Fat, Fructose May Worsen Gastric Upset

Oct. 13, 2003 (Baltimore) -- Can avoiding certain foods help to relieve the bloating, tummy aches and general misery associated with irritable bowel syndrome?

That's the intriguing possibility raised by two new studies that show that fat and fructose, the simple sugar found in honey, fruits, and some soft drinks, may contribute to symptoms of the misunderstood gastrointestinal syndrome that affects more than 1 in 10 Americans.

The research was presented here this week at the 68th Annual Scientific Meeting of the American College of Gastroenterology.

Young K. Choi, MD, of the University of Iowa in Iowa City, studied people with irritable bowel syndrome, or IBS, whose bodies cannot absorb fructose properly.

Irritable bowel syndrome is one of the most common gastrointestinal disorders, affecting almost 58 million Americans. People who suffer from it have symptoms of abdominal discomfort or pain, and they can alternate between diarrhea and constipation.

In this study, those who were able to eliminate fruit and other fructose-rich foods from their diet were rewarded with an improvement in symptoms, Choi says.

While not as well known as lactose intolerance, fructose intolerance is quite common, affecting one-third to one-half of patients with symptoms of IBS, Choi says.

The researchers tested 80 patients with suspected IBS; 30 were found to be fructose intolerant. The patients were taught what foods are high in fructose and urged to avoid them.

After one year, interviews with 26 of the patients showed that only one-half stuck to the fructose-restricted diet, Choi says.

But those who did stick with the program reported significantly less abdominal pain, bloating, and diarrhea than before changing their diets, he says. Not surprisingly, those who cheated on their diets showed no improvement in symptoms.

Avoiding fructose is no easy task, says Kevin W. Olden, MD, associate professor of medicine in the division of gastroenterology at the Mayo Clinic in Scottsdale, Ariz. High-fructose corn syrup is a hidden ingredient in everything from cola to lemonade, he says.

Richard G. Locke III, also of the Mayo Clinic, says he wonders whether patients in the study really had IBS. Fructose intolerance can cause pain, bloating, and diarrhea -- the same symptoms associated with irritable bowel syndrome.

"We used to think people who were intolerant to milk had IBS, but now we know they have lactose intolerance," Locke says. "The same thing could be happening here. It's a matter of labeling."

The important thing is to know that fructose can cause these symptoms, says Yuri A. Saito, MD, MPH, also of the Mayo Clinic. "Most people are not even aware of this."

In the second study, Saito and colleagues in the division of gastroenterology and hepatology found that people with IBS tend to reach for high-fat, low-carb foods. These dietary factors may contribute to some of the symptoms suffered by gastrointestinal disorders such as IBS.