FIGURE 1: Effects of age and aspects of the ageing process on the small bowel microbiome. Our findings indicate that the duodenal microbiome changes progressively and significantly in older subjects. This includes decreased microbial diversity, increased prevalence of phylum Proteobacteria and anaerobic microbes, increased coliform levels, and decreased prevalence of phylum Bacteroidetes. Changes in specific genera correlated with chronologic age alone (Bacteroides, Lactobacillus, Escherichia), number of medications (Klebsiella), or number of underlying conditions/concomitant diseases (Clostridium).