The Gut Brain Connection Basics

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Have you ever gone through this? You missed a deadline, or you have an upcoming Math test, and you feel a clenching in your gut, simply put, “Butterflies in the stomach” or “Gut Feeling”. What makes the gut sensitive to situations or emotions that we feel?  In this article we discuss the gut brain connection and how can we take care of our gut and mental health.

What Is The Gut Brain Connection?

The signaling between the brain and intestine is known as the Gut-Brain Axis (GBA). The digestive system has its own nervous system, called the enteric nervous system (ENS). It has over 100 million nerve endings, it controls digestion independently without your conscious awareness. The ENS is called the “Second Brain.” This gut-brain is connected to our “big brain” via a network of nerve pathways and the two nervous systems share many of the same neurotransmitters to facilitate communication. GBA involves moment-to-moment communication to control digestion. This explains why your stomach may start growling at the sight of a juicy steak before the food even hits the stomach or when you are under stress. ENS in the gastrointestinal (GI) tract regulates digestion (Carabotti et al, 2015). Bacteria in the gut produce neurotransmitters and short-chain fatty acids that stimulate the nervous system. This nervous system regulates mental health.

Diversity In The Gut Microbiome Is An Indicator Of Mental Health

The gut microbiome is made up of trillions of bacteria. Studies indicate that certain bacteria enhance memory and regulate stress. In recent years, there has  been increasing interest in the study of psychobiotics, specific bacteria that have mental health benefits when ingested, and the practice of fecal transplants. Neurons in the gut release (GI) Hormones.

Neuroendocrine signaling occurs when bacteria in the gut trigger enteroendocrine cells in the lining of the intestinal wall. The cells release neuropeptides like cholecystokinin which is a satiety (feeling of fullness!) hormone (Hirokazu et al, 2018). More than 90% of serotonin (the happiness hormone!) is made in the gut. The microbial diversity in decreases with increasing age. Stress, in particular, has a significant  impact on the microbiota-gut-brain axis at all stages of life.

Individuals with a chronic digestive condition, such as irritable bowel syndrome (IBS) or inflammatory bowel disease (Crohn's disease, ulcerative colitis) are very sensitive to stress. Seventy percent of patients with Crohn's disease and ulcerative colitis believe that flare-ups of their disease are related to stressful events. Experiments on animal models confirmed that stress caused inflammation in the gut.

Studies provide evidence that the gut microbiome has a  role to play in conditions including autism, anxiety, obesity, schizophrenia, Parkinson’s disease, and Alzheimer’s disease. Much of the earlier work regarding gut-brain communication concentrated on digestive function and satiety, but recent research has taken an increasing focus on higher-order cognitive and psychological effects of gut-to-brain and brain-to-gut communication.

Diet affects your mood and your mood affects your digestion. How gut microbes control digestion we still don’t fully understand this yet, but food is at the center of who we are. The interaction of vagal neurons, gut bacteria, and neuropeptide hormones contributes to brain activity and gut health. Scientists are investigating ways to promote healthy communication between the gut and the brain, as well as identify what hinders their relationship.

How Are Stress And IBS Related?

In an atypical science story around the year 1822, a fur trader named St. Martin was accidentally shot at close range, during his treatment by the United States Army surgeon William Beaumont, he became one of the most famous patients in gastroenterology. The surgery left St. Martin with a fistula in his gut, a window into the intestine, for Beaumont to study. The doctor took careful notes throughout the recovery period and discovered the manner in which many aspects of digestion occurred. He sent gastric secretion samples to chemists for analysis. This was one of the first recorded observations of human digestion taking place in real time. Beaumont made notes on “pain and uneasiness” at sites far from the wound. Moreover, when St. Martin became angry or irritable, it greatly affected the rate of digestion. This meant that digestion, and emotional state were interlinked. Beaumont became the pioneer to an era of precise clinical data collection, observation, and recording of conclusions for further study. 

To further understand the link between stress and the gut we need to look at the autonomic nervous system (ANS). The ANS is made up of sympathetic and parasympathetic nervous systems. The sympathetic nervous system is responsible for the ‘Flight or Fight’ responses of the body in conditions of stress or sudden shock while the parasympathetic nervous system is responsible to exert a calming effect on the body.

The vagus nerve runs from the brain to the stomach and represents the main component of the parasympathetic nervous system. The vagus nerve is the longest nerve of the body and it branches throughout all the main organs in the body.  This nerve oversees a vast array of crucial body functions, including control of mood, immune response, digestion, and heart rate. Some research suggests stress can inhibit the vagus nerve from functioning optimally. Other research has focused on vagus nerve stimulation to support mental health conditions.

Treatment Of Digestive Ailments With Integrative Medicine

The gut-brain axis highlights the importance of good nutrition when it comes to good health.  Having a healthy diet will help support a healthy, balanced gut ecosystem and in turn, support the gut-brain axis and mental health. Certain food groups help improve mental health include omega-3, high fiber foods, foods rich in polyphenols such as olive oil, green tea, cocoa. Foods like eggs, cheese and turkey are rich in the amino acid tryptophan are converted into serotonin. Serotonin is responsible to for good mood.  Other nutrients that are proving key to good mental health include iron, vitamin D, B vitamins particularly B12 and B9 (folate), zinc, and magnesium.

gut brain connection

Include Prebiotics And Probiotics For Better Gut Health

Prebiotics are substrates that are selectively utilized by host microorganisms conferring a health benefit. Examples include fruits and vegetables such as asparagus, leek, banana, chicory, and grains such as oats and wheat. Probiotics are live bacteria which when ingested in adequate amounts, confer health benefits. Through interacting with the host microbiota and intestinal epithelium, probiotics have been shown to exert a wide range of effects upon host health, with various strains improving metabolism, immunity, endocrine function, and slowing aging in preclinical studies. Indeed, certain bacterial strains or cocktails of multiple bacteria have demonstrated efficacy in improving behavioral symptoms of various disorders from depression and anxiety to autism.

Apart from this, avoid caffeine which can amplify nervousness, anxiety and bowel discomfort. Try swapping your coffee for herbal teas that have less caffeine and drink plenty of water.

Some healthcare professionals support patients with gastrointestinal disorders with stress reduction techniques to manage symptoms. This can include using psychological therapies alone, or alongside other treatments.

Cognitive Behavioral Therapy (CBT)

A therapy in which the therapist talks and looks at the links between your thoughts, feelings, physical symptoms and behavior.

Relaxation Therapy

In this therapy , the focus is on vagal tone improvement and the GBA. This is achieved by stimulation of Vagus nerve by deep breathing exercises.

Meditation, singing, humming, chanting “om” and physical activity have also been found to improve vagal tone and the GBA.

Medical Hypnotherapy Specific To The Gastrointestinal System

In conclusion we can say that the gut-brain axis intricately connects the gut and the brain, thus affecting important functions of the body. It is a relatively new field of science and one that researchers are still understanding. [3] The awareness about GBA, factors affecting our immunity, digestion and mental health will help us make more informed decisions and help in living a healthy life.


[4] How Your Brain and Emotions Control Your Gut and Cause Pain (

Rosemary Richards