We have known for some years now that there is a comorbidity between psychological problems such as depression and anxiety and gastrointestinal disorders. That is to say people who present with these psychological problems often have a gut issue at the same time and vice versa. Recent research that has started to explain some of the processes underlying this relationship and the term given to this connection is the ‘gut-brain axis’. The community of bacteria in the gut is central to the gut-brain axis with the bacteria playing an essential role in nutrient absorption and production, inflammation and immunity amongst many others.

Much of the research into the gut-brain axis is of potential treatments: the researchers are looking to relieve a particular disorder and so the results can often only accurately be applied to groups who suffer from that disorder. However, a recently presented study looked at the effects of probiotic (beneficial bacteria) supplementation on healthy people.

Researchers from Ireland put 22 male participants through a battery of tests to assess their cognitive performance, perceived stress and stress hormone levels before and after a four-week course of a daily supplement of the bacteria Bifidobacteria longum. At the end of the study the participants reported feeling less anxious and stressed, had significantly improved cognition scores and were producing lower levels of stress hormones.