How Your Gut Influences Your Mental Health: It’s Practically a Second Brain | Dr. Emeran Mayer

The Mind-Gut Connection is something that
people have intuitively known for a long time but science has only I would say in the last
few years gotten a grasp and acceptance of this concept. It essentially means that your brain has intimate
connections with the gut and another entity in our gut, the second brain, which is about
100 million nerve cells that are sandwiched in between the layers of the gut. And they can do a lot of things on their own
in terms of regulating our digestive processes. But there’s a very intimate conversation
between that little brain, the second brain in the gut and our main brain. They use the same neurotransmitters. They’re connected by nerve pathways. And so we have really an integrated system
from our brain to the little brain in the gut and it goes in both directions. The little brain, or the second brain, in
the gut you’re not able to see it because as I said it’s spread out through the entire
length of the gut from your esophagus to the end of your large intestine, several layers
of nerve cells interconnected. And what they do is even if you – and you
can do this in animal experiments if you completely disconnect this little brain in the gut from
your main brain this little brain can completely take care of all the digestive processes,
the contractions, peristaltic reflex, regulation of blood flow in the intestine. And it has many sensors so it knows exactly
what’s going on inside the gut, what goes on in the wall of the gut, any distention,
any chemicals. All of this is being picked up by these sensory
nerves, fed into the interior nervous system, the second brain. And then the second brain generates these
stereotypic responses. So when you vomit, when you have diarrhea,
when you have normal digestion, all of this is encoded in programs in your second brain. What the second brain can’t do it cannot
generate any conscious perceptions or gut feelings. That really is the only ability that allows
us to do this and perceive all the stuff that goes on inside of us is really the big brain
and the specific areas and circuits within the brain that process information that comes
up from the gut. Still most of that information is not really
consciously perceived. So 95 percent of all this massive amount of
information coming from the gut is processed, integrated with other inputs that the brain
gets from the outside, from smell, visual stimuli. And only a very small portion is then actually
made conscious. So when you feel good after a meal or when
you ate the wrong thing and you’re nauseated those are the few occasions where actually
we realize and become aware of our gut feelings. Even though a lot of other stuff is going
on in this brain-gut access all the time. When we talk about the connection between
depression and the gut there’s some very intriguing observations both clinically but
also now more recently scientifically that make it highly plausible that there is an
integrate connection between serotonin in the gut, serotonin in our food, depression
and gut function. On a clinical level there’s a connection
because many patients with depression also complain of constipation. So a distinct dysfunction of the gut. And often the medications that people with
depression take, particularly the serotonin reuptake inhibitors such as Prozac and all
the other drugs in this category, they often cause transient gastrointestinal dysfunction. So that’s on the clinical level. However, what makes it particularly interesting
and still an open question really more than 95 percent of all our serotonin we have in
our organism is really produced and stored in the gut in specialized cells, so-called
enterochromaffin cells. So our major by far the largest store of that
molecule that plays such a big role in modulating our mood and our wellbeing, also appetite,
pain, sensitivity is stored in the gut. And a lot of very interesting discoveries
have been made more recently that makes this even more intriguing. So this serotonin is synthesized in the gut
from precursors that come from our food that we ingest and the microbes that live in the
gut are actually able through chemicals that they produce to stimulate the production of
serotonin. It’s been estimated based on studies in
animals that 60 percent of the production is due to these signals that come from the
microbes that live in our gut. So in addition another intriguing finding
is that these serotonin cells, so they’re sandwiched in between the cells that make
the lining of the gut. One end sticks into the inside samples, everything
that goes on inside the gut. The other side very interestingly has an outgrowth
which connected through a synapse with sensory nerve endings. So many vagal nerve endings. So this is a cell that sticks into the gut,
samples a lot of things that go on in our digestive tract. Then it produces serotonin largely through
the influence of microbes that live in our gut and then the signal when this cell is
activated there’s many things chemical or mechanical stimuli associated with digestion. It signals through this synapse directly into
our brain through the vagus nerve into centers that have to do with – I mean ultimately
with emotional regulation and emotion generation. So even though we don’t have the proof for
that it would be very difficult to mention that there’s not a significant influence
on our mood and that this system if it’s out of balance does not play a significant
role in the pathophysiology of depression. There’s many food items that contain neuroreactive
molecules signaling substances including oysters, chocolate and many other foods that to varying
degrees contain either the precursors of serotonin or actually serotonin molecules. It’s possible that these contents of this
molecule are the basis for some of these claimed effects of food items like oysters as an aphrodisiac
or mood enhancer like with chocolate. People say they feel a lot better after they
eat their daily piece of chocolate in the evening which is pretty true. Not just from the taste but from this chemical

