مقالات پذیرفته شده در نهمین کنگره بین المللی زیست پزشکی
Effect of Microbiome on the Mood: A Meta-Analysis of Lactobacillus rhamnosus in Depression
Effect of Microbiome on the Mood: A Meta-Analysis of Lactobacillus rhamnosus in Depression
Zeinab Mohsenipour,1,*
1. Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Introduction: The gut-brain axis is increasingly becoming an extremely promising area for finding new therapies for mental illness, including depression. The communication between our brains and our guts is not just about digestion but also relates to our emotions and thoughts. Lactobacillus rhamnosus is one of the most studied probiotics for effects on the brain and is particularly interesting in regulating brain chemistry and inflammation. This meta-analysis looks into whether taking supplements of L. rhamnosus supplements could help adults relieve depressive symptoms.
Methods: We undertook a search of major databases like PubMed, Scopus, Embase, and Cochrane Central up to 2025 to find randomized clinical trials in adults with depression or depressive symptoms. We prioritized studies that used established scales for depression, such as the Beck Depression Inventory (BDI), Hamilton Depression Rating Scale (HDRS or HAM-D), or Patient Health Questionnaire-9 (PHQ-9), and contrasted L. rhamnosus supplementation with placebo. The data were pooled according to the random-effects model to get a good estimate of the overall effect. We also looked at the quality of the studies and checked for any inconsistency or bias.
Results: 41 out of 80 trials with a total of 402 participants met our inclusion criteria. Overall, patients who received L. rhamnosus experienced a significant decrease in their symptoms of depression compared to patients who received placebo. The effect was small but apparently real, with an SMD of –0.27. When we looked in more detail, the effects were more evident in those who took the supplement for eight weeks or more and in those with mild depression at baseline. The trials were generally similar to each other (low heterogeneity), and there was no evidence that selective reporting of only good results had taken place.
This meta-analysis suggests that L. rhamnosus might decrease depressive symptoms, but it is not a magic pill. Some of the ways it might possibly do that are soothing the body's stress system (HPA axis), boosting calming neurotransmitters like GABA, decreasing inflammation, and keeping the lining of the gut healthy. However, there are limitations—different studies used different strains and doses and measured different outcomes, so some can't be compared.
Conclusion: We hope to see more studies that control for the means of L. rhamnosus, assess longer-lasting outcomes, and examine more closely the mechanisms of action of this probiotic at the level of the brain in the future. In the meantime, this meta-analysis adds further support to the notion that purposefully using targeted probiotics like L. rhamnosus may be a beneficial complement to a broader treatment strategy for depression alongside more conventional therapeutic approaches.