Bw. Wolf et al., VARYING DIETARY CONCENTRATIONS OF FRUCTOOLIGOSACCHARIDES AFFECT APPARENT ABSORPTION AND BALANCE OF MINERALS IN GROWING RATS, Nutrition research, 18(10), 1998, pp. 1791-1806
Carbohydrates that bypass digestion in the small intestine and are fer
mented in the large intestine may affect the absorption of certain min
erals. A study was conducted to determine the effect of varying dietar
y concentrations of fructooligosaccharides (FOS) on the apparent diges
tibility and balance of certain macro and trace minerals. Forty growin
g male Sprague-Dawley rats were assigned one of four treatments: 1) pu
rified diet (control); 2) purified diet + 1% FOS; 3) purified diet + 3
% FOS; or 4) purified diet + 5% FOS. Rats were acclimated to their met
abolic cages for 5 d, after which they were subjected to a 10-d growth
period, followed by a 7-d balance period in which diets were restrict
ed to 90% ad libitum intake of the lowest consuming rat. Cecal pH decr
eased (P < 0.01) as dietary FOS concentration increased, reflecting an
increase in cecal short-chain fatty acid concentration. In addition,
FOS supplementation increased (P < 0.01) fecal N excretion, although N
balance was similar among groups. Apparent absorption of Mg increased
linearly (P < 0.01) as FOS concentration increased in the diet; howev
er, Mg balance (mg/d) was similar (P > 0.10) across treatments. The ma
crominerals (Ca, P, Mg, Na, Cl, K) and trace minerals (Cu, Fe, Mn, Zn)
were in a positive balance for all experimental treatments. However,
Cu absorption decreased with increasing FOS concentration. This may be
explained by an increase in fecal microbial mass which would contain
a relatively significant amount of Cu or by an increase in hepatic bil
e Cu excretion. These results suggest that dietary FOS alters acute Cu
metabolism in growing rats. (C) 1998 Elsevier Science Inc.