Eat, feel, think: The gut-brain axis

Healthy lifestyle (representative image)

In August 2023, a Russian influencer living in Malaysia, died unexpectedly. She was 39. Zhana Samsonova propagated a vegan-only diet to her 600,000 followers on social media. Her friend and neighbour stated the cause as reportedly being from starvation.

A month prior, German fitness influencer Jo Lindner, succumbed to a bulging artery. Three days prior to his death, he’d complained of pain in the neck. Lindner would post on his diet, his exercise routines and pictures of his unbelievably chiseled body for his nine million followers on Instagram. He’d had a hernia operation and had undergone Testosterone Replacement Therapy (TRT). He was 30.

Over the past few years, cases of unexpected death among young people following extreme diets or exercise regimes have been reported worldwide. Mishti Mukherjee, an Indian actress died at 27 of kidney failure. She’d been reportedly following a strict Keto diet, high in protein, for longer than the stipulated time, known to put pressure on the liver and kidneys. A 21-year-old Chinese influencer who targeted shedding over 50 pounds in two months died reportedly of extreme diet and exercise routines.

Unhealthy and unrealistic trends promoting extreme weight loss and exercise routines have led to chronic fatigue and exhaustion, imbalance in critical nutrients, electrolytes and biochemicals, pressure on and damage to vital organs, and death, even. Samsonova’s extreme all-vegan diet of jackfruit, durian and no water, would have led to critical drops in levels of B complex, vitamin D, calcium and iron among several other minerals and nutrients the body requires to function on.

The key word here is ‘extreme’. But, under a barrage of diverse and often experimental diet opinions on social media, what is the line to take and where does it end? Is there a correct diet to follow?

Researchers at the University of Cork, Ireland, put together a specific diet and observed results within a trial group over four weeks. They found a spike in good bacteria in the gut of participants who followed the diet. They also found a significant reduction in stress in these adults. The diet consisted of whole grains, legumes, fermented foods, fruits and vegetables that are rich in fibres and nutrients through the day – pretty much a normal, traditional diet across swathes of the globe.

There are two points to note from this study. The first is the food itself. For all the rigmarole on special diets, the emphasis on a fresh, diverse meal in line with family or cultural traditions seems most balanced and suited to each individual. These are the ones many of us in our forties and fifties have eaten as children. As we grow older, it is more the portions that we may wish to reduce, rather than to make any drastic changes in what we are eating. Timings are important as well – eating around fixed hours and finishing dinner early – that matter, in maintaining the right balance between health and weight, apart from a light but regular exercise routine.

The second point of note in the study above, is the reduction in stress, through food. In what has come to be known as the “microbiota gut-brain axis”, scientists are increasingly beginning to mark the effects of a direct connection between food and emotion.

In a supporting experiment, germ-free mice from a sterile environment, were fed with a probiotic, that led to an increase in good bacteria in their abdominal tract. They noted the mice were markedly less reactive to stress, anxiety and depression.

Research into gut-brain imaging studies reveal how this largely works.

On estimate, humans have roughly 100 trillion microbes in the gut spread across a few thousand species. (The human body in comparison has around 30 trillion human cells). The food we eat influences the bacteria and microbiome in the gut. Good bacteria, through a balanced diet, generate chemicals which leads to better absorption and digestion, which, in turn, determines our energy levels. The abdomen is often referred to as the engine of the body. But apart from how sprightly we feel, or how much stamina we have, the gut-brain axis seems to influence how we experience sensation and emotion.

We know that the gut is susceptible to mood. When we are stressed or anxious, the gut is affected first. People who think too much often have a weak stomach. Additionally, through that strong ‘gut feeling’, we sense the working of stress and fear consciously in the gut, even before the brain actively may have noted it. With its 500 million neurons, the gut is super sensitive at registering and responding to certain emotions.

But the gut-brain axis microbiota lays an equal focus on the gut as a driving agent, rather than a receptor, for what we sense and how we feel. The gut is an important contributor to the production of important neurotransmitters, especially serotonin and gamma-aminobutryric acid (GABA). Serotonin contributes to our feeling of wellness, as well as aids the functioning of the body clock. 95% of body serotonin is produced by gut microbiome. GABA, largely produced by microbiota in the abdominal tract, helps in controlling feelings of anxiety and fear. It puts the brakes on these feelings.

Changes in the level of GABA have been linked to depression, anxiety, schizophrenia and autism. Good bacteria, specifically lactic acid bacillus, contributes to the generation of biochemicals, which, as now we know, directly affect mood.

If the gut is in good shape, that’s the signal relayed and picked up by the brain, as well.

Such communication between the brain and gut is aided by a network of cranial nerves. The longest of these is the Vagus nerve, originating from the brainstem which goes on to service organs of the chest and abdomen. It carries messages both ways, signaling changes in these areas to the brain and vice versa.

Taking off from here, scientists are observing, reporting and experimenting on how shifting microbes in the gut can directly alter and influence our emotional and mental health. In a new field called Psycho-biotics, the emphasis is to find the means to treat and alleviate depression and anxiety through changes in our diet, rather than on medication alone.

Interestingly, the idea that good gut bacteria can alleviate symptoms of melancholia was first propagated by JPG Phillips in 1910. It has taken a century for scientists to piece together the fact that the gut-brain axis is a critical pathway to the treatment and prevention of clinical depression, among other mood disorders.

While science gathers further evidence on this approach, here are a few take aways to consider – a balanced diet (the one our grandparents ate) is good for the body; fasting once a week (as Rishi Sunak does!) gives the gut a chance to catch up and/or rest; portions are critical. Small portions through the day, or to quit eating before we hit the full button, helps the gut digest the food better and more efficiently. Meal timings matter as much as what we eat. Diets may be tried out, but for short, stipulated windows of time.

Finally, the corollary to “we are what we think”, and “we are what we eat”, may well be, at the end, “what we eat is how we feel. And think.”

This article is authored by Vandana Kohli, entrepreneur, filmmaker and author, New Delhi.

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