Abstract
Diet and age are important determinants of the human gut microbiota, which are essential for metabolic regulation, immune homeostasis and healthy ageing. In the current study, we examined the association of vegetarian and nonvegetarian dietary patterns with gut microbiome diversity, composition and function in an Eastern Indian population. Using 16S rRNA V3–V4 sequencing, we profiled gut microbial communities in 18 healthy subjects divided into three age groups (20–35, 40–60 and ≥ 70 years). Young adult nonvegetarians appear to have more microbial richness than vegetarians; however, vegetarians have higher microbial evenness, with a substantial age‐dependent change in both stability and variability. Pareto analysis revealed that vegetarians carried a lower abundance of harmful bacterial taxa but had a higher abundance of beneficial bacteria. Predicted functional profiling suggested that vegetarian gut microbiomes were predominantly enriched in biosynthesis and energy metabolism pathways associated with fibre fermentation and short‐chain fatty acid production. By contrast, nonvegetarian gut microbiomes were enriched for pathways related to the degradation of amino acids, lipids and xenobiotics. Interestingly, older vegetarians had a core gut microbiome with less functional dispersion but no changes in richness, indicating increased stability as they aged. Overall, gut microbial community structure did not differ significantly by diet or age (PERMANOVA), although profiles were broadly similar among the dietary patterns; some subtle differences regarding certain taxa were observed:
Bacteroides
,
Phocaeicola
,
Comamonas
,
Hungatella
and
Faecalimonas
were different in vegetarians, whereas
Segatella
,
Leyella
,
Dialister
,
Alloprevotella
and
Dorea
were abundant in nonvegetarians. These results suggest that long‐term dietary patterns of a particular type are associated with subtle shifts in specific microbial taxa, which may be relevant to metabolic homeostasis and healthy ageing without significantly altering community structure.