body are going to be active,

00:13:12.320 | and it makes it less likely

00:13:13.600 | that other ones are going to be active.

00:13:15.920 | And serotonin, when it's elevated,

00:13:17.560 | tends to make us feel really comfortable

00:13:19.840 | and kind of blissed out wherever we are.

00:13:22.720 | And that contrasts with dopamine and epinephrine,

00:13:26.240 | which mainly put us in pursuit of things.

00:13:28.920 | Motivation is pursuit.

00:13:30.480 | The conversation around the brain-body relationship

00:13:33.060 | and mood in serotonin for many years was,

00:13:35.000 | well, you eat a big meal, the gut is distended,

00:13:37.560 | you've got all the nutrients you need,

00:13:38.860 | you rest and digest, and serotonin is released.

00:13:42.400 | That's sort of true, but there's a lot more going on

00:13:46.440 | and a lot more that's interesting and actionable

00:13:48.560 | that's going on.

00:13:49.640 | First of all, some of you, but perhaps not all,

00:13:52.280 | have heard that more than 90% of the serotonin

00:13:55.920 | that we make is in our gut.

00:13:57.600 | And indeed, we have a lot of serotonin in our gut.

00:14:00.680 | But here's the deal.

00:14:01.680 | Most of the serotonin that impacts our mood

00:14:05.280 | and our mental state is not in our gut.

00:14:08.360 | Most of it is in the neurons of the brain

00:14:10.460 | in an area called the raphe nucleus of the brain.

00:14:12.800 | There are a few other locations too.

00:14:15.240 | You can't have a discussion about serotonin

00:14:17.440 | without having a discussion about antidepressants

00:14:19.560 | because during the late '80s and early '90s,

00:14:22.560 | there was this explosion in the number of prescription drugs

00:14:25.840 | that were released.

00:14:26.680 | Things like, first one and most famous one is Prozac,

00:14:29.240 | Zoloft, Paxil, a number of other ones

00:14:31.680 | that are so-called SSRI,

00:14:33.400 | selective serotonin reuptake inhibitors.

00:14:36.520 | Basically, those drugs work by preventing

00:14:39.960 | the gobbling up of serotonin

00:14:43.960 | or reuptake of serotonin into neurons

00:14:46.800 | after it's been released,

00:14:47.760 | which leads to more serotonin overall,

00:14:49.960 | which means to elevate serotonin.

00:14:51.480 | And indeed, those drugs were and can be very useful

00:14:55.600 | for certain people to feel better in cases of depression

00:14:59.080 | and some other clinical disorders as well.

00:15:01.640 | Not everyone responds well to them,

00:15:03.480 | as I'm sure you've all heard,

00:15:05.160 | and their side effect profile

00:15:07.880 | has effects like blunting affect.

00:15:10.760 | It can make people feel kind of flat, kind of meh.

00:15:13.040 | Many people adjust their serotonin

00:15:14.800 | by just eating more food,

00:15:16.680 | and carbohydrate-rich foods will increase serotonin.

00:15:20.560 | I eat a relatively high-protein and moderate-fat,

00:15:25.200 | zero-carb or low-carb meal at lunch

00:15:28.480 | and in the afternoon to stay alert

00:15:30.240 | because those foods tend to favor dopamine production,

00:15:33.520 | acetylcholine production, epinephrine production,

00:15:35.600 | and alertness.

00:15:36.720 | My mood is generally pretty good most of the time.

00:15:40.240 | And then as evening comes around

00:15:42.020 | and I'm concerned about sleep and a good night's sleep,

00:15:45.500 | not concerned in an anxious way,

00:15:46.760 | but I want to get a good night's sleep,

00:15:48.400 | I will ingest foods that promote serotonin release

00:15:51.380 | because they contain a lot of tryptophan.

00:15:53.700 | So as you're seeing,

00:15:54.540 | this isn't really a discussion about nutrition per se.

00:15:56.680 | This is a discussion about food which contains amino acids,

00:16:00.040 | amino acids being the precursors to neuromodulators,

00:16:02.720 | and neuromodulators having a profound effect

00:16:05.600 | on your overall state of alertness or calmness,

00:16:08.640 | happiness, sadness, and wellbeing.

