IOWA CITY, IOWA. Fructose corn syrup is increasingly used as a sweetener in sodas, fruit juices, and candy, and fructose itself is naturally present in apples, pears, peaches and oranges. Unlike glucose, which is readily absorbed by the body, the capacity for absorbing fructose is limited. Unabsorbed fructose can draw fluid into the small intestine leading to abdominal pain and bloating. Unabsorbed fructose arriving in the large intestine (colon) is likely to ferment with resulting excessive production of hydrogen, methane, and other gases. This again may lead to bloating, flatulence and diarrhea.
Researchers at the University Iowa now report that an inability to absorb fructose (fructose intolerance) may be the root cause of many persistent, unexplained, nonspecific gastrointestinal (GI) problems. Their study involved 183 patients with unexplained, nonspecific GI problems. The most common symptoms among the patients were flatulence, abdominal pain, bloating, belching, and occasional diarrhea. All patients underwent a fructose breath test involving ingestion of 50 g of fructose in 150 ml of water followed by the measurement of hydrogen and methane in the breath. Seventy-three per cent had a positive result indicating the presence of unabsorbed fructose.
In another series of tests 89 patients with unexplained GI problems were given various concentrations of fructose solutions to see if this would reproduce their GI symptoms. The symptoms were reproduced in 88% of patients given a 33% fructose solution (50 g in 150 ml water) and 80% of these patients tested positive in the fructose breath test.
The researchers conclude that a significant proportion of patients with unexplained, nonspecific GI problems
may actually suffer from a fructose intolerance. They emphasize that fructose intolerance must be excluded
through appropriate testing before patients are assigned the catch-all designation of irritable bowel
syndrome. Fructose intolerance is relatively easily managed by simply excluding fructose from the diet
whereas irritable bowel syndrome is much more difficult to treat.