Effects of Taiwanese yam (Dioscorea alata L. cv. Tainung No. 2) on the mucosal hydrolase activities and lipid metabolism in Balb/c mice

To investigate effects of a Taiwanese yam, Dioscorea alata L. cv. Tainung No. 2, on the mucosal enzyme activities in the small intestine and lipid metabolism, adult Balb/c mice were randomly allocated to consume control, or diets containing 25% or 50% of raw lyophilized yam (w/w) for 21 d. The leucine-aminopeptidase activity in the small intestine was increased for 79% and 102% with 25% and 50% yam diet, respectively. In contrast, the sucrase activities were decreased by both yam diets. The 50% yam diet consistently improved cholesterol profile in the plasma and liver. In agreement with that, fecal excretions of neutral steroid and bile acids were increased and fat absorption was decreased in mice fed on 50% yam diet. In conclusion, 25% yam diet was sufficient to modulate intestinal enzyme activities, but not the plasma and hepatic cholesterol levels. The reducing effects of 50% yam diet on the plasma and hepatic cholesterol levels could be mediated through the inflated fecal fat and steroid excretion.