Microbial Magic – How Fibre Fuels your Health

Our GP, Dr Vicky Carre has recently started online studies with the British Society of Lifestyle Medicine, focusing on a course exploring the gut microbiome. In this blog she explains the fascinating link between fibre and gut health, and why feeding your microbiome is so important.

We host a rainforest of over 100 trillion microorganisms in our large intestine, and our relationship with these bugs is truly symbiotic—they help us, and we help them. Collectively, these microbes possess over 150 times more genetic material than our human cells. Many of their genes encode for proteins essential for processes we rely on: digesting food, producing neurotransmitters, synthesising vitamins, and metabolising toxins. In many ways, we’ve outsourced some of our most critical biological functions to our gut bugs.

We all know that fibre is good for us and helps to ward off constipation. And we also hear about high fibre intake reducing the risk of bowel cancer, but how does it do that? The answer lies with our microbiome. Humans can’t digest fibre, so it reaches the large bowel pretty much unchanged. However, our gut bugs love it and digest it with gusto! They ferment fibre using special enzymes, producing compounds called short-chain fatty acids (SCFAs) in the process.

SCFAs serve as fuel—not just for the microbes themselves, but also for the cells lining our colon. They are also absorbed into the bloodstream and transported around the body, where they exert a wide range of beneficial effects in many organs. Research has shown that SCFAs have powerful anti-inflammatory, anti-cancer, and anti-obesity properties. In fact, maintaining a healthy gut microbiome can reduce the risk of hundreds of diseases. And the most important thing you can do to support your microbiome? Feed it well—with fibre.

You can support your microbial population numbers by eating fermented foods, drinking yoghurt with live cultures, avoiding ultra-processed foods and alcohol, only using antibiotics when strictly necessary and taking probiotic supplements —but none of these strategies will have lasting impact unless you consistently nourish your resident microbes with what they need most: fibre. You’re not just eating for yourself—you’re eating for your 100 trillion gut companions.

When it comes to fibre, think “plant-based”. That doesn’t mean going vegan (unless you want to!) —it just means loading your meals with high-fibre vegetables, fruits, and pulses whenever possible. Unlike some trendy “super-food” recommendations that can be gimmicky or expensive, high-fibre foods are easily available and affordable: onions, peas, broccoli, apples and pears (preferably with the skin on), skin-on sweet potatoes, bananas, oats, whole wheat pasta, brown rice, lentils, beans…

Dr Vicky will be sharing more about the gut microbiome over the coming weeks. In the meantime, get feeding your microbiome!