Short chain fatty acids, especially butyric acid, produced by many microbiota are considered as a sign of good bowl health and as nutrients and regulators of inflammatory pathways and gene expression in the gut epithelium. The influence of the composition of bacterial population and diet on intra individual differences in metabolites, particularly SCFAs, and colonic health is poorly understood. To investigate whether there is a specific difference in butyrate production trough the individual composition of microbiota affected by diet, age, activity and other life style factors, SCFAs were measured using HPLC-IR. Furthermore, abundance of the Butyryl-CoA CoA-transferase gene was analysed with gene specific touchdown real time -PCR applying degenerate primers. Samples were gained from geriatric subjects and from subjects with a vegetarian diet or a western mixed diet.