Probiotics supplementation and brain-derived neurotrophic factor (BDNF): a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND AND AIMS

An emerging body of evidence has demonstrated the beneficial effects of probiotics on various mental health conditions. In this systematic review and meta-analysis, we sought to examine the effects of probiotics supplementation on brain-derived neurotrophic factor (BDNF) in adults.

METHODS

PubMed, Scopus, ISI Web of Science, and the Cochrane Library were searched, from database inception to April 2021, for eligible randomized controlled trials (RCTs). We pooled mean differences and standard deviations from RCTs using random-effect models.

RESULTS

Overall, meta-analysis of 11 trials ( = 648 participants) showed no significant changes in serum level of BDNF following probiotics. However, subgroup analysis revealed that probiotics increased BDNF levels in individuals suffering from neurological disorders ( = 214 participants; WMD = 3.08 ng/mL, 95% CI: 1.83, 4.34;  = 0.001; = 7.5%; P-heterogeneity 0.34), or depression ( = 268 participants; WMD = 0.77 ng/mL, 95% CI: 0.07, 1.47;  = 0.032; = 88.4%; P-heterogeneity < 0.001). Furthermore, a significant increase in BDNF levels was found in studies that administered the mixture of and , and were conducted in Asia .

CONCLUSION

Our main findings suggest that probiotics may be effective in elevating BDNF levels in patients with depression and neurological disorders, and a mixed of and appear to show greater efficacy than the single genus supplement. The low quality of evidence reduces clinical advocacy, and indicates that more large-scale, high-quality, RCTs are needed to facilitate reliable conclusions.