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Effect of probiotic and prebiotic vs placebo on psychological outcomes in patients with major depressive disorder: A randomized clinical trial
While the imbalancing of microbiota in the gut has been associated with the pathophysiology of depression, Kazemi et al. (2019) identified probiotics as potential positive modulators of the gut microbiome, and prebiotics as possible growth stimulators for some beneficial bacterial species in the gut. This double-blind clinical trial compared the effects of probiotics with prebiotics on patients with major depressive disorder (MDD), using the Beck Depression Inventory (BDI) score as a primary outcome, and the kynurenine/tryptophan ratio and tryptophan/branch chain amino acids (BCAAs) ratio as secondary outcomes. The participants (n=110) were randomly assigned to receive the probiotic (Lactobacillus helveticus and Bifidobacterium longum), prebiotic (galactooligosaccharide) or placebo for 8 weeks. Eighty one subjects completed the trial, with 28 in the probiotic group, 27 in the prebiotic group, and 26 in the placebo group. While serum kynurenine/tryptophan ratio and tryptophan/BCAAs ratio were not significantly different among the 3 groups, the kynurenine/tryptophan ratio in the probiotic group were significantly lower compared to the placebo group after adjustments were made for serum isoleucine. Additionally, the tryptophan/isoleucine ratio was significantly greater in the probiotic group than the placebo group (p = 0.023). Regarding depressive symptoms, BDI scores dropped significantly more after 8 weeks of probiotic supplementation (17.39-9.1), compared with those on prebiotics and on placebo. Although prebiotics’ effects were not significant, BDI scores improved after 8 weeks of administering probiotic supplements to patients with MDD. [NPID: probiotics, gut-brain axis, gut microbiota, gut bacteria, microbiota, gut microbiome, depression, prebiotics, major depressive disorder, MDD, tryptophan, brain chain amino acids, BCAAs, Lactobacillus helveticus, Bifidobacterium longum, kynurenine]
Year: 2019