00:16:10.800 | So now you understand the relationship, I hope,

00:16:14.960 | between foods and dopamine, foods and serotonin,

00:16:19.480 | and that they're both being communicated to the brain

00:16:21.680 | via the vagus, right?

00:16:23.000 | So let's talk a little bit more about things

00:16:25.160 | that we ingest in our body

00:16:26.600 | and then allow our body to inform our brain

00:16:29.320 | to shift our mood.

00:16:30.320 | But I don't think most people know this simple fact,

00:16:33.680 | which is that the omega-3 to omega-6 fatty acid ratio

00:16:38.680 | has a profound effect on depression.

00:16:41.700 | First of all, in an experiment done in animals,

00:16:45.000 | they found there's a model of learned helplessness

00:16:47.200 | in animals.

00:16:48.020 | It's not very kind to the animals,

00:16:49.080 | but they put rats or mice in a jar,

00:16:50.920 | they let them swim,

00:16:52.400 | and they'll swim, swim, swim to try and save their life,

00:16:54.680 | and eventually they give up.

00:16:55.800 | It's a learned helplessness.

00:16:56.720 | They don't let them drown, they take them out.

00:16:59.880 | Adjusting the omega-3, omega-6 ratio

00:17:02.400 | so that the omega-3s are higher

00:17:04.880 | led to less learned helplessness,

00:17:07.160 | meaning these animals would swim longer.

00:17:09.160 | But that same study was essentially done in humans.

00:17:12.940 | What they did is they took people

00:17:16.120 | who were clinically depressed, major depression, okay?

00:17:19.040 | Major depression is severe maladaptive state,

00:17:23.000 | meaning it inhibits job, relationships, appetite,

00:17:26.340 | all sorts of negative health effects.

00:17:29.080 | And they did a comparison of 1,000 milligrams a day of EPA.

00:17:34.080 | So EPA is one of the elements

00:17:37.320 | that contains high levels of omega-3s

00:17:39.360 | that's in things like fish oil,

00:17:41.040 | but it wasn't 1,000 milligrams of fish oil,

00:17:44.480 | it was 1,000 milligrams of EPA.

00:17:47.720 | Compared that to 20 milligrams of fluoxetine,

00:17:51.200 | which is Prozac,

00:17:53.180 | they found that they were equally effective

00:17:56.460 | in reducing depressive symptoms.

00:17:58.320 | And what was really interesting in addition to that

00:18:01.520 | is that the combination of 1,000 milligrams of EPA

00:18:05.280 | and fluoxetine had a synergistic effect

00:18:07.440 | in lowering depressive symptoms.

00:18:09.080 | And now there are lots of studies.

00:18:11.420 | If you go into PubMed and you were to put EPA

00:18:14.800 | or fish oil and depression,

00:18:16.560 | you would find that there were a number

00:18:18.320 | of really impressive results

00:18:19.960 | showing that it's at least as effective

00:18:22.000 | as certain SSRIs, antidepressants, at these dosages.

00:18:26.920 | And it can amplify or improve the effect of low dosages

00:18:30.160 | of some of these SSRIs.

00:18:32.000 | You can discuss it with your doctor and family

00:18:34.000 | and make the choices that are right for you.

00:18:36.080 | Now, of course, I really want to emphasize something,

00:18:38.840 | which is that no one compound

00:18:42.360 | or nutrient or supplement or drug

00:18:45.280 | or behavior for that matter

00:18:47.160 | is going to be the be-all end-all

00:18:49.980 | of shifting out of depression

00:18:52.420 | or improving one's mood or improving sleep.

00:18:55.400 | You cannot expect to take a compound,

00:18:58.280 | regardless of source or potency,

00:19:00.660 | and have it completely shift your experience of life

00:19:03.780 | without having to continue to engage

00:19:05.680 | in the proper behaviors, all the things we know,

00:19:07.900 | proper sleep, exercise, social connection, food, et cetera.

00:19:11.200 | Okay, so now let's turn to another aspect

00:19:14.940 | of the gut-brain relationship that will surprise you,

00:19:19.840 | in some cases might shock you,

00:19:21.820 | and that has some really cool and actionable biology.

00:19:25.500 | And that's the gut microbiome, probiotics, and prebiotics.

