In a randomized trial, people with irritable bowel syndrome with diarrhea (IBS-D) had significant pain and symptom relief on a diet that starves gut bacteria of some of their favorite foods, according to a new study.
The “low FODMAP” diet restricts foods that are high in fermentable oligo-, di- and monosaccharides and polyols (FODMAPs), short-chain carbohydrates that are poorly absorbed in the gut but quickly fermented by intestinal bacteria. Fermentation produces gas and excess liquid, and may underlie the symptoms of IBS.
Researchers are not sure why people with irritable bowel syndrome are sensitive to the family of FODMAP carbohydrates.
Ten to 15 percent of U.S. adults may have irritable bowel syndrome (IBS), symptoms of abdominal pain and changes in bowel movement patterns usually marked by either diarrhea or constipation. The condition is most common in women and people under age 45. Diet modifications, medication, probiotics and mental healthcare can help treat the symptoms.
Current guidelines include avoiding trigger foods and keeping a regular meal schedule, but these recommendations are not evidence-based and often ineffective.
The low FODMAP diet
FODMAPs are fructose (in fruit), lactose (milk), fructans (wheat, garlic, onion), galactans (beans, lentils, soybeans) and polyols (sweeteners containing sorbitol, mannitol and xylitol). Foods high in FODMAPs include barley, yogurt, apples, apricots, blackberries, pears, artichokes, cauliflower, mushrooms, pistachio nuts, cashews, honey and agave nectar. And more.
The low FODMAP diet involves eliminating high FODMAP foods (see chart, below) for six to eight weeks. If FODMAPs trigger symptoms, noticeable improvement can occur in just a few days.
After the elimination period, high FODMAP foods are slowly added back in one at a time, in correct portions, to determine which ones are well tolerated. The goal: to find as varied a diet as possible that keeps IBS symptoms at bay.
About the study
The researchers compared one group of patients with IBS-D on a low FODMAP diet to a group following dietary recommendations for IBS based on modified guidance from the National Institute for Health and Care Excellence (mNICE). The mNICE group was instructed to eat small frequent meals, avoid trigger foods like wheat products and starches, limit fresh fruit, avoid the artificial sweetener sorbitol and avoid excess alcohol and caffeine.
For the four-week study, patients modified their diets to one of the two options and rated whether their overall IBS symptoms had been adequately relieved for at least half of the final two weeks of the study.
Of the 92 people randomized into the trial, 84 completed the four-week diet period. Among participants on the low FODMAP diet, 52 percent experienced adequate relief in the last two weeks, compared to 41 percent of the mNICE dieters.
Compared to scores rating abdominal pain, bloating, consistency of stool, frequency and urgency at the beginning of the study, the low FODMAP diet led to greater reductions in average daily scores than the mNICE diet.
Some people do very well on the low FODMAP diet and more dietitians and doctors are adding it to their list of treatment options.
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