A study found probiotics may help improve mood characteristics associated with an increased risk of depression and anxiety. Published in Brain, Behaviour, and Immunity, the study provided a multistrain probiotic supplement to 20 healthy, depression-free young adults for four weeks, while giving a placebo to the other 20 participants. The probiotic supplement contained Bifidobacterium bifidum,Bifidobacterium lactis,Lactobacillus acidophilus,Lactobacillus brevis,Lactobacillus casei,Lactobacillus salivarius, and Lactococcus lactis. Before and after the supplementation period, all participants took two social cognitive tests and filled out a questionnaire aimed at determining symptoms of and risk factors for depression and anxiety. At the end of the four weeks, researchers discovered that:

• The probiotics group had a greater reduction in aggressive and ruminative thoughts, as compared to the placebo group. Ruminating—responding to a sad mood by dwelling on the causes and consequences of the sadness—has been associated with transforming a sad mood into a depressive episode.

Research on the relationship between probiotics and mood is still in its infancy, and more clinical trials are needed to confirm these findings, as well as to clarify which probiotic strains (and under which conditions) produce the best results. Nevertheless, the findings are consistent with some other animal and human studies which have dicovered probiotics may positively influence a wide range of mood states, including depression, anxiety, and stress.

Source: Brain, Behaviour, and Immunity