00:19:30.500 | So what's the deal with the gut microbiome

00:19:33.500 | and the gut-brain axis?

00:19:35.540 | Today, we've actually been talking a lot already

00:19:37.940 | about the gut-brain axis

00:19:39.980 | that has nothing to do with microbiomes.

00:19:42.100 | We've been talking about this vagus nerve

00:19:44.420 | that connects, providing sensory information

00:19:48.620 | from the body to the brain,

00:19:50.060 | and then the brain also sends, in the same nerve,

00:19:53.800 | motor information to control the motility, the gut,

00:19:56.980 | the heart rate, how fast we breathe,

00:19:59.120 | and deployment of immune stuff.

00:20:02.620 | But oftentimes, when we hear

00:20:04.600 | about the gut-brain axis these days,

00:20:07.600 | it's a discussion about the gut microbiome.

00:20:10.940 | I'm very happy there's so much discussion

00:20:12.900 | about the gut microbiome.

00:20:14.580 | I am somewhat dismayed and concerned

00:20:17.060 | that most of what I hear out there

00:20:18.940 | is either false or partially false.

00:20:22.220 | So we're going to clear up some of the misconceptions,

00:20:25.380 | first by understanding the biology,

00:20:26.900 | and then we're going to talk

00:20:27.720 | about some of the actionable items.

00:20:29.380 | It is true that we have a lot

00:20:33.660 | of these little microorganisms living in our gut.

00:20:38.660 | They're not there because they want to help us.

00:20:42.180 | They don't have brains.

00:20:43.440 | They are adaptive, however.

00:20:45.220 | They try and find and create environments

00:20:49.340 | that make it easier for them to proliferate.

00:20:51.940 | So they don't care about you and me,

00:20:54.140 | but they are perfectly willing to exploit you and me

00:20:57.440 | in order to make more of themselves.

00:21:00.020 | The microbiota that live in us

00:21:03.100 | vary along the length of our digestive tract.

00:21:06.240 | So we are one long tube for digestion,

00:21:08.540 | and inside of that tube is a mucosal lining.

00:21:12.420 | And the conditions of that mucosal lining

00:21:15.740 | set a number of different things.

00:21:17.740 | It sets the rate of our digestion

00:21:19.940 | and the quality of our digestion.

00:21:22.020 | It sets, for instance, our immune system.

00:21:24.260 | We're ingesting things all the time.

00:21:25.860 | Think about air, bacteria, viruses,

00:21:28.660 | they're making their way into our gut.

00:21:30.580 | And some of those bacteria live in the gut,

00:21:33.060 | and some of those bacteria

00:21:35.180 | bias the mucosal lining in the gut,

00:21:39.220 | stomach and intestines,

00:21:40.920 | to be more acidic or more basic

00:21:45.060 | so that they can make more of themselves,

00:21:47.260 | so they can replicate.

00:21:48.140 | Now, some of those mucosal linings that they promote

00:21:52.380 | make us feel better.

00:21:53.620 | They make us feel more alert.

00:21:54.820 | They bolster our immune system,

00:21:56.180 | and others make us feel worse.

00:21:57.940 | So first rule,

00:22:00.880 | the microbiome isn't good or bad.

00:22:03.740 | Some of these little bugs that live in us

00:22:05.860 | do bad things to us.

00:22:07.020 | They make us feel worse.

00:22:08.540 | They lower our immunity.

00:22:09.940 | They affect us in negative ways.

00:22:12.260 | Some of them make us feel better.

00:22:13.820 | And they do that mainly by changing the conditions

00:22:17.380 | of our gut environment.

00:22:20.100 | In addition to that,

00:22:21.300 | they do impact the neurotransmitters

00:22:26.140 | and the neurons that live in the gut

00:22:28.780 | and that signal up to the brain

00:22:30.380 | to impact things like dopamine and serotonin

00:22:32.380 | that we've been talking about previously.

00:22:34.700 | So there's a vast world now

00:22:38.620 | devoted to trying to understand what sources of food,

00:22:41.940 | what kinds of foods are good or not good

00:22:44.700 | for the gut microbiome.

00:22:46.060 | Here's a few things that I think you might find surprising.

