Review: Effects of probiotic supplementation on anxiety and depression

In this article, researchers from York University and McMaster University in Canada systematically evaluated current literature on the impact of probiotic supplementation on human anxiety and depression symptoms. Their review was published in the journal Nutrition Research.

• Gastrointestinal (GI) microbiota, which refers to microbial communities in the GI tract, play an important role in digestion, metabolism, and immunity.
• According to pre-clinical studies involving rodents, alterations in these bacterial communities can cause behavioral and neurochemical changes in the central nervous system.
• On the other hand, probiotic supplementation in rodents has caused marked improvements in behavior as well as central neurochemistry.
• However, while several studies have documented behavioral and mood-related supplementation effects, their significance in humans, especially in relation to anxiety and depression symptoms, has not yet been explored.
• For this review, the researchers searched multiple databases for randomized controlled trials (RCTs) published between January 1990 and January 2016. They found 10 RCTs — four in clinically diagnosed and six in non-clinical samples — that provided limited support for the use of probiotics in alleviating anxiety and depression symptoms in humans.
• Despite the methodological limitations of the trials and the complexity of gut-brain interactions, the results of most of the studies hinted at the psychological benefits of probiotic supplementation.

The researchers concluded that a better understanding of developmental, modulatory, and metagenomic influences on GI microbiota, especially in relation to mood and mental health, is needed and should be prioritized by future studies in this area.

Journal Reference:

Pirbaglou M, Katz J, Souza RJD, Stearns JC, Motamed M, Ritvo P. PROBIOTIC SUPPLEMENTATION CAN POSITIVELY AFFECT ANXIETY AND DEPRESSIVE SYMPTOMS: A SYSTEMATIC REVIEW OF RANDOMIZED CONTROLLED TRIALS. Nutrition Research. September 2016;36(9):889–898. DOI: 10.1016/j.nutres.2016.06.009