Nov. 3, 2011 (Washington, D.C.) -- A very restricted diet that that is low in certain natural sugars may help relieve bloating, gas, abdominal pain, and other symptoms in people with irritable bowel syndrome (IBS), Australian researchers report.
Known as a low-FODMAP diet, it doesn't work for everyone. And it isn't easy to follow -- rye, wheat, and white breads and pastas, apples, watermelon, ice cream, and honey are just a few of the restricted foods.
But a number of studies, while small, have established its benefits, says Peter Gibson, MD, professor of gastroenterology at Monash University in Victoria, Australia.
In one study published earlier this year, British researchers found that more than 80% of 43 people with IBS who followed a low-FODMAP diet reported less bloating, abdominal pain, and gas. That compares with only about 50% to 60% of 39 people who stuck with standard dietary advice.
Gibson and FODMAP developer Sue Shepherd, PhD, a dietitian in Victoria, Australia, spoke about the diet at the annual meeting of the American College of Gastroenterology here. Both have written low-FODMAP cookbooks.
What Are FODMAP Foods?
Irritable bowel syndrome affects up to 55 million Americans, mostly women. Its symptoms include bloating and stomach distension, excess gas, abdominal pain, nausea, diarrhea, constipation, and fatigue.
The cause is not known, but it's generally accepted that stress and certain foods and drinks, like french fries and caffeinated beverages, can make symptoms worse in some people.
Gibson and Shepherd believe a much wider variety of foods -- namely those containing natural FODMAP sugars -- can trigger IBS symptoms.
FODMAP stands for a mouthful of words: fermentable, oligosaccharides, disaccharides, monosaccharides, and polyols.
These sugars are found in wheat, rye, onion, garlic, leeks, artichokes, mushrooms, cauliflower, snow peas, beans, chickpeas, lentils, milk products except hard cheese, honey, apples, pears, watermelon, mangos, stone fruits, high-fructose corn syrup, sorbitol, mannitol, maltitol, and xylitol. And more.
Still unknown is the long-term safety of the diet. Ongoing research is aimed at ensuring it is nutritionally adequate.
Shepherd says that shouldn't be a problem as long as the restricted foods are replaced with foods that add up to equal nutritional value.
Among the allowed foods: bananas, blueberries, grapes, oranges, tomatoes, maple syrup, gluten-free breads and cereals, rice noodles and rice, water crackers, oats, polenta, broccoli, bok choy, carrot, cucumber, green beans, sweet potato, olives, lactose-free milk, rice milk, hard cheeses, butter, margarine, and soy yogurt.
Gibson says that in one study, about three-fourths of 62 people with IBS stuck with the diet for the 14 months, on average, that they were followed. That's probably because the same number said it worked for them, he says.
In another small study, people with IBS who were switched to a high-FODMAP diet experienced increased abdominal pain, bloating, and fatigue after just two days.
Why High-FODMAP Foods Cause Symptoms
According to Shepherd, the sugars in FODMAP foods are poorly absorbed by the body and draw excess water into the gut, causing the symptoms of IBS.
So why do some people get symptoms and others don't?
Gut sensitivity, Gibson tells WebMD.
"It's an abnormal response to a stimulus. People with IBS feel even normal distension and might get changes in their bowel habits or bloating or pain," he says.
FODMAP Slowly Catching on in U.S.
University of Michigan gastroenterologist William Chey, MD, tells WebMD that the diet is slowly gathering support among U.S. health care professionals.
"It took three meetings to convince our [university] dietitian to try it," because she felt no one could stick to such a restrictive diet, he says.
"Her first patient later told her, 'It’s been an incredibly liberating experience,'" Chey says.
That could be because many people with IBS have already cut so many foods out of their diet on their own in an effort to prevent symptoms, he theorizes.
Still, the diet is complicated. You should have a thorough exam to rule out other medical conditions. And you should find a dietitian trained in low FODMAPs to ensure you follow a nutritionally sound diet, Shepherd advises.
The diet requires a big commitment from both you and your family, the experts say. Some say they would reserve it for patients whose symptoms interfere with their everyday life.