COLONIC FERMENTATION CAPACITY IN-VITRO - DEVELOPMENT DURING WEANING IN BREAST-FED INFANTS IS SLOWER FOR COMPLEX CARBOHYDRATES THAN FOR SUGARS

Fresh feces from 27 healthy infants-12 breastfed (complete, exclusive breast-feeding), 7 in early weaning (partial, high breast-feeding), an d 8 in late weaning (partial, low breast-feeding)-were cultured with s imple and complex carbohydrates in vitro to test the hypothesis that c olonic fermentation capacity for carbohydrates increases during weanin g. Infants in all three groups were able to ferment sugars, with no si gnificant differences in median total short-chain fatty acid (SCFA) co ncentrations (mmol/L): preweaning, 56.4 (range: 0-77.6); early weaning 68.5 (range: 57.9-98.8); late weaning, 61.3 (range: 28.6-120.4) for g lucose. Preweaned infants were less able to ferment oligosaccharides a nd complex carbohydrates than were weaned infants (P < 0.05). Ability to ferment raftilose was higher in early weaning; median total SCFA co ncentrations (mmol/L) were as follows: preweaning 31.0 (range: 3.6-48. 9), early weaning 57.1 (range: 2.5-70.6), late weaning 68.6 (range: 22 .0-113.4) (P < 0.05). Ability to ferment complex carbohydrates did not develop until late weaning; median total SCFA concentrations for guar gum (mmol/L) were as follows: preweaning 6.4 (range: 0.1-57.3), early weaning 18.4 (range: 0.0-40.5), late weaning 45.4 (range: 15.6-62.1) (P < 0.05, preweaning and early weaning compared with late weaning). D evelopment of the ability to ferment complex carbohydrate was slow. Cu ltures of feces from preweaned infants produced eight times more SCFAs with glucose than with complex carbohydrates, at early weaning there was a threefold difference and by late weaning the difference was only 25%, but this was still only 42% of the SCFAs produced by cultures of adult feces. These data suggest that for the complex carbohydrates te sted, colonic fermentation is likely to contribute only a small propor tion of daily energy needs of weaning infants.