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The Mind–Gut Connection: Psychiatry and Gastroenterology

Updated: Jan 26, 2022

The Mind – Gut Connection: Psychiatry and Gastroenterology

In his 2018 book, The Mind-Gut Connection, Emeran Mayer, MD sets the tone for a rich, elaborate discussion informing us regarding the connections between the gastrointestinal tract, the immune defenses and the brain. He writes, “Until now, we have largely ignored the critical role of two of the most complex and crucial systems in our bodies when it comes to maintaining our overall health: the gut (the digestive system) and the brain (the nervous system). The mind-body connection is far from a myth; it is a biological fact, and an essential link to understand when it comes to our whole body health.”

We Are Outnumbered: The Body in Perspective

So who are we? Really? Dr. Mayer elaborates on the question, “More than 100 trillion microbes live in the dark and nearly oxygen free world of the human gut – about the same number of all the human cells in the body, if you include the human red cells in this comparison…If you put all your gut microbes together and shaped them into an organ, it would weigh between 2 and 6 pounds – on par with the brain, which weighs in at 2.6 pounds. The 1,000 bacterial species that make up the gut microbiota contain more than 7 million genes – or up to 360 genes for every human gene.”

Not at all surprising, your 100 trillion gut microbes greatly affect who you are, your body overall and your brain in particular. As Dr. Mayer notes, “no matter what you feed them, they will use their enormous amount of information stored in their millions of genes to transform partially digested food into hundreds of thousands of metabolites.”

The Little Brain in Your Gut

How does your gut take the food on your fork, make use of it in supplying your body with nutrients and get rid of the waste? Dr. Mayer answers, “The gut can coordinate all of this and more without any help from your brain or spinal cord, and it is not the muscles making up your gut wall that know how to do it. Instead, managing digestion is largely the work of your enteric nervous system (ENS) – a remarkable network of 50 million nerve cells wrapped around the intestine from the esophagus to the rectum. This “second brain” may be smaller than its three-pound counterpart in your head, but when it comes to digestion, it’s brilliant.”

Food Addiction: A Struggle of Our Two Brains to Keep Us Healthy

Dr. Mayer elaborates on the effect of our American environment of a high fat, high sugar modern Western diet and the food cravings that can result and bedevil us. “How much food you eat is controlled by three closely interacting systems in your brain: in addition to the appetite control system regulated by the hypothalamus, there are two other brain systems that play a prominent role: the dopamine reward system, and the executive control system, located in the prefrontal cortex, which can voluntarily override all other control systems if needed.”

Dr. Mayer describes the mind-gut connection and food addiction. “Not surprisingly, there are very close connections between the brain’s reward system and the networks involved in appetite regulation. For example, a number of gut hormones and signaling molecules influence activity in the dopaminergic reward pathway: several appetite-boosting signals increase the activity of dopamine- containing cells, while certain appetite-suppressing signals decrease dopamine release.”

Dopamine is the brain neurotransmitter that tells you, both consciously and unconsciously, “go for it -you got to have it.” While dopamine is necessary for the preservation of the individual and the human species, such as in avoiding danger and initiating sex, it is central to all addictive behavior.

Dr. Mayer describes, “Certain foods, especially high-calorie foods rich in fat and sugar, have been shown to trigger addictive eating behavior in both animals and humans…These mechanisms not only promote overeating and but also produce learned associations, also called conditioned responses, between the stimulus of the food and the reward signals in the brain.”

Taking Charge of Your Mind-Gut Connection: Become Healthier

Dr. Mayer instructs us in taking control of our lifestyle and becoming healthy, benefiting your gut, your brain and your entire body.

  • Aim to maximize gut diversity by maximizing regular intake of naturally fermented foods and probiotics.

  • Reduce the inflammatory potential of your gut by making better nutritional choices.

  • Cut down on animal fat in your diet.

  • Avoid, whenever possible, mass-produced, processed food and select organically grown food.

  • Eat smaller servings at meals.

  • Reduce stress and practice mindfulness.

  • Avoid eating when you are stressed, angry, or sad.

  • Enjoy the secret pleasures and social aspects of food.

  • Become an expert in listening to your gut feelings.

Dr. Mayer predicts, “Now that we are beginning to fully understand the marvelous complexity of universal connectiveness…I am convinced that we will view the world, ourselves, and our health with very different eyes.”
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