FECAL BACTERIAL ENZYME-ACTIVITIES IN INFANTS INCREASE WITH AGE AND ADOPTION OF ADULT-TYPE DIET

Background: The present study was conducted to determine the effects o f age and diet (breast milk, milk formula, weaning diet) on the activi ties of some bacterial enzymes in fecal samples collected from 3- to 2 4-month-old infants. These bacterial enzymes may generate toxic, mutag enic, or carcinogenic metabolites from plant glycosides (beta-glucuron idase, beta-glucosidase) or from urea (urease). Methods: The subjects were 68 healthy children ages 3 (n = 20), 6 (n = 20), 12 (n = 17), and 24 (n = 11) months. None of the children had been given any antibioti cs during 4 weeks before collection of the fecal samples. Health statu s, bowel habits, and food consumption of the children were determined by interview of one of the parents using a structured questionnaire. A spot fecal sample from each child was collected. Results: The activit ies of beta-glucuronidase and beta-glucosidase increased from 0.52 and 1.17 nmol/min x mg protein (at 3 months) to 1.41 and 2.38 nmol/min x mg protein (at 2 years), respectively. However, at 2 years of age, the children had not yet reached the levels reported in earlier studies o n adult populations. Urease activity increased from 4.18 nmol/min x mg protein (at 3 months) to 19.0 nmol/min x mg protein (at 2 years), rea ching by 12 months of age the level observed in adults. Breast feeding as such had no consistent effect on fecal bacterial enzyme activities . beta-Glucuronidase and beta-glucosidase were higher in those 6- and 12-month-old children who consumed more meat, fish, sausages, or eggs. Conclusions: It can be concluded that the fecal enzyme activities in the gastrointestinal tract increase and that their profile changes wit h age and adoption of adult-type diet, It remains open, however, wheth er these changes are caused by the normal physiological aging process or by stepwise introduction of new foods to the diet. (C) 1997 Lippinc ott-Raven Publishers.