Physical, mental and biochemical effects of probiotics in multiple sclerosis: A systematic review and meta-analysis.

BACKGROUND AND AIMS: This systematic review and meta-analysis aimed to evaluate the effects of probiotic supplementation on physical, mental, and biochemical outcomes in adults with multiple sclerosis (MS). METHODS: A comprehensive search of major databases (PubMed, Embase, Scopus, Cochrane Library, and Web of Science) following PRISMA guidelines for studies published up to December 2025. RESULTS: Six randomized placebo-controlled trials (RCTs) involving 282 participants met the inclusion criteria. Interventions varied in probiotic strains, doses, and duration. Quantitative synthesis showed that probiotic supplementation produced significant beneficial effects on motor outcomes, particularly fatigue and pain. No significant improvements were observed in disability status measured by the Expanded Disability Status Scale. Mental health outcomes, including depression and general psychological well-being, did not demonstrate statistically significant changes following probiotic use. In addition, biochemical analyses revealed a moderate overall benefit, driven primarily by reductions in systemic inflammatory markers, including high-sensitivity C-reactive protein. Effects on oxidative stress parameters were inconsistent, though some studies reported decreased malondialdehyde levels and improved antioxidant capacity. CONCLUSION: Overall, findings suggest that probiotics may offer moderate benefits for symptom management in MS, particularly for fatigue, pain, and inflammation, while evidence for effects on mental health remains limited. Further well-designed, multi-ethnic RCTs integrating microbiome and immunological assessments are needed to confirm these results and clarify underlying mechanisms. PROSPERO registration number: CRD42024511183.