Cutting back on sugar and fat makes sense for people trying to control their weight, but there may be another health benefit. Two studies suggest that fat and fructose, the sugar in fruits and honey, also can contribute to gastrointestinal discomfort.

Irritable bowel syndrome (IBS) is a common disorder of the intestines that leads to pain, gassiness, bloating and changes in bowel habits, according to the American Gastroenterological Association. The disorder can lead to constipation in some and diarrhea in others. Some people experience both. Another common symptom may be a crampy urge to move the bowels.

In the first report, Nancy Kraft, a clinical dietitian from the University of Iowa, and her colleagues say some patients who have IBS are fructose-intolerant, and restricting that type of sugar can improve their symptoms.

Kraft says fructose intolerance often is an overlooked component of IBS.

Her colleague Dr. Young Choi says that, "a fructose-restricted diet significantly improved symptoms in patients with IBS and fructose intolerance. Fructose intolerance is yet another piece of the IBS puzzle.”


In the study, the 14 patients with IBS who followed a fructose-free diet for one year experienced a significant reduction in abdominal pain, bloating and diarrhea.

However, IBS symptoms remained the same for the 12 patients who did not stick with the diet, the researchers report.

Kraft believes these results are encouraging, because "people who limit their intake of fructose see their symptoms improve or disappear," but that further study is needed.


Researchers from the Mayo Clinic in Rochester, Minnesota, led by Dr. Yuri Saito, collected data on the diets of 221 adults, aged 20 to 50 years. Of these patients, 102 had gastrointestinal disorders and 119 were healthy.

The research team found that patients with IBS or dyspepsia (indigestion) reported eating more monounsaturated fats compared with healthy patients. These patients also ate fewer carbohydrates than their healthy counterparts.

The Mayo investigators concluded that "future studies are needed to determine whether fat intake causes gastrointestinal symptoms."

Dr. Theodore M. Bayless, a professor of medicine at Johns Hopkins University, is not surprised that fat and fructose are linked with IBS and dyspepsia.

He notes that both fat and fructose are hard to digest and can aggravate both conditions. But Bayless does not believe that restricting fructose cures IBS; it may only relieve symptoms.

He advises his patients to avoid fatty foods and foods that contain high levels of fructose, such as grapes, dates, nuts, honey and apple and pear juice. He also advises patients to increase fiber intake.

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