00:22:50.700 | First of all,

00:22:51.660 | supporting a healthy gut microbiome is good for mood,

00:22:55.760 | great for digestion,

00:22:57.220 | and great for immune system function.

00:23:00.020 | However, that does not mean maxing out

00:23:04.740 | or taking the most probiotic and prebiotic

00:23:07.760 | that you can possibly manage.

00:23:09.660 | As I mentioned many times before,

00:23:11.220 | I do believe in probiotics.

00:23:12.900 | I take probiotics.

00:23:14.260 | But there are studies that show

00:23:15.420 | that if you take lots and lots of certain probiotics

00:23:18.800 | like lactobacillus and you really ramp up the levels more,

00:23:22.220 | it is not a case of more is better.

00:23:24.500 | There are things like brain fog that can come from that.

00:23:28.620 | Brain fog is just this inability to focus.

00:23:30.860 | People feel really not well generally.

00:23:33.400 | Some of those studies are a little bit controversial,

00:23:35.040 | but I think it's fair to say

00:23:36.100 | that if people really increase the amount of probiotic

00:23:40.380 | that they're taking beyond a certain amount,

00:23:43.940 | then they start feeling foggy in the mind.

00:23:46.900 | The ingestion of fermented foods

00:23:49.260 | is one of the best ways to support healthy levels

00:23:51.680 | of gut microbiota without exceeding the threshold

00:23:55.860 | that would cause things like brain fog.

00:23:58.940 | So much so that some people report

00:24:00.660 | that when they start eating small bits,

00:24:03.220 | 'cause it doesn't require a lot of fermented foods,

00:24:05.420 | that their overall mood is better,

00:24:06.860 | not unlike the effects of EPA,

00:24:08.340 | although I don't think it's been looked at directly

00:24:11.020 | in the context of clinical depression yet.

00:24:13.460 | There are some things that you can do

00:24:15.600 | to really damage your gut microbiome.

00:24:17.940 | And this is where there's a huge misconception

00:24:20.260 | that I want to clear up.

00:24:21.900 | There was a study that showed that artificial sweeteners,

00:24:24.900 | but a particular artificial sweetener, which was saccharin,

00:24:28.440 | can disrupt the gut microbiome

00:24:31.660 | in ways that is detrimental

00:24:33.060 | to a number of different health markers,

00:24:35.100 | increasing inflammatory cytokines

00:24:37.500 | and all the other bad things that happen

00:24:39.700 | when the gut microbiome is thrown off kilter.

00:24:43.980 | Saccharin is not the most typical artificial sweetener

00:24:48.140 | that's used.

00:24:48.980 | The most typical artificial sweeteners that are used

00:24:51.380 | are things like aspartame, so-called NutraSweet,

00:24:54.940 | or sucralose, or these days Stevia.

00:24:57.420 | To my knowledge, the negative effects

00:25:00.980 | of artificial sweeteners on the gut microbiome

00:25:05.100 | were restricted to saccharin.

00:25:07.380 | So what happens is certain artificial sweeteners,

00:25:10.020 | in particular saccharin, disrupt the microbiome

00:25:14.020 | and make the environment within the gut,

00:25:16.880 | that mucosal lining, more favorable to bacteria microbiota

00:25:21.880 | that are not good for the organism.

00:25:25.820 | Okay, this is an important distinction.

00:25:28.020 | It's not just that a language thing where people say,

00:25:30.500 | "Oh, you know, it kills the microbiome."

00:25:32.660 | It doesn't kill the microbiome, it shifts the microbiome.

00:25:36.060 | And shifts in the microbiome can be good or they can be bad.

00:25:39.100 | And that takes us to another topic

00:25:41.220 | that's a bit of a hot button topic,

00:25:42.640 | but I'm willing to go there

00:25:43.540 | 'cause I think it deserves conversation,

00:25:45.840 | which is nowadays there are many examples out there

00:25:49.380 | where people have switched from a kind of standard diet

00:25:52.380 | or even a vegetarian diet or vegan diet to a keto diet.

00:25:57.380 | Now, keto doesn't necessarily have to mean

00:25:59.140 | the ingestion of meats, but it can.

00:26:02.140 | And they experience positive effects for themselves.

