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

ABSTRACT

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 (n = 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 (n = 214 participants; WMD = 3.08 ng/mL, 95% CI: 1.83, 4.34; P = 0.001; I²= 7.5%; P-heterogeneity 0.34), or depression (n = 268 participants; WMD = 0.77 ng/mL, 95% CI: 0.07, 1.47; P = 0.032; I²= 88.4%; P-heterogeneity < 0.001). Furthermore, a significant increase in BDNF levels was found in studies that administered the mixture of Lactobacillus and Bifidobacterium genera, 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 Lactobacillus and Bifidobacterium 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.

KEYWORDS:

• Probiotics
• BDNF
• meta-analysis
• systematic review
• Bifidobacterium
• depression
• Lactobacillus
• microbium
• gut microbiota

Acknowledgements

FD, SS, and SA: designed the review; FD and SA: conducted major database search according to search strategy; FD and SS did data extraction; SS: performed analysis; FD, SA, SS, CC and FS: wrote the manuscript’s draft; and all authors: evaluated the final version of the manuscript precisely and approved it.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author (SS), upon reasonable request.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Shahid Sadoughi University of Medical Sciences, Yazd, Iran [grant number 11219]. The funding source played no role in study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the article for publication.

Notes on contributors

Fereshteh Dehghani

Fereshteh Dehghani she is PhD candidate of nutrition science at Texas Tech University.

Shima Abdollahi

Shima Abdollahi is assistant professor of nutrition sciences in North Khorasan University of Medical Sciences.

Farzad Shidfar

Farzad Shidfar is full professor of nutrition sciences in Iran University of Medical Sciences.

Cain C. T. Clark

Cain C. T. Clark is assistant professor (Research) in Centre for Intelligent Healthcare.

Sepideh Soltani

Sepideh Soltani is assistant professor of nutrition sciences in Shahid Sadoughi University of Medical Sciences. All Authors published many systematic reviews, meta-analyses in the association between nutrition and risk of chronic disease, health status, and circulating level of health biomarker.