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

Daily and inter-individual variations of faecal bacterial beta-glucuronidase and beta-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) beta-glucuronidase and beta-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 beta-glucuronidase and urease, but no other associations of the enzyme activities with parameters of bowel function and diet were observed. beta-Glucuronidase and beta-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.