00:26:04.860 | But the ketogenic diet is interesting

00:26:07.820 | because when one shifts to the ketogenic diet,

00:26:10.340 | there is a shift in the gut microbiome

00:26:12.180 | and some people end up feeling better.

00:26:14.040 | Some people end up feeling worse.

00:26:16.260 | Likewise, some people go from ingesting animal products,

00:26:21.740 | including meat or they're vegetarian and they go to vegan,

00:26:25.360 | and they experience positive shifts in mood and affect.

00:26:29.980 | So the point of all this is that

00:26:32.300 | when I say you have to find what's right for you,

00:26:34.380 | that's not a throwaway statement.

00:26:36.340 | Some people's microbiome and the mucosal lining

00:26:40.380 | of their throat, of their gut, of their nose,

00:26:42.860 | everything is improved by diets that are heavily meat-based

00:26:47.220 | and don't have many plants.

00:26:48.340 | Other people do much better on a plant-based diet

00:26:51.140 | without many meat products or animal products.

00:26:53.340 | It's highly individual.

00:26:54.740 | And this probably has roots in genetic makeup.

00:26:57.520 | This probably has roots in what people were raised on.

00:27:01.320 | Because remember, the nervous system, of course,

00:27:03.760 | is set up by your genes, your genetic program,

00:27:06.440 | but your nervous system,

00:27:07.600 | it adapts early in life to your conditions.

00:27:11.140 | That's what it's for.

00:27:12.000 | The reason you have a nervous system

00:27:13.280 | is to move your body appropriately

00:27:15.480 | towards things that are good for you

00:27:16.680 | and away from things that are not.

00:27:17.940 | But also it was designed to adapt.

00:27:20.240 | So that, yes, indeed, some people may like certain foods

00:27:22.600 | and react to certain foods better than others

00:27:24.820 | because of the way that their nervous system was wired,

00:27:27.940 | this enteric, as it's called, nervous system

00:27:30.140 | that lines the gut and that communicates with the brain.

00:27:32.980 | So most of what I've talked about today

00:27:34.740 | is black and white.

00:27:37.220 | These are things that are present in all of us,

00:27:38.820 | the sugar-sensing neurons of the gut,

00:27:40.220 | the way the vagus is wired,

00:27:41.920 | the fact that omega-3, omega-6 tend to improve,

00:27:44.740 | the ratios tend to impact mood

00:27:46.660 | with high omega-3, omega-6 ratios improving mood.

00:27:49.900 | We talked about all sorts of things

00:27:52.260 | in the gut-brain and body-brain axis,

00:27:54.760 | but when it comes to the microbiome,

00:27:57.000 | the key thing is that we all have a microbiome.

00:27:59.400 | You want a microbiome,

00:28:00.880 | but you want to promote the microbiome

00:28:03.360 | that is right for you.

00:28:04.960 | And that can be shifted and steered

00:28:07.760 | by ingesting certain categories of foods and not others.

00:28:11.840 | It's very clear that these fermented foods

00:28:14.280 | support the microbiome,

00:28:15.880 | that we should be ingesting at least two servings per day,

00:28:19.480 | which is quite a lot,

00:28:21.100 | that supplementation at low levels can be good.

00:28:24.600 | Supplementation at high levels can create this brain fog,

00:28:27.120 | even though some people say that result is controversial.

00:28:30.080 | I've experienced this myself,

00:28:31.360 | and the data look to me pretty darn solid.

00:28:34.920 | So that's one thing to think about as well.

00:28:38.400 | And the other thing about the gut microbiome

00:28:41.320 | is that it's highly contextual

00:28:43.000 | based on other things that you're doing.

00:28:44.540 | So even things like exercise

00:28:46.080 | and social wellbeing and connection,

00:28:48.020 | those things are also impacting the gut microbiome.

00:28:50.120 | So find the diet that's right for you

00:28:52.120 | and that works for you in the context of the other

00:28:55.400 | ethical and lifestyle choices that are important to you.

00:28:58.240 | That's my advice.

00:28:59.260 | So as we round up,

00:29:00.200 | I want to share some results with you

00:29:02.480 | that without question will impact the way

00:29:05.640 | that you respond to food mentally and even physically.