81 thoughts on “How Your Gut Influences Your Mental Health: It’s Practically a Second Brain | Dr. Emeran Mayer

  1. True Depression, and i dont just mean feeling a bit low, is one of the worst things a person can go through. I have put together the biggest collection of vi deos about Depression, in two folders in the play list part of my chnl. Hope they are useful to someone going through depression ? Please thumb this up so others will be able to benefit from the information. Thanks

  2. "Don't listen to your gut" – Scientists
    "Listen to your gut" – Scientists
    "Depression is a brain imbalance." – Scientists
    "Oh, actually depression isn't in the brain." – Scientists

  3. What about, when you get some upsetting news and feel nauseated or have diarrhea because of it? To me that proves that connection.

  4. if you think about it, the gut actually looks like a brain if you put it together. only much larger and hollow, so im not surprised its starting to be considered the secondary brain.

  5. But I just ate a big burger and I feel great. These are tears of joy, I promise. I'm just cutting myself with joy, I promise. I like standing on this bridge.

  6. So feedback from an organ to the brain is somehow indicative of a "second brain" that he admits isn't really a brain but a nerve network that he suspects can do a number of complex tasks, but admits that there isn't really any proof of any of it, yet still has a "gut" feeling that it's true? Does he link a single study to back this all up? Nope. It's a web of theory at this point, and even if it does pan out to be a legitimate theory, there's nothing stopping an army of naturopaths and Mercola / Oz worshipping quack enthusiasts from exploiting the shit out of this to push their anti MD agenda on their yoga buddies.

    You got the yeast-phobic groups, the gluten free hipsters, and the "probiotics can cure everything" group lining up to jerk off to this already.

    There's certainly nothing wrong with a scientist having a theory. that's not my issue. it's the quacks ready to exploit theories to sell products that piss me off. be sceptical!!!

  7. From my experience, i have felt very bad mood swings and depression and a very overall crappy feeling for days if i play competitive video games. When i play these games i often am in Flight or Fight mode, constantly releasing adrenaline and cortisol and my stomach feels not easy, feels tight. These games require you to have full focus with very fast reflexes so it leaves my body feeling on edge. Ive noticed if i dont play these high intensity competitive video games, yes i might not have that fun feeling while playing, but if i just chillout and watch tv instead, i feel more stable and in a better mood, and the next day at work i feel much better overall too. High stress video games really bothered my gut and mental health

  8. So I guess an ulcer would be the reversal of the digestive process where one would feel like he's literally eating his own words, or thoughts for that matter

  9. People have known this since ancient times. The phrase "a healthy mind in a healthy body" sums it up pretty well. Perhaps with all of our distractions today we ignore our physical or mental health and, if not corrected, both can spiral downward.

  10. woooow news breaking. medical science is so late. you idiots can't even get the homosapien diet defined. Without defining what that diet is. you could never ever get the gut flora correct. news flash your a herbivore. Study primates all the living primates they are all herbivores. The strongest of them all eats nothing but plants. but I need milk and protein right? lots of bread too, more beef? let's cut down 90% of the rain forest so we can have more milky milk. lmao 😂 Medical science is a major joke. You should be very wary of what you see propagated through the circulating media. Keep drinking your fluoride, you fuckin retards.

