Digestion of polysaccharides of potato in the small intestine of man.

Digestion and absorption from the small intestine of starch and nonstarch polysaccharides (NSP) (dietary fiber) from potato cooked and treated in various ways have been studied in ileostomy subjects. Test meals (300 g) of potato were fed following 24 h on a plant polysaccharide-free diet. Regardless of the treatment the potato had received, greater than 90% of NSP was recovered in ileostomy effluent. Starch from freshly cooked potato was well digested, only 3% being recovered; however, 12% from cooked and cooled potato escaped digestion in the small intestine. Digestibility of starch made resistant to alpha-amylase by cooling improved on reheating. Overall, 9, 18, and 14% of total carbohydrate fed was recovered from freshly cooked, cooled, and reheated potato, respectively. Digestibility of cooled potato was identical when eaten as large lumps or as finely sieved potato. In vitro studies with pancreatin also demonstrated incomplete digestion of cooled potato.