Santa Monica Naturopathic Doctor | Amanda Frick, ND


Our Gut, The Second Brain

Posted on

Published by

If you’ve ever had your stomach in knots before speaking in public, then you know the stomach listens carefully to the brain. In fact, according to William Whitehead, PhD, a professor of medicine and an adjunct professor of psychology at the University of North Carolina, the entire digestive system is closely attuned to a person’s emotions and state of mind. People with irritable bowel syndrome often suffer symptoms during times of stress and anxiety, and even perfectly healthy people can have an increase of stomach pain, nausea, constipation or diarrhea during stressful life events.

In recent years the link between the nervous system and the digestive system has been recognized. There is a constant exchange of chemicals and electrical messages between the two systems. In fact, many scientists often refer to them as one entity; the brain-gut axis. Therefore, what affects the stomach will directly affect the brain and vice versa.

Medications designed to target the brain can also cause nausea, diarrhea, constipation or abdominal upset because the body actually has two brains – one encased in the skull, and a lesser known but vitally important one found in the human gut. Fat-soluble drugs penetrate the gut wall and can injure the natural balance of the digestive system. Antidepressants, benzodiazepines and sleeping pills are all fat-soluble, meaning they dissolve in fat and not water.

SSRIs (Selective Serotonin Reuptake Inhibitors) are believed to ease depression by enhancing levels of Serotonin to the brain. But 95% of the Serotonin in the body lies in the digestive system, and diverting the supplies of Serotonin from their natural receptors can increase anxiety, alter sleep patterns, cause sexual dysfunction and adversely affect the cardiovascular region. Balancing the hotbed of Serotonin production in the gut is critical to restoring the balance.

Some scientists believe that SSRIs boost Serotonin in the gut and change the signals to the brain, since antidepressants prevent the uptake of Serotonin by cells that should be using it. But Serotonin is calming to the digestive tract. This may explain why some SSRI users experience nausea, stomach upset, constipation, diarrhea, and fluctuations in appetite.

GABA receptors for Benzodiazepines and Sleeping Pills are also located in the gut and depress gastrointestinal movement, which can cause constipation. But the continued use of medications that target GABA also increase the level of stress on the body. And in many ways, the connection between stress and the gut may be the most visible brain-gut connection.  Chronic stress can result in indigestion, ulcers and a host of uncomfortable symptoms, including colon spasms. This may explain why the gut naturally produces benzodiazepines, to keep the natural state of calm that is necessary for proper functioning.

Nearly every chemical that controls the brain is also located in the stomach region, including hormones and neurotransmitters such as Serotonin, Dopamine, Glutamate, GABA and Norepinephrine. The gut contains 100 million neurons – more than the spinal cord. But there are also two-dozen small brain proteins; major cells of the immune system; one class of the body’s natural opiates; and native benzodiazepines. The gut, known as the enteric nervous system, is located in sheaths of tissue lining the esophagus, stomach, small intestine and colon, and plays a key role in human emotions. But few know the enteric nervous system exists, and therefore gut health is often overlooked. Symptoms from the two brains can get confused, and just as the brain can upset the gut, the gut can also upset the brain.

The brain signals the gut region by talking to a small number of command neurons, which in turn signal relay neurons that carry messages and control the pattern of activity in the gut. The term Solar Plexus simply refers to the nerves in the abdomen. But these plexuses also contain cells that nourish neurons and are involved in immune response and the protection of the “blood brain barrier” to keep harmful substances away from the important neurons. There are also sensors for sugar, protein, acid and other factors that monitor the progress of digestion, determining how the gut mixes and handles it’s contents.

During sleep, the head’s brain produces 90-minute cycles of slow wave sleep, followed by periods of rapid eye movement (REM) where dreams occur. During the night, when it is empty, the gut’s brain produces 90-minute slow wave muscle contractions, followed by short bursts of rapid muscle movement. These two brains are linked even in sleep. Individuals with bowel problems have been shown to also have abnormal REM sleep.

When the central brain encounters severe tension, it releases stress hormones that prepare the body for flight or fight. The stomach in turn contains many sensory nerves that are stimulated by this chemical surge – thus the feeling of butterflies. Fear also causes the Serotonin circuits in the gut to increase their intensity, resulting in diarrhea.

Both stimulation and inhibition are important to the normal transmission of messages. GABA neurons selectively slow the excited responses, which is why benzodiazepines are known to dampen experiences. GABA enhancing drugs such as benzodiazepines and sleeping pills perform a sedative force on the GABA receptors. But GABA is meant to only periodically regulate the excited transmissions, and the long-term intensification of GABA can decrease the receptor’s ability to reduce excitation – thus creating increased anxiety, insomnia and depression.

Sleep and waking is regulated by many neurotransmitters including Noradrenaline, Serotonin, Acetyl-Choline, Dopamine, GABA, the pituitary hormones and Melatonin. Any drugs that alter the balance of these neurotransmitters can also affect sleep. The answer is not to add more GABA, Serotonin or other chemicals, but to restore the equilibrium of chemical production.

