The link between gut bacteria and stress

The idea that bacteria from your gut could influence your brain and mood may sound odd, but there is growing evidence to support it. Recently scientists from Oxford University made an important advance in this field of research with a study of prebiotics and its effect on stress levels and emotional processing.

There are two ways you can manipulate the microbes in the gut, you can consume probiotics (live cultures of bacteria) or you can consume prebiotics (types of sugar molecules). Previous studies have revealed that probiotics can in fact alter the way the human brain functions; up until now however, prebiotic effects had only been noted in animals.

This study was particularly concerned with the effect prebiotics have on emotion and stress-related disorders. In the past, research has found that probiotics can lower anxiety, so this study wanted to see if prebiotics would do the same.

Healthy volunteers took either a placebo or one of two different prebiotics, B-GOS or FOS, for a period of three weeks. At the end of the trial period, participants completed a series of tests to compare emotional processing.

The study found that those who had taken the prebiotic B-GOS paid more attention to positive words and less attention to negative words when compared to those who took the placebo. Participants who had taken B-GOS also had lower levels of cortisol (the stress hormone) in their saliva when compared to the beginning of the trial.

Interestingly these findings were not found in those who had taken the FOS prebiotic, highlighting the fact that different prebiotics provide different results. In terms of attention being paid to certain words in those taking B-GOS, the results found were similar to those seen when people take anti-anxiety or anti-depressant medication.

The senior author of the study, Dr Philip Burnet has noted that prebiotics and probiotics are unlikely to be administered as an alternative to current pharmacological and psychological treatments, but instead may be used in conjunction with them.

Research into the link between microbiome and the brain is likely to heat up in the coming years as we learn more about the way the body handles stress and how manipulations may be able to help those in need.