Intestinal Microbiome in the Elderly
The intestinal microbiome seems to play a putative role in the fragility and vulnerabilities associated with the aging process.
Several studies have shown that the age-related change of the microbial composition of gastrointestinal tract is not a linear process: Marked changes appear later than originally expected; longevity appears to be associated with a markedly different microbi- ome (Biagi et al., 2010; Claesson et al., 2011). Many scientists agree that microbial diversity is reduced in elderly people. Bacteroides and firmicutes are the two main phyla in the young, and they remain prominent in older ages as well. However, probably some change, not yet completely known, occurs in the ratio of these phyla. In the elderly, there is a trend for a higher presence of pathogenic bacteria (pathobionts) than beneficial bacteria (symbionts), expressed by an increase of proteobacteria and a decrease of bifidobacteria populations. There is an age-related reduction in short-chain fatty acid production; that could be problematic, since butyrate is particularly important in maintaining the colonic epithelial integrity and reducing inflammation.