Sandra Yin

November 02, 2011

November 2, 2011 (National Harbor/Washington, DC) — A diet that is low in certain natural sugars can reduce symptoms in patients with certain gut disorders, including irritable bowel syndrome (IBS). That is the message that Peter Gibson, MD, head of the Eastern Clinical School at Monash University in Victoria, Australia, shared at this year's American Journal of Gastroenterology lecture here at American College of Gastroenterology 2011 Annual Scientific Meeting and Postgraduate Course.

His talk — Food Choice as a Key Management Strategy for Functional Gastrointestinal Symptoms — addressed how certain food components can induce or trigger functional gut symptoms, and examined how avoiding those food components can lead to a global improvement in symptoms in patients with functional bowel disorders, including IBS.

If we can recognize what dietary components contribute to problems and reduce their intake, hypothetically, that should reduce symptoms, Dr. Gibson told the packed audience.

Dr. Gibson, who is a proponent and cofounder of a low-FODMAP diet, claims that poorly absorbed short-chain carbohydrates, which are small molecules that are potentially osmotically active and rapidly fermentable, are to blame for gut symptoms such as bloating, wind, abdominal pain, and changes in bowel habits.

FODMAP stands for fermentable, oligosaccharides (including the fructo-oligosaccharides found in wheat, rye, onion, garlic, leeks, and artichokes, and the galacto-oligosaccharides found in beans, chick peas, and lentils), disaccharides (milk products except hard cheese), monosaccharides (excess fructose, fruits that contain more fructose than glucose, honey, apples, pears, mangos, high-fructose corn syrup), and polyols (sugar alcohols including sorbitol, mannitol, stone fruits, apples and pears, mushrooms, cauliflower, snow peas, maltitol, and xylitol).

A number of studies have established the benefits of a low-FODMAP diet for certain patients, Dr. Gibson said. In one study, after just 2 days, patients with IBS who were placed on a high-FODMAP diet experienced increased abdominal pain, bloating, and tiredness.

In another study, patients randomized to a low-FODMAP diet, as opposed to a standard diet, for IBS experienced a marked improvement in symptoms overall.

Patients have long blamed food for their functional gut symptoms, but gastroenterologists have not shown much interest in dietary therapy. "It's out of our comfort zone to deal specifically with food issues," Dr. Gibson explained.

General skepticism about actual food allergy and intolerance hasn't helped. Nor has the lack of a reliable test to identify trigger foods. The only way to validate a food intolerance is an elimination diet and a "rechallenge," which is tedious. But change is afoot. "Food is now sexy, and I think it's time for us all to engage," Dr. Gibson said.

The low-FODMAP diet is based on several concepts. First, major functional gut symptoms originate from the gut, where the enteric nervous system controls functions such as secretion, blood flow, and mucosal growth. Low-intensity stimuli have little effect on motility; high-intensity stimuli can alter motility and lead to pain and discomfort.

Food can induce luminal distention, which usually does not pose a problem, but it can in patients with IBS. If someone eats a big meal of onions, fat, and lentils, which has an abnormally large amount of "high-stimulus" food components, it can lead to bloating and diarrhea. If we can recognize the dietary components that trigger certain effects and then reduce their intake, Dr. Gibson said, we should be able to reduce symptoms.

During a press briefing, he noted that in Australia, the low-FODMAP diet has changed the way they manage IBS and other conditions. such as bloating or changed bowel habits. Drugs are used less frequently, and more than 100 gastrointestinal dieticians work in Melbourne alone, he said.

"I think one of the major positives is that not only do 3 of 4 patients improve, [the diet] is sustainable," said dietician Sue Shepherd, PhD, who runs a private practice in Victoria Hill, Australia, called Shepherd Works. She designed an early version of the low-FODMAP diet. Some patients have stayed on the diet for 11 years and counting.

When Dr. Shepherd developed the diet, people laughed at her, she said, and doctors stopped giving her referrals. She started working with Dr. Gibson at a hospital as the dietician for outpatients. All the patients who had been frequent flyers at their clinic were saying that they didn't need to return because they were feeling better, she explained; "it was a great sign that the diet worked." Word of mouth spread among patient groups. "As soon as they realize that it works, patients stick with it."

People are far less aware of the diet in the United States. At an ACG course in Virginia, before a presentation on FODMAP, William Chey, MD, FACG, who is professor of medicine and codirector of the Michigan Bowel Control Program at the University of Michigan Medical Center in Ann Arbor, polled 400 gastroenterologists to see how many had heard of the low-FODMAP diet, which he has worked with for 2 to 3 years. About 20 hands went up.

"I think doctors, just like patients [with functional GI disorders], are absolutely — no pun intended — hungry for nonmedical interventions," he said. "We just don't know what they are."

Dr. Gibson and Dr. Shepherd have disclosed no relevant financial relationships. Dr. Chey reports financial relationships with AstraZeneca, Axcan, Procter & Gamble, and Takeda.

American College of Gastroenterology (ACG) 2011 Annual Scientific Meeting and Postgraduate Course. Presented October 31, 2011.


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