Fructose Consumption Is on the Rise, So Are Digestive Problems

We're a nation consuming ever-greater quantities of sweets - and we're suffering from an epidemic of gastrointestinal distress.

It turns out the two could be related.

Satish Rao, a gastroenterologist at the University of Iowa medical school, was puzzled a few years ago by the many patients coming to his clinic with abdominal pain, bloating, gas and diarrhea that seemed to defy explanation.

Rao suspected fructose, a form of sugar that occurs naturally in fruit. Americans' consumption of fructose, mostly in the form of high-fructose corn syrup, has skyrocketed. The U.S. Department of Agriculture reports that between 1970 and 1997, average annual per capita consumption increased from half a pound to 62.4 pounds. The vast majority of that is contained in soft drinks, although it's also added to a variety of processed and baked foods.

The problem with fructose is that humans aren't well equipped to digest it. Most people can handle a small amount, but given the increasing consumption of fructose, Rao theorized that people might be overwhelming their intestines' ability to break down the stuff.

The result: pain, gas, diarrhea. Those are the primary features of irritable bowel syndrome, or IBS, a condition that's thought to affect perhaps 15 percent of Americans, Rao said.

He administered a fructose solution to a group of patients, then used a simple test to measure the fructose in their breath. He found that 30 percent of the patients with IBS symptoms had fructose in their breath, meaning they hadn't digested it.

Then Rao advised those with positive fructose tests to curb their fructose consumption.

Those who complied with the diet felt significantly better, he said.

He concluded that most people cannot adequately digest more than about 25 grams of fructose. A can of regular Coke contains 16 grams, he said, and a glass of orange juice has 15 grams.

So the two of those consumed within a span of a couple of hours can overwhelm a person's ability to handle fructose, he said. People with a tendency toward gastrointestinal complaints are more likely than others to suffer from eating or drinking too much fructose.

The supersizing of food and drink has certainly contributed to fructose-related gastrointestinal problems, said Pete Beyer, an associate professor of dietetics and nutrition at the University of Kansas Medical Center.

"When I was a kid, a 4-ounce glass was the serving size of juice," he said. "Now you can go to a service station and get a 20-ounce serving of juice."

Beyer also conducted fructose breath tests on a group of people who didn't report any gastrointestinal symptoms. After having consumed a fructose solution, the vast majority of subjects tested positive for fructose in their breath, meaning they weren't digesting it all, he said.

While the problems stemming from fructose aren't on a par with diabetes or cancer, Beyer said it's becoming clear "that the doses (people) can get in everyday life can cause problems in average everyday people."

And for those people, he said, a diet lower in fructose could make all the difference.

---

(c) 2003, The Kansas City Star. Distributed by Knight Ridder/Tribune News Service.