Nutritional assessment in humans and rats of leucrose [D-glucopyranosyl-alpha(1----5)-D-fructopyranose] as a sugar substitute.

Leucrose [D-glucosyl-alpha(1----5)-D-fructopyranose], prepared by an enzyme-catalyzed transglycosidation from sucrose with greater than 99% purity, has previously been shown to be noncariogenic and was found in the present study to be apparently easily digestible when given to humans as a single oral dose of 100 g, or when fed to rats at a level of 35 g/kg body wt daily. Weanling rats fed a 25% leucrose diet grew as well as rats fed a diet containing 25% sucrose or corn starch. When 1 g of leucrose was given intravenously to adult rats, 70% of this disaccharide was excreted in the urine within 24 h, and feeding and drinking behavior of the rats was not altered. No adverse effects on their general health were observed. The substrate properties of leucrose for alpha-glucosidase from yeast and for carbohydrases from human jejunal mucosa were determined, and these data were then compared with those of maltose and sucrose. The cleavage rate of leucrose in vitro by human digestive carbohydrases was 31% that of maltose and 63% that of sucrose. Hydrogenated leucrose (leucritol) was cleaved 10 times slower, with a Michaelis constant close to that of leucrose. Blood glucose and fructose profiles in humans given leucrose per os tended to be lower than those in humans given sucrose, while insulin and C-peptide profiles were unaltered.