From Gut to Mind: Impact of Probiotics on Depression, Anxiety, Mood, Gut Microbiota, Sleep and Stress-A Systematic Review of RCTs.

BACKGROUND: Probiotic supplementation may influence mental health through the gut-brain axis, with potential effects on depression, anxiety, sleep, cognition, stress hormones, and gut microbial composition. This systematic review aimed to evaluate the effects of probiotics on psychological, physiological, and gut microbiome-related outcomes across diverse populations. SUMMARY: A comprehensive search of PubMed, MEDLINE, PsycINFO, and ScienceDirect identified randomized controlled trials evaluating probiotic supplementation. Twenty RCTs were included, of which 15 were assessed as having a low risk of bias and five as having a high risk of bias. Commonly assessed outcomes included depression (n = 17), anxiety (n = 10), sleep quality (n = 9), stress (n = 6), cortisol (n = 7), cognitive function (n = 5), quality of life (n = 5), gut microbial composition (n = 11), and other neuroendocrine and inflammatory markers. Overall, probiotics were associated with improvements in depression, anxiety, sleep quality, mood, cognition, quality of life, and beneficial gut microbial populations, although findings for cortisol and stress-related outcomes were inconsistent. KEY MESSAGE: Probiotic supplementation may provide beneficial effects on psychological well-being and gut microbial composition. However, heterogeneity among interventions, populations, outcome measures, and study quality warrants further well-designed RCTs.