Fructose: incomplete intestinal absorption in humans.

Fructose is an increasingly important commercial sweetener. However, some patients report abdominal symptoms after ingesting fructose-containing foods. The completeness of fructose absorption by the small intestine was assessed by breath hydrogen analysis in 16 healthy volunteers and incomplete absorption was defined as a peak rise in breath hydrogen of greater than 20 parts per million. Fructose, 50 g as a 10% solution, was incompletely absorbed in 6 of 16 subjects (37.5%). Incomplete absorption was associated with symptoms of cramps or diarrhea, or both in 5 of these 6 individuals. Incomplete absorption was both concentration- and dose-related. Three subjects incompletely absorbed 37.5 g of fructose. In comparison, all 15 subjects who were studied after ingestion of sucrose, 50 g and a 10% solution, completely absorbed this sugar load. Incomplete absorption of fructose should be considered as a possible case of gastrointestinal symptoms.