In a lab in Ireland, a group of scientists stand around a stainless steel table. One of them is holding a device, not unlike a small turkey baster. His free hand plunges into a box on the table and retrieves a mouse.

Using his device, he administers the brown solution within…rectally.

This unfortunate soul has just received a fecal microbiota transplant. The donor was not another mouse but a human being. And the person in question had symptoms of severe depression.

Jonathan speaks to John Cryan, author of the study that showed a relationship between gut and brain. In this episode, we learn more about his fascinating research, how microbes may affect our brain, and to eat to appease your gut bugs.

John Cryan is a professor at University College Cork and a world-leading researcher into the relationship between our brain and our gut microbiome.

Download our FREE guide — Top 10 Tips to Live Healthier: https://zoe.com/freeguide

Timecodes:

00:00 - Introduction

02:05 - Quickfire questions

03:26 - Are there links between the gut and the brain?

06:31 - The gut-brain axis

09:17 - How do gut bacteria affect our brains?

11:12 - Why does John call the microbiome “the chamber of secrets”?

14:20 - Does the microbiome explain drug side effects?

15:51 - Are there links between our microbiomes and mental health?

20:40 - If we improve our microbiome health can we improve our mental health?

24:58 - Can food help improve the microbiome and thus improve mental health?

28:33 - Microbiome’s effect on behavior

29:54 - Actionable advice

34:43 - Microbiome in adolescence

37:18 - Summary

38:26 - Goodbyes

38:48 - Outro

Episode transcripts are available here.

Follow John: https://twitter.com/jfcryan

Follow ZOE on Instagram: https://www.instagram.com/zoe/

This podcast was produced by Fascinate Productions.

HOT TOPICS | Signalgate Scandal... What Scandal? - March 27th, 2025