October 19, 2016
The American Journal of Gastroenterology
TAKE-HOME MESSAGE
- Patients with irritable bowel syndrome with diarrhea (IBS-D) were randomized to 4 weeks of either a diet low in fermentable oligo-, di-, and monosaccharides and polyols (FODMaPs) or a diet based on the modified National Institute for Health and Care Excellence guidelines (mNICE). Adequate relief of IBS-D symptoms was reported by 53% of those on the low FODMaP diet vs 41% of the mNICE group (P = .13). There was no difference between the two groups for the composite secondary endpoint of reduced abdominal pain and improved stool consistency. However, there were significantly more abdominal pain responders in the low-FODMaP group compared with the mNICE group (51% vs 23%; P = .008). The low-FODMaP diet had a greater impact on average daily scores of abdominal pain, bloating, consistency, frequency, and urgency than the mNICE diet.
- Adequate relief of IBS-D symptoms was obtained by 40% to 50% of adults with either the low-FODMaP diet or the mNICE diet. Individuals on the FODMaP diet reported greater improvement in individual symptoms than those on the mNICE diet.
Abstract
OBJECTIVES
There has been an increasing interest in the role of fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs) in irritable bowel syndrome (IBS). We report results from the first randomized controlled trial of the low FODMAP diet in US adults with IBS and diarrhea (IBS-D). The objectives were to compare the efficacy of the low FODMAP diet vs. a diet based upon modified National Institute for Health and Care Excellence guidelines (mNICE) on overall and individual symptoms in IBS-D patients.
METHODS
This was a single-center, randomized-controlled trial of adult patients with IBS-D (Rome III) which compared 2 diet interventions. After a 2-week screening period, eligible patients were randomized to a low FODMAP or mNICE diet for 4 weeks. The primary end point was the proportion of patients reporting adequate relief of IBS-D symptoms ≥50% of intervention weeks 3-4. Secondary outcomes included a composite end point which required response in both abdominal pain (≥30% reduction in mean daily pain score compared with baseline) and stool consistency (decrease in mean daily Bristol Stool Form of ≥1 compared with baseline), abdominal pain and stool consistency responders, and other key individual IBS symptoms assessed using daily questionnaires.
RESULTS
After screening, 92 subjects (65 women, median age 42.6 years) were randomized. Eighty-four patients completed the study (45 low FODMAP, 39 mNICE). Baseline demographics, symptom severity, and nutrient intake were similar between groups. Fifty-two percent of the low FODMAP vs. 41% of the mNICE group reported adequate relief of their IBS-D symptoms (P=0.31). Though there was no significant difference in the proportion of composite end point responders (P=0.13), the low FODMAP diet resulted in a higher proportion of abdominal pain responders compared with the mNICE group (51% vs. 23%, P=0.008). Compared with baseline scores, the low FODMAP diet led to greater reductions in average daily scores of abdominal pain, bloating, consistency, frequency, and urgency than the mNICE diet.
CONCLUSIONS
In this US trial, 40-50% of patients reported adequate relief of their IBS-D symptoms with the low FODMAP diet or a diet based on modified NICE guidelines. The low FODMAP diet led to significantly greater improvement in individual IBS symptoms, particularly pain and bloating, compared with the mNICE diet.
Low FODMaP diet reduces pain and bloating for IBS-D
This study compared two dietary recommendations for diarrhea-dominant IBS. One (FODMaP) reduces sugars that are poorly absorbed, causing an osmotic shift of fluid into the gut. These sugars are also highly fermentable by bacteria in the gut, causing gas and bloating. The other diet (NICE Guidelines) is based on prior nutritional findings for IBS, suggesting improvement if the patient avoids trigger foods, eats small frequent meals, and avoids excess alcohol and caffeine.
The study did not provide the food to the participants, only specific dietary recommendations by a trained nutritionist. A dietary diary was then kept. This study did not have a no-treatment arm, which would have been nice since simply having a caring nutritionist give you guidance on how to eat to improve your symptoms has significant nonspecific healing effects. And that is exactly what this study showed. Both groups had 40% to 50% improvement in overall symptoms; however, the FODMaP group had significantly greater benefits in terms of reduced pain and bloating.
How to prescribe a FODMaP diet?
To be simple, reduce the sugar load. Anyone who brews beer knows that, when you combine a sugar (malt) and an organism (yeast), you encourage fermentation, which creates a lot of gas. The same concept is true with FODMaP. When we eat a lot of sugar, it combines with our microbiota to cause gas and bloating.
FODMaP is an acronym for the following:
Fermentable
Oligosaccharides—Fructans found in wheat, rye, onion, garlic, beans, and some vegetables
Disaccharides—Lactose in milk and dairy
Monosaccharides—Fructose in high-fructose corn syrup, honey, and some fruits
and
Polyol sweeteners—These end in “ol” such as xylitol, sorbitol, etc. Sugarless gum often has xylitol in it that can cause gas and bloating.
I find it most useful to recommend the app created by Monash University (one of the pioneers in the FODMaP research) to my patients, which provides more specific guidance and can be found here.
The clinician needs to remember that this diet is not easy to maintain and is not intended to be used long term. The idea is that the total sugar content is reduced to help patients find relief and then they are encouraged to slowly re-introduce some of these healthier foods (vegetables, beans, and fruit) back into the diet while maintaining a low total sugar burden.
You may want to read “MY APPROACH to Nutritional Therapy for Irritable Bowel Syndrome,” posted onPracticeUpdate in spring of 2015.