Summary: Adding more fermented foods and fiber to your daily diet for four weeks has a significant impact when it comes to reducing stress.
Font: The conversation
When it comes to dealing with stress, we’re often told that the best thing we can do is exercise, make time for our favorite activities, or try meditation or mindfulness.
But the types of food we eat can also be an effective way to deal with stress, according to research published by me and other members of APC Ireland Microbiome. Our latest study has shown that eating more fermented foods and fiber daily for just four weeks had a significant effect on reducing perceived stress levels.
During the last decadea growing body of research has shown that diet can have a great impact on our mental health. In fact, a healthy diet can even reduce the risk of many common mental illnesses.
The mechanisms underlying the effect of diet on mental health are not yet fully understood. But one explanation for this link could be the relationship between our brains and our microbiome (the trillions of bacteria that live in our gut).
Known as the gut-brain axis, this allows the brain and gut to be in constant communication with each other, allowing essential bodily functions like digestion and appetite to occur. It also means that the emotional and cognitive centers of our brain are closely connected to our gut.
While previous research has shown that stress and behavior are also linked to our microbiomeUntil now, it was unclear whether changing our diet (and thus our microbiome) might have a different effect on stress levels.
This is what our study set out to do. To test this, we recruited 45 healthy people on relatively low-fiber diets, ages 18-59. More than half were women. The participants were divided into two groups and randomly assigned a diet to follow during the four weeks of the study.
About half were put on a diet designed by nutritionist Dr. Kirsten Berding, which would increase the amount of prebiotic and fermented foods they ate. This is known as a “psychobiotic” diet, as it included foods that have been linked to better mental health.
This group received an individual educational session with a dietician both at the beginning and in the middle of the study. They were told to aim for 6 to 8 daily servings of fruits and vegetables rich in prebiotic fibers (such as onions, leeks, cabbage, apples, bananas, and oatmeal), 5 to 8 daily servings of grains, and 3 to 4 servings of legumes a week.
They were also told to include 2 to 3 servings of fermented foods a day (such as sauerkraut, kefir, and kombucha). Participants on the control diet only received general dietary advice, based on the healthy eating food pyramid.
Less stress
Interestingly, those on the psychobiotic diet reported feeling less stressed compared to those on the control diet.
There was also a direct correlation between how strictly the participants followed the diet and their perceived stress levels, with those who ate the most psychobiotic foods over the four-week period reporting the greatest reduction in perceived stress levels.
Interestingly, sleep quality improved in both groups, although those on the psychobiotic diet reported greater improvements in sleep. Other studies have also shown that gut microbes are involved in sleep processeswhich may explain this link.
The psychobiotic diet caused only subtle changes in the composition and function of microbes in the gut. However, we did see significant changes in the level of certain key chemicals produced by these gut microbes. Some of these chemicals have been linked to mental healthwhich could explain why the dieters reported feeling less stressed.
Our results suggest that specific diets can be used to reduce perceived stress levels. This type of diet can also help protect mental health in the long run, as it targets microbes in the gut.
Although these results are encouraging, our study is not without limitations. First, the sample size is small due to the pandemic restricting recruitment. Second, the short duration of the study might have limited the changes we observed, and it’s not clear how long these would last. As such, long-term studies will be needed.
Third, although the participants recorded their daily diet, this form of measurement can be susceptible to error and bias, especially when estimating food intake. And while we did our best to make sure participants didn’t know which group they’d been assigned to, they may have been able to guess based on the nutrition advice they were given. This may have affected the answers they gave at the end of the study.
Finally, our study only looked at people who were already healthy. This means that we don’t understand what effect this diet might have on someone who is not so healthy.
Still, our study offers exciting evidence that an effective way to reduce stress may be through diet. It will be interesting to know if these results can also be replicated in people suffering from stress-related disorders, such as anxiety and depression. It also adds more evidence to this investigation Campshowing evidence of an association between diet, our microbiome and our mental health.
So the next time you’re feeling particularly stressed, you might want to think more carefully about what you plan to eat for lunch or dinner. Including more fiber and fermented foods for a few weeks can help you feel a little less stressed.
Money: John Cryan receives funding from Science Foundation Ireland (SFI), the Irish Research Council and the Health Research Board. He also receives funding from the Saks-Kavanaugh Foundation. The author receives research funding, has been a consultant, and has been on the Speakers Bureau for pharmaceutical and food companies in the field of microbiome, food, and neuroscience.
About this research news on stress and diet
Author: John Cryan
Font: The conversation
Contact: John Cryan – The Conversation
Image: The image is in the public domain.
