The ‘gut-brain axis’ has garnered more and more attention in recent years, and with good reason. When we feel stressed, our digestive systems can go haywire – we’ve all felt the need to dash to the loo when we’re really nervous. And increasingly, we’re finding out that what we eat can impact what goes on in our heads too.
With up to 95% of our serotonin (the happy hormone) made in the gut, it makes sense that we can improve mood and wellbeing via our stomachs. And a new study has concluded that the kinds of foods that help to keep our guts healthy and happy do the same for our stress levels.
Members of APC Microbiome Ireland found that eating more fermented foods and fibre (two stalwarts of good gut nutrition) every day for just four weeks can significantly reduce perceived stress levels.
Scientists recruited 45 healthy people aged 18-59 who tend to eat relatively low-fibre diets. They were split into two groups: one was put on a ‘psychobiotic’ diet packed with prebiotic and fermented foods linked to better mental health. They were told to aim to eat six-to-eight servings a day of fruits and vegetables high in prebiotic fibres (like onions, leeks, cabbage, apples, bananas and oats), five-to-eight servings of grains and three-to-four of legumes a week.
They were also asked to eat two or three servings of fermented foods like sauerkraut and kombucha a day. The other group were given general dietary advice based on current healthy eating guidelines.
Within four weeks, those who followed the psychobiotic diet reported feeling less stressed compared to the control group, and scientists noticed a direct correlation between how strictly participants followed the diet and their perceived stress levels – with those who had more psychobiotic foods reporting the greatest reduction of stress.
They also reported greater improvements in sleep quality. Interestingly, one of the study’s authors, John Cryan, from University College Cork, writes in The Conversation that people only experienced mild changes in the composition and function of gut bacteria – although they did find “significant changes in the level of certain key chemicals” produced by the gut bugs present, and those chemicals have been linked to mental health. That, perhaps, explains why people felt less stressed after eating a diet tailored to those microbes.
As Cryan points out, a lot more research is still needed on the subject, but all of this just goes to show what we already know: the link between our guts and brains is strong. And while we can’t guarantee that eating a load of kimchi or more plants is necessarily going to undo the stress of a looming recession, that work presentation or the prospect of spending Christmas with your parents, you may just find that actively trying to eat more fibre (if possible) might reduce that everyday low-grade stress slightly.
4 fermented foods to eat more of every day
Fermented foods are so good for us, but not everyone loves super-tangy flavours. Regardless of your palate, there are ways to get more fermented goodness onto our plates.
Live yoghurt
Yoghurt tends to be made from milk that’s been fermented using lactic acid bacteria, and it’s packed with all sorts of nutrients like vitamin B12, calcium and potassium. If you don’t eat dairy, look for cultured coconut yoghurt, which will have probiotic lactobacillus bacteria. The Coconut Collab’s Gut Health Plain Yog has calcium and vitamins D, B6 and B12, as well as live cultures.
Kimchi
If you’re into super tangy tastes, then kimchi is one of the best pickles out there. Made from Chinese cabbage and usually a bunch of other veg, it makes the perfect accompaniment to beans on toast, curry and just about anything else. We love Kim Kong Kimchi.
Miso
Who doesn’t love a miso soup? That deep umami taste is super satisfying and moreish – and because miso is made from fermented soybeans, it’s a gut health hero. Loads of studies have confirmed its health benefits, including one involving nearly 22,000 Japanese women. It found eating miso soup was linked to a lower risk of breast cancer, while a bigger (40,000 people) study found miso soup was linked to a lower risk of stroke.
Tempeh
A great alternative for anyone looking to diversify their plant protein sources, tempeh is again made from fermented soybeans. It’s versatile (it’s great baked), it’s rich in probiotic bacteria and has been linked with reducing bad cholesterol.