Review: The Gut Our Second Brain

Published 4.17.2017
The Gut: Our Second Brain is a video available on Amazon, free for viewing for Amazon Prime members, and otherwise I think it can be rented. These are the notes and commentary I had while watching the show.

The micobiome or microbiota of the human gut is an area of intense research and interest over the past few years. Researchers have only begun to try to understand how the millions of organisms. bacteria, viruses, protozoa and fungi interact in our guts and how it affects us. There are 200 million neurons in our gut, which is about the same as a cat or dog? The assertion in the show is that if they are intelligent, then so is our gut. This is the “gut brain” of the title.

The neurons line the digestive wall forming an enteric nervous system. The two brains communicate through the vagus nerve, and they use the same neurotransmitters. Serotonin in the gut sets the transit speed and affects the immune system. The claim is that 95% of serotonin is produced in the gut. This is the evidence as presented in the show, I haven’t fact checked all of this except where noted.
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Serotonin affects the hypothalamus, and the serotonin made in the gut gets to the brain, which is where the hypothalamus is. The vagus nerve starts in the brain and follows along the esophagus and goes to the stomach and eventually all the way to the colon. So it's another gut-brain linkage.

Irritable bowel syndrome (IBS) may be miscommunication between the mucosal cells and the intestinal nerve cells. Sick people have more nerve activity than well people. And of course they are looking for a drug answer.

Can use hypnosis to turn down the activity to lower pain— my woo sense starts to tingle. Hypnosis is the power of suggestion, and I will acknowledge that certainly pain response is in the brain, I’m all for getting people to alter their brain’s response in anyway possible. But you have to suggestible to have this work. And you have to want it to work. If you think it’s bunk it won’t work.

The gut might contribute to subconscious. So maybe Freud’s ego is in the gut? Maybe there will be a new filed of “gastro psychoanalysis?”

The two brains communication, therefore the two brains might share diseases. In fact, maybe the disease starts in the gut. Such as Parkinson’s Before intellectual symptoms show up, sufferers have constipation and other bowel issues, which I didn’t know. They have found the same lesion in the gut neurons as in the brain. That’s significant. Gut biopsies aren’t a big deal. Brain biopsies… different story. Looking into diagnose with the gut biopsies.

This research is being done in Nantes, France. I wonder if Alzheimer’s disease would be similar. Why isn’t this better known? Is the show overstating the facts? Perish the thought. Or the field in its infancy and just hasn’t been publicized yet in journals?

Woo Alert

More woo offered up. Now we are talking about chi and Chinese medicine: “invisible energy flow…” Then they talk about abdominal acupuncture. I don’t disagree that looking at the body holistically isn’t important… but Western medicine superseded Chinese medicine for a reason. At the center they visit, Chinese medicine is practiced along side western medicine. In other words, integrated or complementary medicine.

The chinese doctor claims there is a sensitive zone around the navel. He says the navel is a “hidden” system. What? My question is what does happen at the navel after birth? The following is derived from this site, which I did verify from other sources.

When the infant breathes for the first time the pressures in the lungs, and subsiquently, the heart change, closing the foramen ovale, an opening between the right and left artia. In a few cases, it doesn't close, causing an atrial septial defect, requiring open heart surgery.

The ductus arteriosus is a small vessel that also closes due to the pressure changes in the lungs. It takes a little longer to close, because it's dependent on blood flow to remain open. When it remains open, beyond the expected period, the surgery is less invasive, since the PDA is on the outside of the heart.

The navel is what remains after the umbilical cord falls off. What’s behind the navel in adults?

You've got it - the plumbing's gone. In a fetus, the umbilical cord contains two arteries and one vein, which connect to the fetus's iliac arteries and liver, respectively, and circulate blood into and out of the placenta. In a newborn infant, the umbilical vessels can indeed be used to administer drugs and fluids or to withdraw blood for testing. But as the child grows, those blood vessels (no longer useful after birth, since the placenta's gone) swiftly close off and eventually are reduced to narrow bands of fibrous tissue. There's nothing functional attached to the inside side of your umbilicus now, just a little bit of fibrous tissue connecting it to your liver.

The navel is a scar, there isn’t anything else attached to it. It just happens to be located near the “gut.” Shows like this don't help their argument showing nonsense like abdominal acupuncture. I suppose the argument could be that the needles touch nerves which are all interconnected, but that is not what was argued.
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Then the show move onto the microbiota. We have one to two kilograms of bacteria in us, and we have more bacteria then cells. They go to McMaster University in Canada and its research about the microbiata. The bacteria in us digests food that we can’t. Bacteria in the gut affects the immune system, which also makes sense.

Babies are born sterile, then get colonized. Ha! Over-cleanliness gets a mention for being bad. (No one will ever accuse me of having an "over-clean" house. On the hand, I have relatives whose houses are practically sterile they are so clean.

However, the notion that flora will be given to new borns or ill people to me is a stretch. Hubris is constant. That said, the treatment for c. difficile where they put the poop of healthy people into the colons of sufferers is pretty much just that, isn’t it?

They looked at the genome of the microbiota (which isn’t the genome of a single organism obviously), an effort that ended in 2010. That effort found that there are three enterotypes based on what populate our guts. Difference caused by gut bugs include the capacity to turn food into vitamins and things we can use. Gut flora also affect the ability to burn fat.

Enterotypes (gut bug differences) are not related to geography, but it’s likely to be related to food intake. The suggestion is that stool samples will become more common to analyze the microbiome. Different diseases may have a different gut profile.

Obese people rarely have one type of bacteria, but I missed the name of it. They showed in mice that adding that bacteria stopped obesity— which might upset HAES (health at every size) supporters.

The bacteria live in the mucous of the intestinal cells (hence the picture). I don’t believe that we will swallow these bacteria as treatment, how will it survive the stomach?

Obesity is 10% genetic, 10% bacteria, and 80% behavior. The energy balance still wins.

Now they talk about how the bugs within us might affect our behavior. This is, of course, mice studies. The can change mouse behavior by putting different bacteria into them. Which is interesting and a bit unnerving. Maybe you are what you eat?

It's not just bacteria, parasites and other organisms matter too. So can we do this in humans? Most of the data on probiotics are from those who are selling them. We don’t know how all this works at this point. It is clear that diet changes what lives in the gut.
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Probiotics and stress response is discussed, but this is all based on brain imaging. I am highly skeptical of results based on changes in brain images. I don’t think we understand the brain anywhere near enough to make definitive statements, such are offered in this show on this topic.

Side effects? They have no idea, so they do recommend caution. All we can say is that our brains see an effect from bacteria. We can’t say how though.

So suddenly we have three brains? The big one, the gut and now our fellow travelers in the microbiota. Hmm, since you can alter them, I’m saying, no to that concept.

I can accept that I’m an ecosystem, both inside and out, and I can accept that the scientists (almost entirely French) are excited by the possibilities. However, there are too many definitive statements made in this presentation for my tastes, and the tepid caution comes only at the very end.

I think the topic of the microbiome or microbiota of the gut is a fascinating area of research, but it is truly in its infancy. I’ve been involved with enough infant areas of research to be skeptical of grand predictions as to future advances. No, my experience is not in the nutrition or medical fields, but the over enthusiasm of pioneers is universal, I think.