  11. Thumbs up for helping me get tired enough to go back to bed. Seriously, interesting topic, and it forced my brain (brains?) to work, and now I'm finally tired. Thanks!

  12. I have depression and digestive problems aswell. I'm living a real nightmare with no ending. Everyday is a struggle again the disease. I can not working, I have lost everything I had. This is the second time I heard about the connection between dep and guts. Next time I'm going to ask to my doctor about this.

  13. I ruined my gut biome with wheat, antibiotics, milk, and overconsumption of gluten/processes foods back when I was 18-19,
    Main culprits were wheat & milk. There's also no enzyme activity once milk is ultra pasteurized & no benefit especially since the most nutritious part of it known as colostrum is destroyed.

    I noticed I never got paranoia before til that damage, my anxiety would shoot up and I noticed negative thoughts going haywire…my attention to my attention being the observer of my mind gets thrown off and I get more in flight or fight mode.
    Researched constantly what was wrong with me and found that connection and that others had found it before me. Intuition will guide you directly to your answers "all answers are within." Lol.

    Forget his name, but there's a Dr. Who has done mass studies in prison with experience of like 150,000 patients including schizophrenics, and other mental health problems (need to recheck for accuracy..)

    They found switching from a gluten free diet, drastically reduced, their symptoms…when you study nutrition/neuroscience you see why…you will find this theory yourself…
    I still eat it sometimes but massively take the steps to optimize digestion and reduce inflammation after.


    it's all just inflammation and lack of nutrients/energy that all dis-ease comes from.
    Checkout orthomolecular nutrition,
    Do a genetic test and see what nutrients and what your body needs/rule out your food allergies etc.

    Food allergies do damage of course, thus affect the mind.

    Perspective…people who are in the field of healing, mean well…selling products, giving free experiential/clinical/ or general educated advice, to help those. Yes some people do not have strong intuitive inner guide connection, have good discernment and look externally, dr to dr. Not root cause, medicating (MD's do not address the root cause, will not say oh you have this problem? It's a lack of this nutrient, combined with your diet,) and I am not saying distrust Dr.'s…there just needs to be integration, naturopaths is the new paradigm..

    I think no matter what you came here, learned this, for a reason…intuition guides you to the truth for you are truth.

  14. Dude, what the hell?!!!?! For someone who claims to know about mental health, this Dr. Mayer should learn something about misphonia.

    I really REALLY wanted to watch this video. I couldn't last halfway before literally spazzing out and throwing my keyboard away. I wanted to slap his stupid face, like a child who hasn't learned his manners. At the very least you editors and producers over there at Big Think could have the awareness to realize how inappropriate his smacking between statements is and maybe at least edit it out. But it is so not difficult to avoid making those sounds when you speak. Any decent professional speaker does it. People who talk like this do not belong in front of a camera.

  15. This a very interesting video and well explained.
    As a psychologist and medical student and someone who has an anxiety disorder often related of course with depression, I can tell you that this is so true, and I'm looking forward for more studies about this.
    Thank you Dr. Mayer.

  16. hahahaha… this is science. what you talking bout gut feelings 😂😂😂😂😂😂 jeez ❤ gut gut gut👌 oh.. i know what ya mean )

  17. The biggest problem with this video is that he goes on about how most of the serotonin in our body is produced by our gut…
    What he fails to mention is that most of that serotonin never crosses the blood-brain barrier!!
    Serotonin in the brain is primarily produced by the pineal gland, from tryptophan. So, the tryptophan metabolism in the gut has the influence on serotonin the brain. Of course, serotonin is important for various gut functions and pain modulation, vascular function in the periphery and that obviously can influence mental health.
    Bottom line is, the video is quite inaccurate and misleading.

