How you can eat to beat stress with a gut-friendly diet

New research from UCC's APC Microbiome Ireland indicates that eating a diet rich in fiber, fermented foods and wholegrains may help with perceived stress level 

Prof John F Cryan and Prof Ted Dinan coined the term ‘psychobiotic diet’ almost a decade ago: “It’s a way of describing eating for the microbiome to support mental health.” Pic: Clare Keogh

We are what we eat — but does what we eat also impact our stress levels? New research from UCC would suggest so.

In recent years we have become aware of the tangible links between body and brain. We’ve learned new terms like gut microbiota — the two kilos of microorganisms that live in your digestive tract — and how they can significantly impact brain health and everyday mood.

A paper recently released by APC Microbiome Ireland at UCC with the eye-catching title ‘Feed your Microbes to Deal With Stress’ delves into how diet can support mental health. 

This study focused on a psychobiotic diet, which came to widespread attention with the 2017 publication of The Psychobiotic Revolution: Mood, Food, and the New Science of the Gut-Brain Connection. 

In this book, John F Cryan and Ted Dinan, UCC professors of neuroscience and psychiatry, respectively, along with journalist Scott C Anderson, made complex ideas understandable to those outside the scientific world. 

It was a fascinating premise: your brain health is connected to your microbiome and issues like stress, depression, and anxiety can be positively affected by a psychobiotic diet.

“We coined the term [psychobiotic diet] almost a decade ago,” says Cryan. “It’s a way of describing eating for the microbiome to support mental health.”

Two of the main components are fibre (“really important — it provides energy to the microbiome”) and fermented foods (“good at countering some of the changes that occur in our microbial diversity as we age”), along with coloured foods that are rich in polyphenols and a diverse diet.

The research was designed and led by registered dietitian and post-doctoral researcher Kirsten Berding with Cryan and Dinan. For the study, which took place over four weeks, 45 healthy adults were split into two groups, with 24 participants instructed to follow a psychobiotic diet while the other 21 formed the control group.

Though a relatively small number of people were involved — covid, points out Cryan, made it “a challenge to recruit and maintain people on the diet” — the results were impressive. Those who followed the psychobiotic diet had a 32% reduction in perceived stress. This reduction occurred despite no change in the participants’ everyday pressures. The paper also noted that “higher adherence to the diet resulted in stronger decreases in perceived stress”.

Pictured L-R: Professor John Cryan, Vice President for Research & Innovation UCC, Principal Investigator, APC Microbiome Ireland, and Professor Ted Dinan, Professor of Psychiatry, Principal Investigator in APC Microbiome Ireland. Pic: Clare Keogh.

As Cryan points out: “It’s important we realise that it’s not stress that kills us, it’s our reaction to it. It’s how the person subject to it perceives events as stressful.”

The psychobiotic diet recommended to participants included whole grains, prebiotic fruits and vegetables (sources of indigestible fibre), fermented foods, and legumes like dried peas, beans, and lentils. Consumption of fast food, soft drinks, and sweets was discouraged.

“We’re not eating for ourselves, we’re eating for the microbiome in our gut,” says Cryan. “We need to come up with solutions that we can democratise for populations, people who are not necessarily willing to go into health food shops. Solutions that can offer benefit to the community.”

These can also be solutions that are enjoyable, low in cost and taste delicious. A list of prebiotic fruits and vegetables includes inexpensive and readily available items like onions, garlic, leeks, and bananas. Low-cost legumes, in either dried or canned formats, are valuable sources of essential vitamins and minerals, fibre, and plant-based protein.

Cryan, who makes his own fermented milk kefir, is a strong advocate for eating fermented foods: “Get as much fermented food into your diet as possible, things like sauerkraut, kimchi, and kombucha.”

While Cryan acknowledges that more work is needed — “we are now doing a much larger scale study right now” — notes that diet-based solutions to perceived stress “will not work for everyone — everyone’s microbiome is different”.

That said, eating these foods will undoubtedly benefit your gut and may even help your stress levels.

Here’s what the subjects ate during their psychobiotic diet:

Six to eight daily servings: prebiotic fruits and vegetables — asparagus, onions, garlic, leeks, cabbage, Jerusalem artichokes, apples, bananas, etc.

Five to eight daily servings: whole grains.

Two to three daily servings: fermented foods, for example, sauerkraut, kimchi, kefir, kombucha. (One serving = 200ml or one cup.)

Three to four servings per week: legumes, eg, chickpeas, lentils, kidney beans.

Foods avoided: processed foods, foods containing artificial sweeteners or emulsifiers, fast food, soft drinks, and sweets.