Here’s Scientific Evidence Why You Should Follow Your Gut Feeling?

Here's Scientific Evidence Why You Should Follow Your Gut Feeling?


  • 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.


Depression and the Gut:

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. 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!!

Does the Gut influence Sleep?

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.

The Brain-Gut Co-relation:

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:

  • if the gut is not functioning well – we do not absorb the nutrients we need to support a healthy body and brain
  • nutrient needs to get from the gut to the liver; be metabolized; and then sent to the brain for further metabolization and use
  • 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
  • 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:

  • neurotransmitters
  • hormones
  • vagus nerve
  • 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.”

Dr Gershon’s study, reported in The New York Times article, identified how Prozac effects the gut. A guinea pig colon was mounted on a stand. First, they put a millet in the “mouth” end of the colon, and the pellet moves through the colon as it normally would. Then the researchers put a small amount of Prozac into the colon, the pellet “went into high gear,” Dr. Gerhson explained to the paper. “The drug doubled the speed at which the pellet passed through the colon, which would explain why some people get diarrhea,” the paper says. No wonder, in small doses, Prozac is used to treat chronic constipation.

Like so many herbs and foods, different strengths have different impacts on the system. In this case, a little works to eliminate constipation while a lot provokes constipation. If there is a disruption in the production, secretion or regulation of:

  • neurotransmitters
  • hormones
  • anti-inflammatories
  • enzymes
  • fatty acids
  • etc

in one system – it can have a direct or indirect impact on the other system.


How the Gut produces Anti-Depressants:

For instance, Alzheimer’s and Parkinson’s disease patients are constipated. A sickness we think of as primarily affecting the brain or central nervous system also impacts the gut.  The nerves in their gut are as sick as the nerve cells in the brain. Our gut also produces chemicals called benzodiazepines.

Pharmaceutically, benzodiazepines are considered one of the worst group of synthetic chemical drugs produced and are the basis for anti-anxiety drugs like valium and various pain relievers.  The man made synthetic version of these chemicals can be very destructive but our gut makes its own natural benzodiazepines that also relieve anxiety and pain.

While it is not yet confirmed whether the gut creates benzodiazepines from chemicals in our foods, bacterial actions, or both, we do know that in times of extreme pain, the gut goes into overdrive, delivering benzodiazepine to the brain. The result is to render the patient unconscious or at least reduce the pain, says Dr. Anthony Basile, a neurochemist in the Neuroscience Laboratory at the National Institutes of Health in Bethesda, Maryland.


Immunity and the Gut:

Another component that needs to be addressed is the immune system. The majority of the immune system also resides in the gut. Thus, if there is a challenge with a compromised immune system and/or the gastro intestinal system – it can have a very direct impact on both brains.

The brain and the gut/immune system have a very direct communication through specialized cell messengers called cytokines (released from white blood cells in the gut and by glial cells in the brain): pro-inflammatory and anti-inflammatory. Recent science has recognized that when the pro-inflammatory cytokines (which are predominately secreted in the gut) are consistently raised, we suffer from:

  • Lack of energy
  • Lack of appetite
  • sleep disturbances
  • changes in mood
  • loss of interest


How the Gut influences your Anti-Stress response:

When the balance between the pro and anti-inflammatory cytokines is not balanced, we respond:

  • to psychological issues like stress:
  • a physical threat in form of a virus or bacteria
  • or to a physical trauma, ie., accident
  • AND some people may develop depressive episodes.

The resulting depression is not a reactionary depression, ie., in response to the illness; but is caused by cytokines provoking an immune system which has lost its ability to return to a state of neutrality. Unfortunately, anti-depressants can further inhibit the production of these crucial anti-inflammatory cytokines; thus increasing the problem rather than solving it. Various nutritional factors:

  • can increase the necessary bacteria in the gut
  • increase the anti-inflammatory cytokines support the gut
  • can increase the capacity of the gut to function effectively
  • can provide the liver with the necessary nutrients to function and support the brain

For example, essential fatty acids are required to help these “friendly” bacteria stick to the gut wall and reduce pro-inflammatory cytokines. This not only improves the gut but also improves brain function.

The brain is made up of about 60% fat and a significant amount of this are the fatty acids, ie., palmitic, oleic, lineolic, etc.  These fats are the structural components of the brain; create the insulation the neurons require; provide fuel and transport systems; and act as anti-inflammatories.

Thus, when considering either, functions of the brain and or functions of the gut – the other should always be taken into consideration. Diet and herbs should always be utilized to enhance the body’s natural healing mechanisms. We should always take the combined systems into consideration as they are all very interactive.

Once again, we have to realize that psychological issues may not be just in the head and likewise gut issues may not just be a gut issue.