  18. Perfectly said Dr. Mayer, thanks. My MSc degree thesis was in nutrition and I have worked academically and commercially in various countries for 35 years and have been saying basically the same things you mentioned since then. I observed with my own eyes "quasi-miracles" with the use of probiotics. The Japanese, where I worked partially for my MSc thesis, have been recommending this for decades. Wheren't them, at least one of the first ones, to recommend, the now world known, Yakult?

    I have no doubt whasoever that probiotics will play each time a more important role in human (and animal) nutrition and health, in many areas. It is narrow-minded naive to believe that all bacteria are bad. What we have to do is to select and promote the good/beneficial bacteria and other microorganisms and provide or induce them to "take the place" (at least in a greater extent) of the bad ones in our bodies and enviroments.

    Am confident that in a not distant future we will have toothpastes, bath soaps, foods, detergents etc that will provide good/beneficial bacteria instead of trying to kill them all. How many billion years they've been on earth, surviving and triving in all types of ambient circunstances? Humans are just children in this planet though the damage we made to the "mother nature" (Gaia) is growing to be irreversible, soon.

  19. Very curious whether the damage done to intestinal flora from an antibiotic like Clindamycin, which I recently took for a leg infection, might have contributed to a bad bout of depression that hit me a few days after finishing the antibiotics (along with mild diarrhea and other Clindamycin side effects), and which I'm still dealing with, though the infection is healing up nicely. Basically my good bacteria were pretty well wiped out (and I'm taking some probiotics to help prevent C diff), but I feel like crap, and am more depressed than I've been in a long time, though I felt pretty good last week. I'm not taking any other medications, just some nutritional supplements, but what's your opinion on the connection between powerful antibiotics and depression (though diarrhea is more of an issue in this case than "constipation" is). Thank you… and thanks for the video!

  20. Here is an example of the way modern science needs to separate the body into many parts. Everything is communicating to everything else on some level. Big pharma wants to target one thing to chemically bandage a perceived problem. In this video they speak of the gut having a large response on the well being of someone, another example is that feeling of having a hole in your heart when someone you love ends the relationship. That sensation of emptiness is localized at where the heart is. These feeling most likely radiate throughout the whole body. It's a Mind-Body Connection.

  21. i have had depression for 25 years. I been on all the meds and so called "natural" treatments, psychotherapy, yadayada…..
    I starting hearing about probiotics for helping depression. I watched a documentary called" The Gut our Second Brain " on Amazon. Check it out. After watching that and doing some research on my own I started taking high quality probiotics in pill form for 4 weeks and guess what ? PROBIOTICS HAS HELPED ME TREMENDOUSLY. No B.S. either. I continue to take Lamictal as a mood stabilizer but no longer take or need an antidepressant. I also take high quality fish oil, B12, and Vit D. I added the probiotics and have not felt this good in a looooonnnngggg time. Do yourself a favor and try it for 1 month. Do some research on this and you will be surprised…………. I take "Flora UDO's Adult's Probiotic".

  22. Would fasting help to cure the depressing feelings from the gut to brain after eating unhealthy and too much?

  23. You want to harness dopamine? Then indulge in pleasurable activities. That's why people go shopping roaming dressing talking bla bla boasting betting gambling playing stupid games. Yeah artistic works professional work etc.

  24. So many ignorants in the comments it makes me sad.:( all the people disagreeing are obviously self conscious that they are eating unhealthy. Plus they are the only negative ones in the comments. Lol which basically proves the point of this. Try eating healthy and then tell me that it doesn’t make you feel better.

  25. In a nutshell "the body can control smooth organs without you thinking your hotdog into a turd, be thankful"

  26. I get severe depression eating certain foods. My genetically low cholesterol makes them very black. This started at perimenopause.

  27. The YT comments here are mostly gutty witty Lol. I suspect by the gut that most are into biology, nutrition or medicine.

  28. Liver and gallbladder stones is the root cause of gut problems which cause depression…..look into Andreas moritz liver flush

  29. This Dr. is onto something. I had major depression for 4 months then I developed IBS-C. Having a poor functioning bowel gives me depression. There is 100% a connection between brain and gut.

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