Sorbitol is a commonly used sugar substitute in "sugar-free" food products. Although sorbitol intolerance manifested by abdominal pain, bloating, and diarrhea has been observed in children, it has not been well documented in adults. Forty-two healthy adults (23 whites, 19 nonwhites) participated in this study. After ingestion of 10 g of sorbitol solution, end expiratory breath samples were collected at 15-min intervals for 4 h and analyzed for H2 concentration. Clinical sorbitol intolerance was detected in 43% of the whites and 55% of the nonwhites, the difference not being statistically significant. However, severe clinical sorbitol intolerance was significantly more prevalent in nonwhites (32%) as compared to whites (4%). There was a good correlation between the severity of symptoms and the amount of hydrogen exhaled. Dietetic foods, many of them containing sorbitol, are very popular with diabetics and "weight watchers." Based on our observations, we believe that a large number of adults could be suffering from sorbitol-induced nonspecific abdominal symptoms and diarrhea. These symptoms could lead to an extensive diagnostic work-up and lifelong diagnosis of irritable bowel syndrome.