An expert guide to gut health

Trillions of bacteria live inside our gut and compose our gut microbiome. Compelling evidence from extensive research over the past decade shows that the bacteria in our gut affect everything, from our digestion to our mental health.

“Every person has a unique gut microbiome, just like your fingerprint,” says Dr Kalpana Devalia, a consultant bariatric and gastrointestinal surgeon at Cleveland Clinic London. “Having a healthy gut essentially means that we have healthy microbes in our gut microbiome, which is beneficial for our overall health.

“What we eat affects our gut microbiome, so when we change what we eat, it changes our gut microbiome composition. Some common symptoms of people with poor gut health are heartburn, gas and bloating, and constipation. A good balance of healthy microbes is therefore essential to help prevent chronic digestive problems. In addition to digestive symptoms, other symptoms that could be manifestations of an unhealthy gut microbiome include poor sleep, skin rashes, sugar cravings, and some mood disorders.”

Dr Kalpana Devalia of Cleveland Clinic London

Beneficial foods
Dr Devalia shares a few simple ways to improve the gut microbiome, such as increasing the intake of wholegrain plant-based foods, eating more fibre from fruits and vegetables, and significantly reducing the intake of ultra-processed foods.

As a simple guide to a well-balanced diet, about a third should constitute a variety of colourful fruits and vegetables, another third should be composed of starchy carbohydrates – essentially high-fibre wholegrain options – and the final third should be lean protein-rich foods, such as poultry, fish, legumes and dairy.

Prebiotics – plant-based fibre contained in foods – can also stimulate the growth of healthy bacteria inside the intestine. Foods that are rich in prebiotics include onions, garlic, nuts and seeds, fruits, vegetables, beans, lentils and chickpeas.

There is also compelling evidence to suggest that probiotic foods – foods packed with healthy live bacteria or yeasts – promote a healthy microbiome. These include fermented foods, such as certain pickles and yoghurt, kimchi and sauerkraut, as well as drinks such as kefir and kombucha.

Foods to limit or avoid
Several foods can cause digestive issues and should be avoided or at least limited, advises Dr Devalia. These include ultra-processed fast foods that can slow digestion and lead to bloating. In addition, foods that contain preservatives can slow down digestive motility and allow bad bacteria build-up.

The food types to limit include fried food, since oils laden with saturated fats can lead to indigestion, gas and diarrhoea, and refined sugars and artificial sweeteners, which can be difficult for the body to process. Excessive alcohol and caffeine consumption can also cause digestive issues and contribute to chronic inflammation.

Dr Devalia also advises limiting the consumption of red meat, since research has shown that red meat is associated with an increased risk of heart disease and cancer. For individuals with high cholesterol or heart disease, it is recommended to eat 85g or less per week.

Impact of gut health on metabolism
Extensive research over the past two decades has highlighted the effect of the gut microbiome on body weight and metabolism.

“Regulation of body weight is extremely complex and is not as simple as calories in and calories out,” explains Dr Devalia. “We now know that the gut plays a crucial role in weight management and metabolism, as well as influencing the risk of developing certain chronic diseases such as obesity, diabetes, cardiovascular diseases, some autoimmune conditions and even certain cancers.”

Research is ongoing on how the gut microbiome works in tandem with the brain, and also influences our metabolism. “We have the power to improve our overall health and general wellbeing by eating healthy foods, a microbiome-friendly diet, and adopting a healthy lifestyle that includes stress management and regular exercise,” concludes Dr Devalia.