Why Modern Life is Keeping Our Immune System Switched On with Will Bulsiewicz, MD | MGC Ep. 108

In this episode of The Mind–Gut Conversation, Dr. Emeran Mayer sits down with Will Bulsiewicz, board-certified gastroenterologist, New York Times bestselling author, and one of today’s leading voices in microbiome science.

Drawing from his newest book, Plant-Powered Plus, Dr. Bulsiewicz explores why chronic, low-grade immune activation has become so widespread—and how modern lifestyles are keeping our immune system permanently switched on.

Together, they examine the deep connections between diet, the microbiome, the immune system, and inflammation, unpacking how evolutionary mismatches, ultra-processed foods, low fiber intake, chronic stress, and social disconnection are reshaping human health. The conversation moves beyond symptoms to address root causes, highlighting why restoring health requires rethinking how we eat, live, and connect.

This wide-ranging discussion blends cutting-edge science with clinical insight, offering a grounded, practical perspective on how small, sustainable changes can meaningfully reduce inflammation and support long-term well-being.

Topics discussed include:

• What inflammation really is—and why it’s no longer just an acute response

• How the gut microbiome and immune system interact

• The role of fiber, polyphenols, and microbial metabolites in regulating inflammation

• Why modern environments clash with human biology

• How lifestyle factors like stress, loneliness, and purpose influence immune health

This is a practical, evidence-based discussion for anyone seeking to understand how modern lifestyle factors shape immune health, inflammation, and long-term well-being.

Please leave any comments or feedback on the episode — we’d love to hear your thoughts.

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This episode is brought to you by Mayer Nutrition. If you are interested in trying Synaptic Bloom, our high-potency Quercetin + supporting polyphenols blend, you can visit mayernutrition.com, and use our exclusive podcast discount code: MINDGUT for 10% off your first order!

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Connect with Dr. Mayer:

Website: https://www.emeranmayer.com

Instagram: https://www.instagram.com/emeranmayer/

X (Twitter): https://www.twitter.com/emeranmayermd

Facebook: https://www.facebook.com/EmeranMayerMD/

LinkedIn: https://www.linkedin.com/in/emeranmayer/

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Chapters:

0:00 – Introduction

3:00 – Purpose, Medicine, and the Evolution of Gut Health

7:00 – What Inflammation Really Is

12:30 – Modern Life and the Immune System

18:00 – The Gut Microbiome and Immune Activation

26:00 – Diet, Fiber, and Microbial Health

38:21 – Mayer Nutrition

40:15 – Lifestyle, Stress, and Social Connection

49:00 – Technology, Medicine, and the Future of Health

1:05:00 – Practical Takeaways and Closing Reflections