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SAN DIEGO -- Patients with diarrhea-predominant irritable bowel syndrome (IBS) who avoided foods high in FODMAPs -- fermentable oligo-, di-, and monosaccharides and polyols -- felt better and had less abdominal pain and bloating in a randomized trial, researchers reported here.

Patients assigned to the low-FODMAP diet showed a 10-point improvement in scores on a 100-point quality of life index for IBS patients (IBS-QOL) after 4 weeks, whereas patients assigned to another diet often recommended for IBS patients that avoids “trigger foods” and involves small but frequent meals showed a slight decrease in scores (P=0.0015), reported , of the University of Michigan in Ann Arbor.

Some 52% of patients in the low-FODMAP group showed a clinically meaningful improvement, defined as a 14-point increase in IBS-QOL scores, compared with 21% of the control group, she added in an oral presentation at the .

Scores for abdominal pain and bloating and reports of stool frequency also showed improvements from baseline that were significantly greater than for controls, she said. On the other hand, the low-FODMAP diet showed no advantage for stool consistency or urgency.

In a press briefing at which the study was discussed, , of the University of Massachusetts Medical Center in Worcester, said IBS ought to be amenable to such an intervention.

The condition is "vastly shaped by diet," she said, and a role for FODMAPs in triggering or worsening IBS appears now to be well validated.

FODMAPs are thought to contribute to IBS through both osmotic and fermentation effects, Eswaran explained. Through interactions with intestinal microbiome, they are converted into gas that leads to pain and bloating, and the osmotic effects alter stool consistency and movement through the bowel.

Foods high in FODMAPs include gluten-rich grains, high-lactose dairy products, many types of legumes, and certain fruits and vegetables. But although the low-FODMAP diet avoids gluten, Eswaran emphasized that lack of gluten is no guarantee of being low in FODMAPs.

For the trial, Eswaran and colleagues enrolled 92 patients, randomizing them to the low-FODMAP diet or to the control diet, which was a modified version of a diet recommended by Britain's National Institute for Health and Care Excellence.

Patients were predominantly women in their 30s and 40s. Mean IBS-QOL scores at baseline were about 54 on the 100-point scale. They met with a dietitian who provided recipes and other instruction on the assigned diets. At the end of the 4-week intervention period, participants completed a 3-day food diary, which the investigators used to assess adherence and to estimate nutrient and energy intake values.

These latter data indicated that patients, on the whole, had complied well with the diets. Nutrient and caloric intakes were generally consistent with the dietary guidelines.

The overall improvement in IBS-QOL scores was not driven by any particular subdomains, Eswaran noted.

The researchers also administered the Hospital Anxiety and Depression Scale to evaluate participants' psychological status. For both anxiety and depression, the low-FODMAP diet was associated with significant improvements from baseline. The improvements were greater than in the control group for anxiety but not for depression.

Finally, the low-FODMAP diet appeared to reduce activity impairment associated with IBS, but no effects on workplace productivity (absenteeism and "presenteeism") were seen.