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

Xiaoqin Li, Shan Hu, Jiawei Yin, Xiaobo Peng, Lei King, Linyan Li, Zihui Xu, Li Zhou, Zhao Peng, Xiaolei Ze, Xuguang Zhang, Qiangchuan Hou, Zhilei Shan, Liegang Liu

Journal: Gut microbes 2023;15(2):2247025

PMID: 37614109

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The gut microbiota is involved in regulating immunity and synbiotics, that is combinations of pro- and prebiotics, may therefore modulate immunity via the gut microbiota. The aim of this randomised, double-blind, placebo-controlled trial was to evaluate the immune-modulatory effects of a synbiotic supplement (containing Bifidobacterium lactis HN019, Lactobacillus rhamnosus HN001 and fructo-oligosaccharide) in healthy adults. Outcome measures included C-reactive protein (CRP, an inflammatory marker), various pro- and anti-inflammatory cytokines, stool and salivary secretory IgA (sIgA), leukocytes, microbial stool analysis and occurrence, duration, and severity of upper respiratory tract infections (URTI). Compared to the control group, a significant reduction in the inflammatory markers CRP and interferon-gamma and an increase in the anti-inflammatory interleukin-10 and stool sIgA were observed in the supplementation group. There were no differences in types of leukocytes or URTIs between groups. Significant favourable changes in microbiome analysis were observed in the supplemented group which correlated with the observed improvements in inflammatory markers. These changes were dependent on the baseline composition of the microbiome. No adverse events were reported. The authors conclude that the data show that synbiotics are of benefit to healthy adults and support the concept of personalised supplementation.

Abstract

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 HN019 1.5 × 10 CFU/d, HN001 7.5 × 10 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 ( = 0.088) and interferon-gamma ( = 0.008), along with larger increases in plasma interleukin (IL)-10 ( = 0.008) and stool secretory IgA (sIgA) ( = 0.014). Additionally, synbiotic supplementation led to an enrichment of beneficial bacteria (, , , and ) and several functional pathways related to amino acids and short-chain fatty acids biosynthesis, whereas reduced potential pro-inflammatory 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 -to- (/) ratio revealed a more favorable effect of synbiotic supplements in individuals with a higher / 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.

Address: Department of Nutrition and Food Hygiene, Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.; Ministry of Education Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.; Academy of Nutrition and Health, Hubei Province Key Laboratory of Occupational, Hazard Identification and Control, School of Public Health, Wuhan University of Science and Technology, Wuhan, China.; Microbiome Research and Application Center, BYHEALTH Institute of Nutrition & Health, Guangzhou, China.; Hubei Provincial Engineering and Technology Research Center for Food Ingredients, Hubei University of Arts and Science, Xiangyang, Hubei province, China.

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