The Second Brain- in your Gut

By Doc Don Davis            ………………

Today I’d like to talk about a second brain that we all have that resides in our intestines.  You would think one brain would be enough, but we actually have two brains; one at the top of the spinal cord and one large, powerful “brain” in the gut, called the enteric nervous system.  Anyone that has given a speech and experienced the predictable performance-related stomach distress knows that your gut is listening closely to your brain.  But what can the brain learn from the stomach?  As it turns out, plenty.

You see, the brain and the gut, including the esophagus, stomach, small and large intestine, and colon are intimately connected by the huge vagus nerve in a two-way street. Scientists were recently shocked to learn that about 90 percent of the vagus neurons carry information from the gut to the brain and not the other way around. In fact a new successful treatment for depression is vagal nerve stimulation, which shows that gut activity has a direct effect on the brain’s sense of well-being.

This means that your general state of mind and your emotions are greatly affected by the health of your gut.  This can happen because there is a  “second brain” in the gut is so extensive (100 million neurons) that activities of the gut are a major influence on the brain.  Many studies have shown that this constant exchange of electrical messages and chemicals are actually considered to be one entity and form the “brain-gut axis.” This is why ailments like irritable bowel syndrome, ulcers, Parkinson’s and depression have symptoms at both the gut and brain level.  Patients with anxiety will have problems in the gut, and patients with heartburn will have changes in the brain.

Unfortunately, drugs have been the first approach to controlling symptoms and have many side effects related to the brain-gut axis.  Drugs used for depression (SSRI’s) increase the levels of serotonin in the brain but because 95% of the serotonin in the body is found in the digestive system, taking SSRIs can lead to GI problems such as nausea, constipation or diarrhea–what some call “mental illness” of the second brain.  Increased serotonin in the gut also has the surprising affect of increasing the incidence of osteoporosis.

Valium and sleeping pills affect the brain, but also depress gut function (via GABA receptors) leading to constipation, indigestion and colon spasms.  Almost every hormone or neurotransmitter the brain needs to function is also located in the gut and is effected by gut health, as are the major cells of the immune system or GALT (Gut Associated Lymphoid Tissue).

Even sleep is disturbed by poor communication between brain and gut. Most people know of the 90-minute cycles of REM sleep (dream sleep) but the gut also has 90-minute cycles of slow wave muscle contractions followed by short bursts of muscle movement.  People with bowel problems like irritable bowel syndrome or Crohn’s
Disease have abnormal REM sleep because of this relationship between REM sleep and gut contractions.

Most people don’t realize that the gut has such a significant role in emotions and well-being. Unfortunately, because of this, digestive health is often overlooked as a major contributor to brain function or overall health.

Many psychiatrists are now beginning to understand this relationship and seek the help of functional medicine experts to help direct their care.  Testing gut function by measuring the levels and species of good bacteria can be very helpful along with looking for malabsorption, H. pylori (the bacteria that causes ulcers),  parasites, and the most common irritant, gluten.  These tests along with information on the adrenal glands that evaluate problems related to sleep and stress can go a long way to formulating a plan to get back on track with both the “first” and “second brain”.


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