Sorbitol, a polyalcohol sugar, is the sweetener in most "sugar-free" products and may produce an osmotic diarrhea if ingested in large amounts (20-50 g). Whether or not smaller amounts of ingested sorbitol may be associated with other symptoms characteristic of carbohydrate malabsorption has not been determined. Using breath hydrogen analysis, the absorption of 5, 10, and 20 g of sorbitol was studied in 7 healthy volunteers. In a majority of subjects, ingestion of as little as 5 g sorbitol was associated with a significant increase in breath hydrogen concentration. Most subjects experienced mild gastrointestinal distress (gas, bloating) after 10 g and severe symptoms (cramps, diarrhea) after 20 g. These data suggest that the evaluation of patients with "functional" gastrointestinal complaints should include careful inquiry into the use of products containing sorbitol.