The effect of probiotics on depressive symptoms: A meta-analysis of randomized controlled trails

Abstract

Increasing evidence indicates bidirectional communication occurs between the gut and the brain via the microbiome-gut-brain axis. Accordingly, several studies point to a positive effect of probiotics on depressive symptomatology. Our study aimed to provide an updated meta-analysis on the subject. We conducted a systematic search for randomized clinical trials in multiple databases. Data analysis was performed using the Review Manager 5.4. We reviewed 26 studies, totaling 2,170 participants. The use of probiotics had a significant effect in reducing depressive symptoms (SMD: - 0.22; 95% CI: - 0.30 to - 0.13; p < 0.0001) compared to placebo. Subgroup analyses showed that probiotics influenced outcomes in participants with depression (SMD: - 0.67; 95% CI: - 0.93 to - 0.41; p < 0.00001) and with other clinical diagnoses (SMD: - 0.23; 95% CI: - 0.36 to - 0.09; p = 0.0008) but not healthy participants (SMD: - 0.11; 95% CI: - 0.23 to 0.02; p = 0.100). The use of probiotics can be a promising approach in improving the treatment of depression. It is important to conduct further studies to better assess the efficacy of probiotic as an adjuvant treatment to antidepressant medications, as well as their most effective dosages.