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Do You Know About Brain-Gut Connection?
  • Arati Shah

  • 17, Oct. 2019

Do You Know About Brain-Gut Connection?

Very often in life we tend to use statements like “l feel butterflies in my stomach” or ‘What a gut-wrenching experience!’ At times we would have felt ourstomach in knots” too. Are you aware that these expressions in fact do have a scientific basis? The human gut is sensitive to emotions like anxiety, fear, joy and sadness. Emotions create physiological changes in the body, including in the gut - the stomach and intestines.There is a strong communication between the gut and the brain, where one’s health affects the other. This communication is called gut-brain axis. Both the organs are connected physically as well as biochemically. The vagus nerve is one of the biggest nerves connecting both the brain and gut, in both the directions. Visiting a clinical nutritionist can help one understand how this connection works. This gut brain connection also explains how overeating leads to obesity which is important for those on weight loss programs to understand. 

So what is the gut? 

Gut is nothing but the gastrointestinal tract or GI tract. It is basically every organ that is involved in the digestion and absorption of food, from the mouth to intestines. The lining of the GI tract or gut is informally referred to as the ‘second brain’. This brain is called as “Enteric Nervous System”. 

What’s the connection between the gut and the brain? 

1. Mood changes and gut health: 

The brain has a direct impact on GI tract. For e.g., a distressed gut can send signals to brain and likewise a distressed brain can send signals to the gut. How does this happen? The gut and the brain are connected via the chemicals called neurotransmitters. Some neurotransmitters are produced in the brain whereas many are produced by the gut cells and the microbes in the gut. For example the neurotransmitter‘serotonin’ produced by the brain plays a role insleep, appetite and feeling happy while the neurotransmitter Gamma-AminoButyric Acid (GABA)which helps control feelings of fear and anxiety is produced by gut cells and microbes. 95% of the serotonin receptors arestored in the gut.Gut bacteria also produce other neurotransmitters like dopamine, norepinephrine, etc which have a role to play in moods, anxiety, concentration, etc. The gut microbiome can cause a change in how the brain reacts. Thus dysbiosis, an imbalance of the good and the bad gut bacteria can cause a change in the moods of an individual.  

2. Effect on digestion: 

The biochemical and hormonal changes occurring in response to emotional stress have an impact on digestive health, both immediate and long term. So, gastric disturbances like constipation, diarrhea, flatulence, bloating, pain and stomach upset could be a result of stress or depression in cases of unknown physical cause. Similarly, irritation in the GI system might send signals to the brain that trigger mood changes. The enteric nervous system’s response to fight or flight response is to either stop digestion, slow it down or speed up the process and hence can lead to GI disorders. Serotonin is a hunger suppressant neurotransmitterand hence reduces appetite leading to prevention of over eating. Gut microbes also produces Short Chain Fatty Acids (butyrate, propionate and acetate) which are also responsible in reducing appetite. So, a healthy mind ensures healthy gut which in turn ensures healthy microbiome in the gut.  

3. Effect on sleep: 

There is some evidence that suggests that the gut microbiota can have an influence on sleep quality and the circadian rhythm. And, our mental health has a close link with the timing and quality of our sleep. Disruptions in our circadian rhythm leads to health issues like obesity, mood disorders, metabolic and inflammatory disease, etc.  

A good diet affects both, the mental health and the gut microbiota. A healthy gut microbiome is linked to brain health. There are certain foods that play a positive role in the gut – brain axis. 

High fiber foods: Prebiotic fiber is present in fruits, vegetables, nuts, grains and seeds that are food for the gut microbes. 

Fermented foods: Fermented foods like kefir, curd, cheese, kimchi, idlis, etc contain the healthy bacteria, lactic acid bacteria.  

Omega 3 fats: Some studies do indicate that omega 3 fats found in fish as well as from plant sources like walnuts and flaxseeds do play a role in increasing the good gut bacteria. 

Foods rich in tryptophan: Tryptophan can be converted into serotonin and so foods that are high in tryptophan like eggs, cheese, etc should be included in the diet. 
Foods rich in polyphenols: Polyphenols from foods like green tea, olive oil, cocoa, and coffee are plant chemicals that are food for your gut bacteria.  

Throughout life, various changes occur in the microbial diversity of humans. Though the gut microbiota can be markedly affected by genetics, lifestyle, medications, health status, etc, diet remains the most important factor that affects the gut microbiota thus affecting the gut brain axis. There definitely exists a gut-brain connection which has an effect on mood changes, digestion, neurotransmitter generation and health. So, by alternating the microbiome of the gut, it might be possible to improve and have a positive impact on brain health too. For understanding on how to improve the microbiome of the gut, a clinical nutritionist can help plan a balanced diet for it. Those on weight loss programs also understand the need to eat a healthy balanced diet for the gut to aid in the weight loss process.