Fiber: the essential gut nutrient

Heart disease, dementia, depression, diabetes: what do these conditions have in common? Dr Will Bulsiewicz, a gastroenterologist and New York Times bestselling author, says the answer is inflammation. In today’s episode, Will explains the four nutrition workhorses that can reduce inflammation, heal your gut and supercharge your immune system - in as little as 24 hours.

We explore discoveries in Will’s new book, Plant Powered Plus, that explain the central role inflammation plays in health. You’ll learn which symptoms that seem unrelated, such as fatigue, skin breakouts, bloating, headaches, and joint pain, all share a common driver. You’ll also hear why he believes the gut and the immune system rise and fall together, and how a weakened gut barrier may keep the immune system on constant alert.

By the end of the episode, you will have a clear understanding of what inflammation is, how it can cause damage, and practical, food-first ideas to wrestle yourself from its clutches.

What’s one small change you could try this week? In your meals or your routine to help your body switch off “fight mode”?

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Timecodes

00:00 Intro

02:22 Is inflammation always bad?

05:00 The 130 health conditions linked to inflammation

08:40 The difference between good and bad inflammation

10:50 Surprising signs of chronic inflammation you might ignore

13:40 Why your doctor might be missing the root cause of your illness

17:50 Why you shouldn't take anti-inflammatory pills every day

19:55 70% of your immune system lives here

23:30 What is ‘leaky gut’ and does it really exist?

25:20 How toxins sneak into your bloodstream

31:35 The massive impact of time-restricted eating on mood and energy

37:30 Why eating earlier in the day reduces inflammation

41:05 The #1 nutrient deficiency destroying our gut health

44:10 How fiber protects against heart disease and cancer

47:30 Why you need to ‘eat the rainbow’ to find your pot of gold

51:35 Your body can’t absorb these nutrients without microbes

52:50 The truth about healthy fats versus low-fat diets

55:05 The specific fat that beats a low-fat diet for heart health

58:00 How fermented foods reduce inflammation in just 10 weeks

01:00:35 The physical reaction your gut has to mental stress

01:06:25 The modern lifestyle mistake sabotaging your immune system

01:08:35 The simple morning habit that boosts energy and sleep

01:10:45 You can build a new gut barrier in just 5 days

📚Books by our ZOE Scientists

The Food For Life Cookbook

Every Body Should Know This by Dr Federica Amati

Food For Life by Prof. Tim Spector

Ferment by Prof. Tim Spector

Free resources from ZOE

How to eat in 2026 - Discover ZOE’s 8 nutrition principles for long-term health

Live Healthier: Top 10 Tips From ZOE Science & Nutrition

Gut Guide - For a Healthier Microbiome in Weeks 

Better Breakfast Guide

Mentioned in today's episode

• Plant Powered Plus by Dr Will Bulsiewicz
• Fibre Fuelled by Dr Will Bulsiewicz
• ZOE’s PREDICT studies: What we’ve learned 
• The Detrimental Impact of Ultra-Processed Foods on the Human Gut Microbiome and Gut Barrier, Nutrients (2025)
• Correlation between human gut microbiome and diseases, Infectious Medicine (2020)
• The ZOE BIG IF Study, MDPI (2024)
• Dietary fibre in hypertension and cardiovascular disease management, BioMed Central (2022)
• PREDIMED: Primary Prevention of Cardiovascular Disease with a Mediterranean Diet, The Journal of New England Medicine (2018)
• Gut-microbiota-targeted diets modulate human immune status, Cell (2021)
• Gastrointestinal illness and the biopsychosocial model, Psychosomatic Medicine (1998)

Have feedback or a topic you'd like us to cover? Let us know here.
Episode transcripts are available here.