Bioavailability of glucose from Palatinit.

For the sake of metabolic insight into the fate of the sugar substitute Palatinit, its two components D-glucosyl-alpha (1 leads to 1)-D-mannitol and D-glucosyl-alpha (1 leads to 6)-D-glucitol [D-glucosyl-alpha-(1 leads to 6)-D-sorbitol] were assayed for glucose bioavailability by the procedure of Karimzadegan et al. using ketotic rats. With conversion rates into glucose of 6 and 20%, respectively, for free mannitol and glucitol (sorbitol), 39% for glucosylmannitol and 42% for glucosylglucitol, the metabolic glucose pool of the rat does not receive the full carbohydrate complement of these compounds. The preformed glucose moiety of the glucosylhexitols is bioavailable by 36 and 32%, respectively, from glucosylmannitol and glucosylglucitol, with 50% as theoretical maximum. Less than theoretical bioavailability of glucose from Palatinit is ascribed to microbial attack in the hindgut. The data on rats are held valid also for other species demonstrating carbohydrate fermentation in the caecum and/or colon. Differences between D-glucosyl-alpha (1 leads to 1)-D-mannitol and D-glucosyl-alpha (1 leads to 6)-D-glucitol are caused by a differential delay of glucose absorption in the small intestine, also exerted by D-glucitol. The deep metabolic insight offered by the glucose bioavailability assay into the fate of carbohydrates includes the mammal-microbial symbiosis in the large bowel. Since a rather complete survey of the metabolic consequences after their intake can be obtained, the assay system should be generally applied in assessments of food safety also of other sugar substitutes.