Abstract
BackgroundGut microbiota is critical in maintaining human health, of which diversity and abundance are subject to significantly reduce in seniors. Gut microbiota is reported to be stable across the long adulthood in general, but lack of careful examination, especially for the midlife people.ResultsTo characterize the gut microbiota in midlife, we investigated the faecal microbiota between two groups of healthy people, young, 20–39 years old, n = 15; and midlife, 40–60 years old, n = 15. Metabolic responses of the microbiota were studied through in vitro batch fermentation model. Although no difference was observed in the diversity indices between the two age groups, a wide range taxonomic changes were found in the faecal microbiota. Furthermore, substantial Bifidobacterium reduction was also found in both faecal and fermented samples. The faecal SCFAs are similar in both groups, as well as starch fermentation broth. However, after inulin fermentation, the acetate concentration and inulin degradation rate decreased while the gas production increased in midlife group, suggesting a deficiency of saccharolytic potential in midlife, especially for non-digestible carbohydrate.ConclusionsOur data demonstrate that gut microbiota begins to change as early as in midlife. The reduction in Bifidobacterium dominates the change of the microbiota composition in midlife resulting in attenuated saccharolytic capacity of inulin, possibly leading to insufficient acetate production which might be associated with healthy problems in this transition period from young to elderly.
Highlights
Gut microbiota is critical in maintaining human health, of which diversity and abundance are subject to significantly reduce in seniors
Combined with the analysis of microbiota composition, we found the age-related metabolic alterations were associated with the reduction of Bifidobacterium in midlife
Difference in the structure of the microbiota community Based on the results of the16S rRNA gene sequencing, the alpha-diversity indices, such as Shannon, Simpson and Chao1 index are similar between midlife and young in both faecal and fermented samples (Fig. 1a)
Summary
Gut microbiota is critical in maintaining human health, of which diversity and abundance are subject to significantly reduce in seniors. The gut microbiota of elderly lacks diversity and is less stable combined with. An integrative study of aging mice demonstrated that the relative abundance of Akkermansia spp., Bifidobacterium spp. and Lactobacillus spp. decreases at middle age compared to young subjects [12]. Boehme and colleagues revealed a strong basal and stress-induced neuro inflammatory profile in middle-aged mice, which is associated with the changes in both microbiota compositions and their metabolites [6]. Transfer of gut microbiota from young to middle-aged subjects extended the lifespan of the short-lived killifish [13]. A recent cohort study of middle age (50–59 years old) to elderly individuals (> 60 years old) revealed that the presence of Bacteroidetes is positively associated with CD8+ and negatively with CD4+/CD8+ ratio, indicating tendency to immune diseases such as chronic infection, cancer or HIV [14]
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