Effect of synbiotic supplementation on immune parameters and gut microbiota in healthy adults: a double-blind randomized controlled trial

• Published in: Gut microbes 2023-12, Vol.15 (2), p.2247025-2247025
• Main Authors: Li, Xiaoqin, Hu, Shan, Yin, Jiawei, Peng, Xiaobo, King, Lei, Li, Linyan, Xu, Zihui, Zhou, Li, Peng, Zhao, Ze, Xiaolei, Zhang, Xuguang, Hou, Qiangchuan, Shan, Zhilei, Liu, Liegang
• Format: Article
• Language: English
• Subjects: enterotypes; gut microbiota; immunomodulation; inflammation; Research Paper; secretory IgA; Synbiotics
• ISSN: 1949-0976; 1949-0984
• DOI: 10.1080/19490976.2023.2247025

Synbiotics are increasingly used by the general population to boost immunity. However, there is limited evidence concerning the immunomodulatory effects of synbiotics in healthy individuals. Therefore, we conducted a double-blind, randomized, placebo-controlled study in 106 healthy adults. Participants were randomly assigned to receive either synbiotics (containing Bifidobacterium lactis HN019 1.5 × 10 8 CFU/d, Lactobacillus rhamnosus HN001 7.5 × 10 7 CFU/d, and fructooligosaccharide 500 mg/d) or placebo for 8 weeks. Immune parameters and gut microbiota composition were measured at baseline, mid, and end of the study. Compared to the placebo group, participants receiving synbiotic supplementation exhibited greater reductions in plasma C-reactive protein (P = 0.088) and interferon-gamma (P = 0.008), along with larger increases in plasma interleukin (IL)-10 (P = 0.008) and stool secretory IgA (sIgA) (P = 0.014). Additionally, synbiotic supplementation led to an enrichment of beneficial bacteria (Clostridium_sensu_stricto_1, Lactobacillus, Bifidobacterium, and Collinsella) and several functional pathways related to amino acids and short-chain fatty acids biosynthesis, whereas reduced potential pro-inflammatory Parabacteroides compared to baseline. Importantly, alternations in anti-inflammatory markers (IL-10 and sIgA) were significantly correlated with microbial variations triggered by synbiotic supplementation. Stratification of participants into two enterotypes based on pre-treatment Prevotella-to-Bacteroides (P/B) ratio revealed a more favorable effect of synbiotic supplements in individuals with a higher P/B ratio. In conclusion, this study suggested the beneficial effects of synbiotic supplementation on immune parameters, which were correlated with synbiotics-induced microbial changes and modified by microbial enterotypes. These findings provided direct evidence supporting the personalized supplementation of synbiotics for immunomodulation.