00:29:10.280 | I have a colleague at Stanford,

00:29:12.320 | Aaliyah Crum, who's done some remarkable experiments

00:29:15.800 | on mindset, two that are particularly interesting to me

00:29:20.800 | I want to share with you now,

00:29:21.900 | because they really emphasize how our beliefs

00:29:25.260 | can really impact the way

00:29:26.520 | that our brain and body work together.

00:29:28.740 | I think the most famous of these is an experiment they did

00:29:31.260 | where they had two groups of individuals.

00:29:33.280 | They were each given a milkshake,

00:29:36.940 | and they had some factors measured from their blood

00:29:41.020 | by an IV while they ingested the milkshake

00:29:43.460 | and then afterwards as well.

00:29:45.520 | And one of the factors that they were looking at

00:29:47.940 | was something called ghrelin, G-H-R-E-L-I-N.

00:29:51.900 | Ghrelin is a peptide that increases with hunger.

00:29:54.980 | So the longer you haven't eaten, the ghrelin goes up.

00:29:57.620 | One group got a shake that they were told

00:30:00.260 | was a low calorie healthy shake.

00:30:02.380 | The other group got a milkshake that they were told

00:30:05.980 | was the very decadent high calorie shake.

00:30:10.180 | And what they found was that the high calorie shake

00:30:13.820 | had a much more robust effect on blunting ghrelin

00:30:17.720 | and reducing ghrelin.

00:30:19.520 | But the interesting thing you probably guessed already

00:30:22.640 | is that it was the exact same shake given to both groups.

00:30:26.360 | And this speaks to the so-called top-down mechanisms

00:30:30.360 | or modulation of our physiology.

00:30:32.600 | In a previous episode about pain,

00:30:33.840 | we talked about the effects of obsessive infatuation

00:30:37.960 | and love on pain responses and pain thresholds.

00:30:40.920 | This is yet another example where beliefs

00:30:43.300 | or subjective feelings can impact physiology

00:30:46.200 | at the level of the periphery,

00:30:47.340 | because ghrelin is released in the periphery in the body.

00:30:50.900 | And so this is not just the placebo effect,

00:30:54.300 | this is an incredible set of findings

00:30:56.700 | that illustrate the extent to which

00:30:58.300 | whether or not we believe a food is going to be good for us

00:31:01.180 | or not good for us.

00:31:02.900 | These belief effects are not about lying to yourself.

00:31:05.860 | So in order for them to work,

00:31:06.980 | you have to be naive to the information, right?

00:31:10.580 | You can't simply lie to yourself

00:31:12.200 | and tell yourself what you want to believe.

00:31:14.640 | And that's important,

00:31:16.200 | but also important is that the mind and the body

00:31:19.820 | are in this fascinating interplay.

00:31:21.680 | And today we've talked mainly about how the body

00:31:24.740 | and things that we put inside this tube

00:31:27.960 | that runs from our mouth to the other end,

00:31:31.080 | to our rectum basically is impacting all these cells,

00:31:34.920 | these neurons, microbiota in their mucosal lining,

00:31:39.960 | heart, lungs, and how all that information

00:31:42.060 | is feeding up to the brain to impact how we feel up here.

00:31:44.980 | But also how we feel up here is impacting

00:31:47.620 | how our body reacts at levels of very core physiology

00:31:51.760 | that you couldn't just tell yourself

00:31:53.740 | that this was going to work.

00:31:54.780 | But what you believe about certain substances,

00:31:57.980 | certain foods, certain nutrients

00:31:59.900 | does have a profound effect on the magnitude of their impact

00:32:04.140 | and sometimes even the quality

00:32:05.820 | and direction of that impact.

00:32:07.920 | So today's episode, we took a full journey

00:32:10.340 | into the brain-body relationship

00:32:11.980 | and discussed a lot of the mechanisms

00:32:13.820 | and the actionable items that you can approach

00:32:16.540 | if you want to explore this aspect

00:32:18.220 | of your biology and psychology further.

00:32:20.500 | Last, but certainly not least,

00:32:22.660 | I want to thank everybody for your time and attention today.

00:32:25.340 | And as always, thank you for your interest in science.

00:32:28.440 | [upbeat music]

00:32:31.020 | (upbeat music)

How Foods & Nutrients Control Our Moods | Huberman Lab Essentials

Chapters