Food for thought
They’re the gut-health MVP, but should fermented foods be considered bona fide cortisol calmers?
THE EXPERT
Move your body. Practise mindfulness. Get a good night’s sleep. All sound advice in the battle to beat stress. But what you’re putting on your plate can also be a great antidote – and not just the first bite of pizza after a day you’d rather forget (although there’s a time and place for that, too).
I suspect you, WH reader, are familiar with the concept that food can influence your mood – and that it does so via the gut-brain axis. Multiple studies have shown that changes in gut microbiota are linked to stress-related physiology and behaviour. And given that strains of bacteria in the gut produce around 90% to 95% of the body’s serotonin, it’s no surprise that keeping your gut healthy can also help keep you happy.
Eating high-fibre foods, such as oats, whole grains and pulses, is a good place to start; doing so can increase the diversity of the microbiome and promote good gut health. But it’s also thought that having a psychobiotic diet – one high in fibre and fermented foods – may contribute to mental wellbeing by lowering stress levels. And while this research topic is still new, the evidence so far is compelling.
A recent randomised, controlled study* investigated the effects of a psychobiotic diet on stress, general health and microbial function in healthy adults who tend to eat low-fibre diets. The psychobiotic group were told to aim for six to eight servings of fruit and veg high in prebiotic fibre (such as apples and cabbage), five to eight servings of grains and two to three servings of fermented foods (such as kefir, sauerkraut and kombucha) every day. They were also instructed to eat three to four servings of legumes (chickpeas, kidney beans, lentils) per week.
Over four weeks, they saw a 32% reduction of perceived stress, compared with the control group, who only enjoyed half this perceived stress reduction. The psychobiotic diet also improved both sleep quality and duration – two key factors in lowering stress. While the psychob
