Which Short-Chain Carbs Are the Villains in IBS?
Researchers challenged IBS patients with dietary fructose, fructans, and glucose.
Malabsorption of fructose and other short-chain carbohydrates is thought to produce symptoms of irritable bowel syndrome (IBS). Common dietary sources of fructose include fruits, honey, and high-fructose corn syrup. Some carbohydrates, such as fructo-oligosaccharides (fructans) and galactosaccharides (e.g., raffinose), cannot be absorbed by humans.
Now, in a double-blind, randomized, crossover trial, researchers have assessed the effects of fructose and fructans (alone or in combination) as dietary triggers of IBS symptoms. Twenty-five patients with known fructose malabsorption were challenged by graded-dose introduction of fructose, fructans, the combination, or a glucose control administered as drinks with meals for a 2-week test period, followed by a 10-day washout period.
In a dose-dependent manner, fructose reproduced IBS symptoms in 70% of patients, fructans reproduced symptoms in 77%, and the combination induced symptoms in 79%. Only 14% of those challenged with glucose showed IBS symptoms (P
0.002).
Comment: Up to 40% of patients with IBS have been shown to absorb fructose incompletely (JW Gastroenterol Sep 28 2007). In this study, IBS symptoms were induced by either fructose or fructans, indicating that symptoms are reproduced by the bowel’s response to delivery of undigested carbohydrates to the colon and distal small bowel. These data supply more evidence to suggest that carbohydrate malabsorption plays a role in the pathogenesis of IBS symptoms.
Published in Journal Watch Gastroenterology August 28, 2008
