The microbiome of the gut makes neurochemicals like dopamine, serotonin, and gamma-
One of the best known experiments linking the gut bacteria to the brain was published in Proceedings of the National Academy of Science in 2011, The research team at University College Cork, in Ireland, and McMaster University, in Ontario was lead by Dr. John Cryan, whose Ted talk is featured in this article, with co-author Ted Dinan. Thanks to Ted Dinan you can see the slides summarizing their findings.
There are other scientists furiously at work determining the nature of the bacteria that live in the bowel.
Here is an article in the New York Times with an inside look into Dr. Lyte's lab, where he studies the behaviour of the microbiome and its relationship to our health. (My bold)
Lyte’s interest was not in the feces per se but in the hidden form of life they harbor. The digestive tube of a monkey, like that of all vertebrates, contains vast quantities of what biologists call gut microbiota. The genetic material of these trillions of microbes, as well as others living elsewhere in and on the body, is collectively known as the microbiome. Taken together, these bacteria can weigh as much as six pounds, and they make up a sort of organ whose functions have only begun to reveal themselves to science. Lyte has spent his career trying to prove that gut microbes communicate with the nervous system using some of the same neurochemicals that relay messages in the brain.
Inside a closet-size room at his lab that afternoon, Lyte hunched over to inspect the vials, whose samples had been spun down in a centrifuge to a radiant, golden broth. Lyte, 60, spoke fast and emphatically. ‘‘You wouldn't believe what we’re extracting out of poop,’’ he told me. ‘‘We found that the guys here in the gut make neurochemicals. We didn't know that. Now, if they make this stuff here, does it have an influence there? Guess what? We make the same stuff. Maybe all this communication has an influence on our behavior.’’Photo
Credit Illustration by Andrew Rae
Since 2007, when scientists announced plans for a Human Microbiome Project to catalog the microorganisms living in our body, the profound appreciation for the influence of such organisms has grown rapidly with each passing year. Bacteria in the gut produce vitamins and break down our food; their presence or absence has been linked to obesity, inflammatory bowel disease and the toxic side effects of prescription drugs. Biologists now believe that much of what makes us human depends on microbial activity. The two million unique bacterial genes found in each human microbiome can make the 23,000 genes in our cells seem paltry, almost negligible, by comparison. ‘‘It has enormous implications for the sense of self,’’ Tom Insel, the director of the National Institute of Mental Health, told me. ‘‘We are, at least from the standpoint of DNA, more microbial than human. That’s a phenomenal insight and one that we have to take seriously when we think about human development.’’
Given the extent to which bacteria are now understood to influence human physiology, it is hardly surprising that scientists have turned their attention to how bacteria might affect the brain. Micro-organisms in our gut secrete a profound number of chemicals, and researchers like Lyte have found that among those chemicals are the same substances used by our neurons to communicate and regulate mood, like dopamine, serotonin and gamma-aminobutyric acid (GABA). These, in turn, appear to play a function in intestinal disorders, which coincide with high levels of major depression and anxiety. Last year, for example, a group in Norway examined feces from 55 people and found certain bacteria were more likely to be associated with depressive patients.
It's worth reading the whole article which includes some of the history of the scientific interest in the microbiome. There seems to be more interest in the bacteria, but there are other living organisms living in the bowel such as parasites, viruses and fungi.
Some of the studies don't seem to have clear outcomes. There are so many variables for one there are organisms in the bowel that still can't be cultured! How are they influencing the production of neurochemicals and the immune system.
I have a theory that the diets of the subjects are not controlled for the types of carbohydrates they eat, nor control over the amounts of chemical are in the diet. Processed food has more additives such as natural flavours and home cooked has less chemicals, where all chemicals can change the expression of the microbiome through altering the expression of single cells genetics especially their methylation genetics (MTHFR).
The specific carbohydrate diet first developed by Dr. Haas, and modified to become the GAPS diet, has been successfully used, for over half a century to heal patients with all sorts of mental and physical complaints. It's foundation is homemade, unprocessed food, high in immunoglobulins, and probiotics and it works by changing the microbiome. I rarely have to add a medical treatment to the GAPS protocol once the cholesterol, vitamin D, magnesium and omega 3 levels are normal.
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