Dr. HollyCan this impact on depression?

  • Have you ever thought of why your stomach reacts when you are upset?
  • Or why indigestion gives nightmares?
  • Or why we depend on our gut reactions?


Your stomach/gut is considered the “enteric nervous system” which complements our“central nervous brain”. One brain is the skull brain and the second is the gut brain. Both develop out of the same fetal tissue. It is well recognized that systems and organs that develop from the same fetal tissues have very interesting connections.

But after these two brains develop from the same fetal tissue they continue to be connected through one of the 12 cranial nerves called the vagus nerve. This vagus (latin term meaning wandering) nerve wanders from the brain stem through the neck down through the trunk of the body and creates a very strong brain body connection.

Some have argued that that is the reason anti-depressants can cause gut reactions, such as nausea. However, it is probably more likely that when the anti-depressant moves through the gut on the way to the liver, where it is metabolized, it provokes a reaction like many drugs do.

It was long hypothesized that low levels of serotonin caused depression. While there are several groups of anti-depressants based on this now recognized FALSE hypothesis, it is interesting to know that 98% of serotonin is made in the gut.

There is an excellent article on this brain-gut connection called Complex and Hidden Brain in Gut Makes Bellyaches and Butterflies written by Sandra Blakeslee, originally published in the January 23, 1996 issue of The New York Times.

As noted, the gut brain is called the enteric nervous system (ENS) and is located in a layer of tissue that lines the esophagus, stomach, small intestine and large intestine. This layer of the gastrointestinal tract contains neurons, neurotransmitters, proteins and hormones that configure messages just like the brain does.

In Dr Michael Gershon’s book The Second Brain, HarperCollins 1998, Dr. Gershon, a professor of anatomy and cell biology at Columbia-Presbyterian Medical Center in New York City, dubs the entire gastrointestinal system the body’s second nervous system. “The brain is not the only place in the body that’s full of neurotransmitters,” says Dr. Gershon. “A hundred million neurotransmitters line the length of the gut, approximately the same number that is found in the brain…” The combined number of nerve cells of the esophagus, stomach and large intestine, are more than there are in the entire remainder of the peripheral nervous system. Most of the chemicals that control the skull brain have also been identified in the gut, including hormones and neurotransmitters.

Even when the skull brain is dead, the gut brain can continue to function!!

Both the brain and the gut have natural 90 minute cycles. In the brain, the slow brain cycle is interrupted by the rapid eye sleep called REM sleep cycles. In the gut; the same 90 minute cycle occurs: slow wave muscle contractions interrupted by short bursts of rapid muscle movement.

Is it probable that these cycles reflect one another; interact with one another; suffer similarly? If we look at the brain REM cycle, we find that there is a corresponding altered activity in the autonomic nervous system and in the large intestine function. Also of interest, is that patients with bowel issues, like irritable bowel syndrome (IBS) and non-ulcerative dyspepsia (sour stomach) have poor sleep.  There are numerous parallels of this nature, but let’s move on.

Another similarity between the brain and the gut is that they both have protective barriers. The one in the brain is called the blood brain barrier (BBB) and the one in the gut is the mucosal protective barrier. Both are required to protect what is inside and prevent leakage.  When disruptions occur in either barrier – results are felt in both systems.  When there is inflammation in either system – both systems can feel the effect.

The brain gut connection happens in a different ways:

  • 1) if the gut is not functioning well – we do not absorb the nutrients we need to support a healthy body and brain
  • 2) nutrient needs to get from the gut to the liver; be metabolized; and then sent to the brain for further metabolization and use
  • 3) if the gut is not functioning well – we do not eliminate the toxins and waste we need to rid our bodies of these non-wanted elements can then get into the body and cause toxicity, oxidative stress, inflammation and further problems
  • 4) if the gut is not functioning well; the production and release of hormones, neurotransmitters, enzymes, etc will falter and cause problems with the gut and/or the brain

But the reverse also has an impact:

1) unhealthy thoughts and emotions impact on the gut through a variety of means:

  • a) neurotransmitters
  • b) hormones
  • c) vagus nerve
  • d) hypothalamic – thyroid – adrenal axis

2) taking anti-depressants preventing the reuptake of serotonin – not only happens in the brain but also in the gut cells that need this neurotransmitter. “Serotonin is calming to the digestive tract, initiates peristaltic and secretory reflexes,” notes nutritionist June Butlin, M.Sc., Ph.D. “Long-term use or the wrong dosage may cause fluctuations between nausea, vomiting, constipation and diarrhea, and can cause depression, anxiety, insomnia, and fluctuations in appetite.”


For more information, contact: Dr Holly at holly@choicesunlimited.ca

Disclaimer: This article is provided for general information only, and is not a substitute for the medical advice of your own doctor or other health care professional. The writer or publisher is not responsible or liable for any diagnosis made by a reader based on the content of this article. Always consult your own health care practitioner.