As many as 20% of adults at some point suffer from a painful digestive disorder that is difficult to diagnose and has no cure. Treatment is hit or miss, and many sufferers never seek help because they find the symptoms hard to discuss.

Irritable bowel syndrome (IBS) has long baffled gastro-intestinal experts. Some think it is caused by imbalances in gut bacteria; others point to psychological stress. Now, a small but growing contingent of specialists is focusing on food intolerances as a possible culprit—and a new dietary approach, called the low-Fodmaps diet, is gaining attention around the world.

The theory is that many people with IBS have trouble absorbing certain carbohydrates in their small intestines. Large molecules of those foods travel to the colon, where they are attacked by bacteria and ferment, creating the telltale IBS symptoms of gas, bloating, constipation or diarrhea.

A long list of foods—including dairy products, some fruits and vegetables, wheat, rye, corn syrup and artificial sweeteners—can potentially create such problems in susceptible people. Collectively, they’re known as Fodmaps, an acronym that for stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols.

Physicians have long known that some of these foods can cause stomach upset individually. About 15% of American lack an enzyme needed to digest lactose, a sugar found in milk products. There’s now growing awareness that foods with a high concentration of fructose can be difficult to absorb. Breath tests that measure gas produced in the intestine can diagnose both of those issues, although they are more common in Australia than in the U.S.

Three other categories of sugars have also been found to cause absorption and fermentation problems in some people—including fructans that are found in wheat and rye, galactans that are found in legumes, and polyols, found in some fruits and in artificial sweeteners such as sorbitol and mannitol.

In fact, some experts say it’s possible that people who do not have celiac disease but still have trouble digesting wheat products may actually be sensitive to the fructans in wheat rather than the gluten, which is protein component.

The low-Fodmaps diet recommends eliminating all of those foods for a period of six to eight weeks, and then gradually adding back one group after another to identify which cause the most trouble.

Eventually, many IBS sufferers find they can tolerate many foods on the list as long as they keep the total amount of Fodmaps under a certain level.

“It’s not like having celiac disease, where people can’t ever eat gluten,” says Sue Shepherd, a dietician in Victoria, Australia, who developed the diet in 2001 mainly for patients with lactose or fructose intolerance, but found it worked well with IBS sufferers as well.

Small studies in Australia and the U.K. have shown that the diet reduces symptoms in about 75% of IBS sufferers—higher than other diet or medication approaches. In one study, published in the Journal of Human Nutrition and Dietetics last month, researchers at Kings College in London compared 43 IBS patients on the low-Fodmap diet with 39 given standard diet advice such as limiting caffeine and carbonated beverages. More than 80% of those in the low-Fodmap group reported less bloating and less abdominal pain compared with about half in the control group.

Although the low-Fodmaps diet is still relatively unknown in the U.S., a presentation on it drew a rapt audience at the American College of Gastroenterology conference in Washington last week. Word is also spreading among IBS patient groups.

“Many people who have tried it say they can’t believe how much it’s changed their lives,” says Jeffrey D. Roberts, who founded an online support community at that has 45,000 members.

“I was in a lot of pain and I didn’t know what caused it,” says Sarah Wade, 28, a paramedic in Melbourne who was diagnosed with IBS as a teenager. She was referred to Dr. Shepherd after a breath test—common in Australia but less known in the U.S.—indicated that she was fructose intolerant. Learning what she can and can’t eat on the diet has alleviated her symptoms for the first time in years, she says. “Apples, pears and onions, I avoid at all costs. Artificial sweeteners, too. But the pain is gone, and I’m eating healthier than I’ve ever eaten before.”

Rocky Parthenopoulos, 57 and also from Melbourne, struggled for decades with severe symptoms and, like many IBS sufferers, was told it was all in his mind. “I tried various laxatives, diets, exercise, vitamins supplements and alternative medicines, all to no avail,” he says. “I had barium enema, colonoscopies, endoscopies, food-allergy tests, but was told l was healthy and normal.”

After losing his job in the tech industry, he found a clinic that worked with Dr. Shepherd and tested positive for both lactose and fructose intolerance. He found that at first, the low-Fodmaps diet was difficult to follow, since many foods on the list are common ingredients in processed foods. “There are many temptations to cheat,” he says. But once he learned it, he says, his symptoms have gone from “an 8 or 9 out of 10 to 1 or 2. “It’s turned my life around,” he says.

The low-Fodmaps diet has “changed our practice enormously,” says Peter Gibson, a professor of gastroenterology at Monash University in Victoria who noticed how well IBS patients fared on Ms. Shepherd’s diet and encouraged her to pursue a doctorate testing it in clinical trials. One of the biggest pluses, he finds, “is that it puts people in control of what they need to avoid to manage their symptoms. It’s not the doctor saying, ‘You can’t have this or that.’ ”

The Fodmaps approach is gaining fans among U.S. gastroenterologists as well, even though many have been skeptical of diets in the past.

William Chey, director of the Gastrointestinal Physiology Laboratory at the University of Michigan Health System, first tried the diet with IBS patients three years ago.

“This Fodmap approach doesn’t make everybody better, but it makes a lot of people significantly better,” says Dr. Chey, who is also co-editor-in-chief of the American Journal of Gastroenterology. He is now helping to design large-scale clinical trials of the diet for the U.S.

For now, he and other experts say that because so many foods have Fodmap components and that reintroducing them can be tricky, IBS sufferers shouldn’t try the diet on their own. But a growing number of dieticians are being trained in it— has started a registry—and academic medical centers are starting to offer it, too.

GI doctors can also rule out more serious causes of symptoms, such as celiac disease, inflammatory bowel disease or colon cancer.

“We’ve been missing the boat in not recognizing the role of foods in functional GI disorders,” Dr. Chey says. “We’ll see much more attention to this in the next few years.”

Story Source:

The above story is reprinted from Wall Street Journal Health Journal, Nov 8, 2011. When Everyday Foods Are Hard to Digest GI Specialists Suspect Specific Carbohydrates May Cause Painful Symptoms of Irritable Bowel Syndrome by Melinda Beck

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