The use of probiotics in depression
Probiotics are thought to play a role in the extensive bidirectional communication between gut microbiota and the brain. A growing body of preclinical data suggests that probiotics may be effective in alleviating low mood and improving depressive symptoms. Preliminary evidence derived from studies in rodent models supports the view that single-strain or multi-strain preparations of Bifidobacterium and Lactobacillus are able to improve behaviors related to depression. The extent of antidepressant effects in humans with a clinical diagnosis of depression is less clear. While some support for the efficacy of probiotic supplementation has been found, the pooled effects in meta-analyses have generally been small. The positive effects reported for probiotics in major depression should be regarded as preliminary. Large, randomized trials assessing the efficacy of specific probiotic strain combinations over various time spans in individuals with clinically significant presentations of depression are needed to evaluate the therapeutic potential of probiotics. In light of accumulating evidence showing that probiotics may have beneficial effects in reducing depressive symptoms and may be useful as an adjunct intervention in major depressive disorder, the efficacy of probiotic foods in the prevention of depression should be investigated.