Fructose malabsorption: how much fructose can a healthy subject tolerate?

BACKGROUND/AIMS: In a prospective study, we evaluated fructose absorption capacity in 17 healthy female volunteers aged 16-27 years. METHODS: All volunteers underwent analysis of their daily food intake diary and standardized breath tests. The volunteers were challenged consecutively with oral intake of 50, 25 and 15 g of fructose. RESULTS: The average daily ingestion of fructose (19.54 ± 14.95 g) was not different between volunteers with positive and negative breath tests. On day 1, 53% of subjects exhibited a significant (≥20 ppm) increase in breath hydrogen and gastrointestinal symptoms upon challenge with 50 g of fructose. Moreover, 37.5% of the volunteers with a negative breath test became positive upon a second challenge with 50 g of fructose but remained asymptomatic. On day 2, 1 of the 9 volunteers (12.5%) with a positive breath test on day 1 exhibited an asymptomatic positive breath test upon exposure to 25 and 15 g of fructose on day 3. The 8 volunteers with a negative test (25 g of fructose) remained negative after a second exposure to 25 g of fructose. CONCLUSION: The results of this study indicate that hydrogen breath tests with fructose challenge of 50 g of fructose are inappropriate to characterize clinically significant fructose malabsorption.