Original article—alimentary tract
Ability of the Normal Human Small Intestine to Absorb Fructose: Evaluation by Breath Testing

Portions of this work were presented at the Digestive Disease Week 2003, May 17-22, Orlando, Florida and published as an abstract in Gastroenterology 2003;124:312.
https://doi.org/10.1016/j.cgh.2007.04.008Get rights and content

Background & Aims: Fructose consumption is increasing, and its malabsorption causes common gastrointestinal symptoms. Because its absorption capacity is poorly understood, there is no standard method of assessing fructose absorption. We performed a dose-response study of fructose absorption in healthy subjects to develop a breath test to distinguish normal from abnormal fructose absorption capacity. Methods: In a double-blind study, 20 healthy subjects received 10% solutions of 15, 25, and 50 g of fructose and 33% solution of 50-g fructose on 4 separate days at weekly intervals. Breath samples were assessed for hydrogen (H2) and methane (CH4) during a period of 5 hours, and symptoms were recorded. Results: No subject tested positive with 15 g. Two (10%) tested positive with 25 g fructose but were asymptomatic. Sixteen (80%) tested positive with 50 g (10% solution), and 11 (55%) had symptoms. Breath H2 was elevated in 13 (65%), CH4 in 1 (5%), and both in 2 (10%). Twelve (60%) tested positive with 50 g (33% solution), and 9 (45%) experienced symptoms. The area under the curve for H2 and CH4 was higher (P < .01) with 50 g compared with lower doses. There were no gender differences. Conclusions: Healthy subjects have the capacity to absorb up to 25 g fructose, whereas many exhibit malabsorption and intolerance with 50 g fructose. Hence, we recommend 25 g as the dose for testing subjects with suspected fructose malabsorption. Breath samples measured for H2 and CH4 concentration at 30-minute intervals and for 3 hours will detect most subjects with fructose malabsorption.

Section snippets

Methods

Healthy volunteers with no previous history of gastrointestinal disorders or surgeries, antibiotic use (within 3 months), and who were not taking any medications (except oral contraceptive pills or multivitamins) were recruited through a hospital advertisement. They were asked to fill out a health symptom questionnaire and undergo a routine physical examination. Only subjects who were asymptomatic fulfilled the aforementioned inclusion criteria, and had a normal physical examination were

Results

Twenty subjects (male/female, 10/10; mean age, 31 years; range, 19 to 70 years) participated in the study.

Discussion

The capacity of the human small intestine to absorb fructose is unclear. Some studies have suggested that healthy humans malabsorb fructose at doses as low as 5 g,5 although others have found malabsorption at doses of 37.5 g or higher.8 Consequently, the assessment of dietary fructose malabsorption has remained problematic.2 Our objectives were to examine fructose absorption in healthy subjects and to facilitate the development of a breath test that can be used in patients with suspected

References (20)

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Supported in part by NIH grant RO1 DK 57100-05 and grant RR00059 from the General Clinical Research Centers Program, National Center for Research Resources.

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