Associations between gut microbiota and osteoporosis or osteopenia in a cohort of Chinese Han youth.

Osteoporosis (OP) is a common metabolic bone disease characterized by low bone mass and microstructural deterioration of bone. Changes in the composition and structure of gut microbiota (GM) are related to changes of bone mass and bone microstructure. However, the relationship between GM and bone mineral density (BMD) is complex, and data are especially scarce for Chinese Han youth. Therefore, 62 Chinese Han youth participants were recruited. Furthermore, according to the T-score evaluation criteria of the World Health Organization (WHO), we divided the BMD levels of participants into three groups: osteoporosis\BDL, osteopenia\BDM, normal bone density\BDH, and the associations between GM community and BMD groups were conducted. According to alpha and beta diversity analysis, significant differences were found in the microbial richness and composition between groups. The dominant phyla of GM in a cohort of Chinese Han youth were Bacteroidota (50.6%) and Firmicutes (41.6%). Anaerobic microorganisms, such as g_Faecalibacterium and g_Megamonas, account for the largest proportion in the gut, which were mainly Firmicutes phylum. The dominant genera and species in the three BMD groups were g_Prevotella, g_Bacteroides, g_Faecalibacterium, g_Megamonas, s_Prevotella copri, s_unclassified_g_Faecalibacterium, s_unclassified_g_Prevotella, s_unclassified_g_Bacteroides and s_Bacteroides plebeius. g_Faecalibacterium, g_Bacteroides and g_Ruminococcus differed between the BDH and BDL groups as well as between the BDH and BDM groups. LEfSe showed three genus communities and eight species communities were enriched in the three BMD groups, respectively. The associations between microbial relative abundance and T-score was not statistically significant by Spearman and regression analysis. In conclusion, the alpha diversity indexes in the BDH group were higher than in the BDL group, and several taxa were identified that may be the targets for diagnosis and therapy of OP.