Exploratory studies of oral and fecal microbiome in healthy human aging

Abstract

Growing evidence has linked an altered host fecal microbiome composition with health status, common chronic diseases, and institutionalization in vulnerable older adults. However, fewer studies have described microbiome changes in healthy older adults without major confounding diseases or conditions, and the impact of aging on the microbiome across different body sites remains unknown. Using 16S ribosomal RNA gene sequencing, we reconstructed the composition of oral and fecal microbiomes in young (23–32; mean = 25 years old) and older (69–94; mean = 77 years old) healthy community-dwelling research subjects. In both body sites, we identified changes in minor bacterial operational taxonomic units (OTUs) between young and older subjects. However, the composition of the predominant bacterial species of the healthy older group in both microbiomes was not significantly different from that of the young cohort, which suggests that dominant bacterial species are relatively stable with healthy aging. In addition, the relative abundance of potentially pathogenic genera, such as Rothia and Mycoplasma, was enriched in the oral microbiome of the healthy older group relative to the young cohort. We also identified several OTUs with a prevalence above 40% and some were more common in young and others in healthy older adults. Differences with aging varied for oral and fecal samples, which suggests that members of the microbiome may be differentially affected by aging in a tissue-specific fashion. This is the first study to investigate both oral and fecal microbiomes in the context of human aging, and provides new insights into interactions between aging and the microbiome within two different clinically relevant sites.

Analysis of the gut microbiome in sled dogs reveals glucosamine- and activity-related effects on gut microbial composition

“…Sato et al ( 78 ) observe that centenarians actually have increased alpha-diversity compared to a young control population as calculated by Shannon index. Studies taking into account health status across a broad age range suggest that there is little difference in microbiome complexity between healthy young and old groups ( 79 ), or observe stability or increases in Shannon diversity in very old participants ( 80 , 81 ). Health status and environmental factors are likely better predictors of microbiome composition than age ( 82 , 83 ), or at least must be taken into account when considering the complex interactions between aging and gut microbiota ( 84 , 85 ).…”

Nurturing longevity through natural compounds: Where do we stand, and where do we go?

“…The remodeling of the gut microbiome with aging is determined by individual factors, such as diet, drug therapy, and restricted social contact. Clarifying the composition of a healthy microbiome and its age‐ and disease‐related variations is subjected to an elevated interest due to solid scientific evidence for the interconnection between microbiota composition and longevity (Figure 4; Afzaal et al., 2022; K. Hou et al., 2022; Sepp et al., 2022; L. Wu et al., 2022; X. Zhou et al., 2022). The gut microbiome of centenarians is characterized with decreased abundance of health‐related symbionts found in young people (such as Faecalibacterium spp.)…”

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