Variations in faecal bacterial enzyme activities and associations with bowel function and diet in elderly subjects

Daily and inter-individual variations of faecal bacterial β-glucuronidase and β-glucosidase activities and their associations with parameters of bowel function were studied in 10 residents of an old people's home during two 1-week periods 2 weeks apart. The effect of sampling method (a spot sample vs an aliquot of the homogenized sample from a total daily collection) on the activities of these enzymes and that of urease was also assessed. Intestinal transit time was determined using the radio-opaque Sitzmark^®; capsules, and questionnaires on bowel function and intakes of fluids and fibre-containing foods were completed. The mean (95% confidence interval) β-glucuronidase and β-glucosidase levels were 3·08 (2·75–3·41) and 11·53 (10·79–12·26) nmol min^?1 mg protein^?1. Daily variations in enzyme activities within individuals were not significant ( P = 0·277 and 0·990, respectively), whilst those between individuals were highly significant ( P = 0·000). Faecal frequency correlated negatively with β-glucuronidase and urease, but no other associations of the enzymic activities with parameters of bowel function and diet were observed. β-Glucuronidase and β-glucosidase were not affected by the sampling method, while significantly higher urease was obtained by spot sampling as compared with the aliquot representing the total daily collection. Large inter-individual variations in faecal enzyme activities should be taken into consideration when planning experiments and interpreting results on these faecal parameters.