Abstract
The objective of this study was to determine the effect of weaning on the ability of formula-fed infants to ferment complex carbohydrates. A cross-sectional study of 46 infants was performed. Fresh faeces were collected from normal exclusively formula-fed infants at pre- ( n =15), early ( n =15) and late weaning ( n =16). Faecal bacteria were incubated with simple and complex carbohydrates (glucose, lactose, raftilose and soyabean polysaccharide) in vitro. In addition, a control culture with no added carbohydrate was also incubated. Short-chain fatty acids (SCFA) and lactate were measured in culture supernatant after anaerobic incubation for 24 hours. There were no significant differences between any stages of weaning for SCFA production for any substrate. However, there was a consistent trend for the percentage of butyric acid production to increase with age. The greater similarity of the colonic flora of the formula-fed infants to that of the adult results in less impact of weaning on the development of fermentation capacity for complex carbohydrates than that previously reported for the simpler flora of the breast-fed infant.