A diet low in fermentable carbohydrates can reduce gut symptoms related to inflammatory bowel disease (IBD), according to a study by U.K. researchers.
Fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) occur in a number of common foods, including certain fruits, vegetables, and dairy products. They can draw increased water to the gut, and through microbial fermentation increase hydrogen in the colon.
While previous research has shown that a low-FODMAP diet can relieve gut symptoms such as swelling and flatulence in people with irritable bowel syndrome, the diet has been little studied in IBD patients, for whom gut symptoms often persist even in the absence of gastrointestinal inflammation. In a study published in Gastroenterology, Selina Cox, MD, of King’s College, London, and colleagues randomized 52 people with ulcerative colitis or Crohn’s disease with persistent gut symptoms but without active inflammation to 4 weeks on a low-FODMAP diet (n = 27) or a control diet comprising sham dietary advice (n = 25). Investigators were not blinded to treatment allocation.
At 4 weeks, Dr. Cox and her colleagues reported more patients on the low-FODMAP diet reported “adequate” relief of gut symptoms (52% vs. 16%, P = .007), and saw slight improvements in health-related quality of life scores, compared with the control group. Patient-reported flatulence and bloating were significantly lower in the treatment group, while few other symptom-specific differences were seen between groups.
Stool samples collected at baseline and at the study’s endpoint showed significantly reduced abundance of three types of gut bacteria thought to have a role in immune response – Bifidobacterium adolescentis, B longum, and Faecalibacterium prausnitzii – compared with control subjects. But there were no significant between-group differences in bacterial diversity or in biomarkers of inflammation.
“A major strength of this trial is that low-FODMAP dietary advice was compared to sham dietary advice, providing the first placebo-controlled evidence of effectiveness in IBD,” the researchers wrote in their analysis. Weaknesses of the study include its single-blinded design and inability to control for nutritional alterations related to the low-FODMAP diet.
Ms. Cox and her colleagues recommended a 4-week low-FODMAP diet along with “expert advice and intensive follow-up” for the management of gut symptoms in IBD, but cautioned that longer-term use may not be appropriate.
The study was funded by the U.S.-based Kenneth Rainin Foundation. Two of Dr. Cox’s coauthors declared financial conflicts of interest from a patent on a mobile application to support the low-FODMAP diet; the study’s corresponding author, Kevin Whelan, PhD, additionally reported receiving fees or research support from food and nutrition firms.
SOURCE: Cox S et al. Gastroenterology 2019. doi: 10.1053/j.gastro.2019.09.024.