Diet your way to a healthy gut microbiome

Our guts are inhabited by tens of trillions of microorganisms – bacteria, yeasts and even viruses – that are collectively referred to as our gut microbiome. Recent advances in science have shown that the composition of our microbiome has a direct correlation to our physical and mental health, immunity, susceptibility to disease, and much more.

Any changes in the composition of our microbiome can wreak havoc on the body, with the biggest factor affecting us being the kind and quality of food we eat. Other factors such as age, disease, medication, and chemicals we ingest, and even the levels of stress we are under, can alter the composition of our gut flora.

Maintaining a healthy gut then would mean harbouring a variety of gut microbes – of which there are an estimated 1,000 species – and ensuring their individual and combined populations are stable. Moreover, scientists have found that eating certain types of food and making small modifications to our lifestyle can keep the gut healthy.

Ayurveda too confers with this view. While it doesn’t define the gut microbiome, ayurveda does suggest that all health is linked with the gut through ‘Agni’ or the core digestive fire within one’s body. It even speaks of ‘Ojas’, a product of healthy digestion that strengthens the immune system and has many beneficial effects for the body and mind.

Here are a few research-backed ways in which we can ensure a healthy microbiome inside us:

Maintain a diverse diet

Our guts are home to hundreds of different species of microbes, each capable of transforming energy from the food we eat into different molecules. Research in animal as well as human models has shown to some extent that the more diverse our diet, the more diverse is the make-up of out gut microbiome.

There could be several reasons to explain this, but most scientists believe that a diverse diet provides food and a substrate to the various organisms in our guts. These organisms can then do their job of producing various molecules such as short-chain fatty acids or neurotransmitters that determine our health.

Interestingly, it has been observed that infants have a more diverse microbiome than adults, possibly as they transition from liquid diet to solid foods, where there is a lot of experimentation to figure out what a child likes before settling on a relatively fixed diet.

Adults, on the other hand, especially given the prevalence of ‘Western diet’, tend to consume similar foods and hence have a less diverse microbiome.

Studies comparing the microbiomes of people living in different regions of India found some evidence that those living in low-lying rural regions had the greatest microbial diversity. Moreover, the gut microbiome make-up deferred based on animal versus plant diet, rural versus urban, and factors such as pollution, etc.

Now what may constitute a healthy diet? If Ayurveda is considered, a balanced diet is one that includes foods of all six tastes – sweet, sour, salty, bitter, spicy and astringent. This is key to a healthy gut. It suggests a poor diet would include food combinations containing fried foods, highly processed foods, excessive sweet, salty and sour tasting foods, or an excess of cold or raw foods.

Take probiotics and prebiotics

Probiotics are live organisms – yeasts and bacteria – which when eaten deliver health benefits to the host. Studies have found that the intake of probiotics, specifically yoghurt and other fermented foods, can restore the composition of the gut microbiome when used in a sustained manner.

Microbes in the gut convert nutrients from our diet to metabolites that affect several regulatory functions in the host. Consumption of probiotics has been linked with improved gut microbe diversity, reduced inflammation of the gut and reduction in the risk of developing several diseases.

Prebiotics for their part are usually non-digestible components of our food – such as fibre. They serve as food for intestinal microbes and encourage their growth. Eating a diet rich in fibre has been linked with a healthier gut microbiome that promotes healthy ageing and keeps metabolic and heart-related disorders at bay.

Studies have also shown that certain prebiotics can maintain healthy insulin and cholesterol levels in obese individuals, who would otherwise be prone to metabolic and heart problems.

These foods, which are a staple in many cultures, finds mention in Ayurvedic texts as well. Curd, one of the most widely eaten fermented foods in India, is defined in the Charaka Samhita, an ancient ayurvedic text as “an appetiser, digestive stimulant, unctuous, strength promoting and alleviator of vata, auspicious and nourishing.”

Cut processed foods

While it is abundantly clear that diet can have an outsized effect on the human microbiome, recent studies have shown that diet changes can lead to large changes in the microbiome in a span of just 24 hours. Moreover, western diets that are generally high in protein and fats but low in fibre have been linked with a marked decrease in total bacteria, including beneficial species.

Processed foods are also high in saturated and trans fats while being low in mono and polyunsaturated fats, which have been known to lower diversity of gut microbes. These are also linked with an increase in body mass index (BMI) that is linked with increased incidence of metabolic and other diseases.

Moreover, processed foods also contain high amounts of refined sugars and low levels of plant fibres. Experts say these foods provide excess energy and little to no nutrition to the hosts as well as the microbes residing in their guts. This is also directly linked with higher amounts of endotoxins that are created when bacteria in the gut die and can pass through the gastro-intestinal barrier and end up in the bloodstream.

Ayurveda too advises against consuming heavy, greasy, and mucus-forming foods, which it says could help to heal the gut and reboot the microbiome.

Limit antibiotics

Several studies have shown that the use of antibiotics can result in changes in the composition of gut microbiota; sustained or heavy dosage of such medications can often result in reduced microbial diversity in the gut. This can linger for a long time, with some studies suggesting that it may never come back to its old state.

Broad-spectrum antibiotics do not just reduce the population of individual strains of microbes, but also reduce their diversity. Beyond this, antibiotics can also alter the gene expression, protein activity and metabolism of the microbes in the gut. Scientists have found that these microbes more closely resemble those under disease conditions.

Another source of antibiotics for us humans is also the food that has been treated with antibiotics. While this constitutes as low-dosage intake of antibiotics, its effects can add up over time and show up in our body in a similar way to antibiotic overuse.

The bottom line

There are various factors that affect our gut microbiome, but none is more important than the food that we eat. Eating a balanced diet can ensure that our microbiome works optimally, which can in turn reduce our risk of developing chronic diseases that have now been linked with dysbiosis of the gut.