Meet the gut, your second brain

Meet the gut, your second brain.

Imagine yourself in front of a large audience, about to give a speech. As you wait for the host to call your name, you feel jittery and nervous. An odd sensation manifests deep in your gut. You can’t quite name it, the sensation, but it feels somewhat like nausea and fluttering.

That recognizable feeling is called “butterflies in the stomach”. And if you’ve ever felt it, you’re likely getting signals from an unexpected source: your “second” brain which is hidden in the walls of the digestive system- your gut.

Meet the gut, your second brain.
Meet the gut, your second brain.

What is the second brain?

Your gut is a highly innervated (having nerves) organ that possesses its nervous system known as the Enteric Nervous System (ENS).

The ENS is in regular communication with the central nervous system (CNS) through nerves such as the vagus, meaning the gut and brain are directly connected. ENS covers every part of our gut, lining our esophagus, down into our stomach, throughout our intestines large and small, and all the way to the anus.

There are hundreds of millions of neurons connecting the brain to the ENS and this vast web of connections monitors the entire digestive tract. The ENS is not conscious like our main brain (CNS) but is so extensive that it can operate independently without input from the latter.

The gut-brain connection

Remember eating all sorts of food that ended up making you feel vomity? And instinctively avoiding that food for days at the end? Your gut-brain communication is responsible for that.

The neurons, hormones, and chemical neurotransmitters combinedly send messages to the brain about the status of our gut. For the sake of simplicity, you could think of this as anytwo electric gadgets connected by a wire. These messages include information about the rate at which food is transported, the acidity of the stomach, and the amount of mucus lining the gut.

An upset stomach can send signals to the brain, just as a troubled brain can send signals to the gut. Therefore, a person’s stomach or intestinal distress can be the cause or the product of anxiety, stress, or depression, and vice versa.

Is the gut manipulating our stress level?

Our body produces about 90% serotonin, the happy chemical, in some cells in the gut. About half the amount of dopamine in our body is also produced there. Both serotonin and dopamine can influence our mood along with their physiological functions.

Since the gut makes more serotonin than the brain, neurologists are realizing the reason behind the less effectiveness of antidepressants in treating depression. These levels of serotonin can explain why emotions that we understand with the brain can be felt in the gut.

The ENS also triggers emotional shifts (like anxiety and depression) experienced by people coping with irritable bowel syndrome and problems like constipation, diarrhea, bloating, or upset stomach. Conversely, stress can also affect the movement and contractions of the gut. Complexity might arise in cases where a person experiences gastrointestinal distress with no obvious physical cause. For such disorders cannot be diagnosed and healed without considering the role of stress and emotion the person is going through.

We are more bugs than humans!

Research has shown that the body is composed of bacteria as many as our cells. Collectively these trillions of bacteria are called the microbiome. What’s more surprising is that our second brain communicates with the microbiome present in the digestive tract.

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The biomass of microbes competes within the environment in the gut, just like any ecosystem inhabited by competing species. Microbiomes are not always bad. They can play a vital role in keeping us healthy.

For a healthy gut, a rich and diverse microbiome is essential as it protects against one microbe from dominating others which could result in complications. When there is any change or shift in the composition, the functions of the microbiome are disturbed which results in inflammatory bowel diseases, bad breath, skin problems, gastrointestinal disorders, and mood shifts.

If you often crave for unhealthy food such as fries or chips, chances are you are being manipulated by your gut bacteria as they are capable of controlling our food cravings and behavior to ensure their survival.

Not only have studies shown this, but they also have begun to explore links between the disrupted gut flora, anxiety, and mood disorders. They have found that individuals who suffer from conditions like depression, Alzheimer’s disease, and related conditions that cause dementia often have gastrointestinal problems.

We are what we eat and we are what our “bugs” eat

Our gut-brain-body health is shaped from the day we are born (genetics, breastfeeding, lifestyle, environment, illness, and infection). But it’s majorly impacted by the food we eat. And what we eat isn’t nutrition just for us, it also feeds trillions of microbes that inhabit our gut.

Fortunately, we are in absolute control of every morsel of food we put in our mouth. Having a wholesome and balanced diet works wonders for everyone’s gut and brain. While it has guaranteed benefits for your waistline, it also helps you be in a better frame of mind. For instance, adding some fibers and yogurt in your meal might help you cope with the stress in a better way if you are having a hard day.

Your gut is important. Here are some food recommendations to keep it healthy

Prebiotics & Probiotics

Prebiotics are non-living, non-digestible dietary fibers that stimulate the pre-existing good bacteria in the gut and encourage the development of a diverse community of microbes. These foods are complex carbohydrates, such as vegetables and whole grains. Examples include brown rice, brown bread, potato etcetera.

Probiotics, on the flip side, are healthy live organisms present in yogurt, cheese, and other fermented foods. They have been shown to provide benefits for those suffering from inflammation and other bowel infections. Some probiotics also aid in improving symptoms of stress, anxiety, and depression.


Whole grains, pulses, nuts, seeds, fruits, and vegetables all contain prebiotic fibers that are good for your gut bacteria. They are essential for reducing inflammation & supporting healthy bowel lining. For example, it helps ease constipation and gastritis.

Omega-3 fats

These fats are found in oily fish and also in high quantities in the human brain. Omega-3s can increase good bacteria in the gut and reduce the risk of brain disorders as they maintain the dopamine levels in your brain high and are also essential for memory, language, creativity, and mood regulation.

Fermented foods

Fermented foods include kinema, gundruk, sinki , sauerkraut, yogurt, and many pickles. These foods contain all healthy microbes which have been shown to alter brain activity, improve digestion, boost immunity, and help in the synthesis of some vitamins.

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Amino acids

They are essential building blocks of protein, especially tryptophan, a key amino acid that can be converted into several important molecules, including serotonin and melatonin, necessary for regulation of mood, sleep, and behavior. Foods that are high in tryptophan include fish, lentils, pumpkin and sesame seeds, eggs, and peanuts.


Cocoa, green tea, olive oil, and coffee all contain polyphenols, which are plant chemicals that are digested by your gut bacteria. Polyphenols enhance healthy gut bacteria and may improve cognition by inhibiting the growth of pathogens, thus exert prebiotic-like effects. They also have the potential to improve depression because of their anti-inflammatory and antioxidant effects.

Herbs and spices

Spices like turmeric, garlic, onion, fenugreek, cloves, peppermint can act as anti-inflammatory, antioxidant, antispasmodic, antimicrobial effects which also aid in improving cognition, focus and may act as an antidepressant.

End thoughts

To maintain a fit gut-brain health, we also need to focus on our sleep as our mental health is closely linked to its quality and timing. An unbalanced gut may invite sleep problems and lead to a range of health issues, such as obesity, metabolic and inflammatory disease, and mood disorders.

Also, antibiotics should be avoided in redundant cases as they inhibit the growth of microbiomes and destroy them. If antibiotics are overused, harmful bacteria can become resistant to them, making the antibiotic less effective in further usage.

The gut is a strange, complex, and intricate system that plays a much larger role in the way you think, feel, and act. Now, knowing that you have an additional brain entwined in your belly, the next time you feel jittery down there, eat some yogurt and make your microbiome happy.



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Arju Palikhey is a second-year undergraduate student of Nutrition and Dietetics at Central Campus of Technology, Dharan.

Arju PalikheyArju Palikhey

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Arju Palikhey

An undergrad student of B.Sc. Nutrition and Dietetics.
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