There is a natural symphony of chemicals in the stomach region that balance our emotions, sleep, pain and energy. Benzodiazepines cause profound alterations throughout the brain and gut and an eventual reduction in GABA levels. Dose tolerance and abrupt withdrawals may be accompanied by uncontrolled release of Dopamine, Serotonin and other neurotransmitters. Lower GABA levels cause an increase in Norpinepherin that encourages quick emotional responses such as anger, and discourages deliberate logical thinking. High Norpinepherin causes adrenalin to be released, which can cause the heart to beat faster and harder. This also causes red corpuscle reserves to be placed in the bloodstream, which in turn causes energy sources, nutrients and oxygen to be diverted from organs and into the muscles. This is where high blood pressure occurs.

But low GABA also causes a decrease in Serotonin, which makes sleep difficult and causes depression, irritability and a lack of rational emotion. The benzodiazepine receptors are also involved in the regulation of pain perception, modulation of the immune and inflammatory systems, and the protection of cells from damage by free radicals. This helps to explain why continued use of benzodiazepines can increase pain and cause a breakdown of the immune system, while also inducing anxiety and insomnia.

Often a painkiller is added. But pain medication lowers natural Opioid levels, resulting in abnormal pain perception - causing an increase in Dopamine release that leads to anxiety. Continued Dopamine release causes emotional fatigue. Low Opioid levels also cause the lowering of GABA, which can increase anxiety, insecurity, unexplained panic and depression.  And low GABA causes a decrease in Serotonin, which makes sleep difficult and causes irritability and a lack of rational emotion. The Serotonin reduction further decreases Opioid levels, and the Stress Cycle repeats with increasing intensity. Every time one neurotransmitter is altered, it starts a chain reaction in the remaining chemicals.

Because many medications stimulate sensory nerves in the stomach, they can also cause nausea, constipation or diarrhea. Even some antibiotics act on gut receptors, causing cramps and nausea. Drugs like morphine and benzodiazepines attach to the gut’s GABA receptors and produce constipation. SSRIs work by redistributing neurotransmitters such as Serotonin and Norepenephrine, which can cause constipation or diarrhea. Therefore, a healthy stomach is essential to keep the precise balance of chemicals for optimal mental and physical health.

Various chemicals in the stomach also work to breakdown food. They include the digestive enzymes pepsin, rennin and lipase, but also the production of hydrochloric acid to establish a suitable environment for the enzymes and assist in digestion.

Often additional medications are added to stop the production of stomach acid in an attempt to ease gas, bloating and pain. But without adequate acid, the entire sequence of digestion can become compromised, since gastric acid is necessary for optimal digestion and nutrient assimilation. Hydrochloric acid is the prevalent stomach acid that is secreted naturally and is necessary to breakdown and absorb protein; activate enzymes; and for the absorption of carbohydrates, fats, vitamins and minerals. The presence of acid also assists in muscle contractions that push food through the intestines while destroying parasites, bacteria, fungi and other invaders. Without sufficient acid, microorganisms that are normally destroyed can proliferate, raising the risk of gastrointestinal infections. Additionally, the acid coming from the stomach tells the pancreas and gall bladder to pour alkaline juices in the small intestine. Without the alkaline release, a systemic acid level can build to dangerous levels, and has been associated with cardiovascular disease, diabetes and cancer. And of course, an imbalance in the stomach adversely affects the brain, resulting in increased anxiety, depression and insomnia.

The digestive tract should have 400 types of healthy bacteria that reduce the growth of harmful bacteria and promote a healthy digestive system. Antibiotics not only kill the harmful bacteria, but also destroy beneficial bacteria essential to a healthy digestive tract. This in turn impairs digestion and the assimilation of nutrients. But stress, medications, poor diet and even treated city water that contain chlorine and sodium fluoride all contribute to the breakdown of the healthy stomach bacteria. Therefore, it is important to replenish the friendly bacteria to promote good gut health.

A healthy lower intestine should contain at least 85% friendly bacteria to prevent the over colonization of microorganisms like E. coli and salmonella. Our bodies can sustain healthy states with 15% bad bacteria, but unfortunately most have the balance inverted.  The human body should have 20 times more beneficial bacteria than cells to maintain a healthy intestinal tract and help fight illness and disease.

Probiotics are carefully prepared friendly bacteria that replenish the microbial balance. Probiotics can support the immune system by protecting the body from unfriendly organisms, while preventing the overgrowth of yeast and fungus. Poor intestinal flora can contribute to depression by altering the immune system and the natural production of enzymes that assist with the absorption of nutrients. While excessive harmful bacteria byproducts can interfere with the production of neurotransmitters, beneficial bacteria eases gas, bloating, constipation and diarrhea, while supporting the production of chemicals that are inherent to life.

Good health fundamentally depends upon the friendly, symbiotic bacteria that inhabit the digestive tract and promote health. Gut health is an essential component of our general wellbeing, and Probiotics contain millions of live beneficial bacteria that bolster and replenish the microflora in the gut region.

Leave a Reply