Could the food you ate yesterday already be reshaping your gut, your immune system and your risk of chronic disease? This week’s guest says yes, and he’s spent his career demonstrating why that matters so much.

Dr Will Bulsiewicz is an award-winning gastroenterologist and the author of the new book, Plant Powered Plus. And few people can explain the science of gut health as clearly, or as compassionately, as Will does in this conversation. If you think you already know everything there is to know about digestion, fibre and plant foods, this episode will change your mind – and deliver a great deal more.

Will has identified four nutrition ‘workhorses’ that feed and protect our guts and, unsurprisingly, fibre is one of them. We get into the specifics of how the fibre we eat turns into short-chain fatty acids like butyrate, which Will describes as the most anti-inflammatory substance he has ever come across. He makes the case for fibre as the true longevity nutrient. We talk about resistant starch, found in cooled potatoes and green bananas, and why it feeds a completely different part of your gut microbiome to other fibres. Will shares the research behind the ‘30 plants a week’ target, and why he thinks the exact figure matters far less than most people assume. And he covers the importance of polyphenols, healthy fats and fermented foods.

There’s a fascinating section on the different ways our gut microbiomes are shaped by our closest relationships, including some research findings even Will found surprising. We bust some myths around the term ‘leaky gut’. And we discuss why he no longer sees Crohn’s disease and ulcerative colitis as straightforward autoimmune conditions, but more like the immune system turning against the microbiome.

Will is refreshingly honest about the limits of diet alone. He talks candidly about the patients he could not help through nutrition or medication, and about a period in his own life when food became a coping mechanism for something he wasn’t able to face. It is a reminder that lasting health often asks more of us than simply eating better.

Whether you’re new to the topic of gut health or well acquainted, this episode brings a new perspective. It’s packed with valuable and actionable moments – and it’s one you’ll come back to again and again.