Ability of the normal human small intestine to absorb fructose: evaluation by breath testing.
OBJECTIVE
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.
Rao
Satish S C
SS
Department of Internal Medicine and Clinical Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242-1009, USA. satish-rao@uiowa.edu
Attaluri
Ashok
A
Anderson
Leslie
L
Stumbo
Phyllis
P
D000328:Adult; D000368:Aged; D000388:Air / Q000032:analysis; D001944:Breath Tests / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D005632:Fructose / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006801:Humans; D006859:Hydrogen / Q000032:analysis; D007408:Intestinal Absorption / Q000502:physiology*; D007421:Intestine, Small / Q000378:metabolism*; D008286:Malabsorption Syndromes / Q000175:diagnosis / Q000378:metabolism; D008297:Male; D008697:Methane / Q000032:analysis; D008875:Middle Aged; D011379:Prognosis; D012016:Reference Values; D013549:Sweetening Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*
D013549:Sweetening Agents; D005632:Fructose; D006859:Hydrogen; D008697:Methane