Ileal loss of available carbohydrate in man: comparison of a breath hydrogen method with direct measurement using a human ileostomy model.

The breath hydrogen technique has suggested that a considerable amount of available plus unavailable carbohydrate enters the large intestine after the consumption of starchy foods (white bread 11%, wholemeal bread 8%, and red lentils 18%). Direct measurement of the available carbohydrate in ileal effluent after the consumption of test meals by three individuals with ileostomies gave values similar to those determined by the breath hydrogen technique (white bread 10%, wholemeal bread 8%, and red lentils 22%). These studies confirm that considerable amounts of "available carbohydrate" may be lost to the small intestine and physiologically must be considered as dietary fiber. The implications of this with respect to metabolism and colonic disease remain to be investigated.