Fm. Larsen et al., DIETARY FIBER VISCOSITY AND ENDOGENOUS PROTEIN EXCRETION AT THE TERMINAL ILEUM OF GROWING RATS, The Journal of nutrition, 123(11), 1993, pp. 1898-1904
The effect of dietary fiber viscosity on the excretion of endogenous n
itrogen and amino acids from the small intestinal lumen of growing rat
s was investigated. Rats were fed for 12 d protein-free diets containi
ng 5% cellulose (negligible viscosity) or 5% carboxymethylcellulose of
low (20 cP), medium (800 cP) or high (2000 cP) viscosity, as the sole
dietary fiber source. As dietary fiber viscosity increased from 0 to
2000 cP, there was a significant (P < 0.05) linear increase in the flo
w of endogenous nitrogen, aspartic acid, serine, glutamic acid, prolin
e, threonine, glycine, alanine, isoleucine, histidine, valine, methion
ine, leucine and lysine at the terminal ileum. The amino acid composit
ion of the ileal digesta was unaffected by changes in fiber viscosity.
It seems that either endogenous protein of a similar origin was secre
ted in larger amounts or that the digestion and absorption of endogeno
us amino acids was inhibited as dietary fiber viscosity increased. The
re was a significant (P < 0.05) linear increase in the concentration o
f sialic acids relative to chromic oxide in the small intestinal conte
nts with increasing fiber viscosity, indicating an increase in mucopro
teins.