There was strong proof that a diet low in fermentable oligo-, di-, monosaccharides, and polyols (FODMAPs) helps individuals with Irritable Bowel Syndrome and diarrhea (IBS-D) feel better. Although individuals with IBS with constipation (IBS-C) or mixed bowel habits (IBS-M) are using the low-FODMAP diet more frequently, there was no evidence to back it up. Researchers sought to compare the practical efficacy of a low-FODMAP diet in patients with IBS-D, IBS-C, and IBS-M.

Patients with suspected IBS met with a registered dietitian and filled out the IBS symptom severity scale (IBS-SSS) survey before beginning the low-FODMAP diet and after the restriction phase of the diet plan. The study used a commercially available meal procurement service that prepared and delivered meals certified low in FODMAP content (Modify Health, Atlanta, GA). A responder was classified as someone who had an IBS-SSS score drop of >100.

IBS-SSS questionnaires were completed at baseline and after elimination by 403 IBS patients. A GI expert referred 26% of patients; the remaining 74% were self-referrals. Prior to the intervention, 193 (48%) of the patients had severe IBS (IBS-SSS > 300). Patients with IBS-D saw reductions in discomfort by 71%, bloating by 56%, and satisfaction with bowel movements by 55%. Improvement in the overall IBS-SSS >100 was seen in 77% of IBS-D patients. Patients with IBS-C saw reductions in discomfort by 69%, bloating by 49%, and satisfaction with bowel movements by 42%. IBS-SSS scores improved in 67% of IBS-C patients. Patients with IBS-M reported 85% reductions in discomfort, 55% reductions in bloating, and 53% reductions in dissatisfaction with bowel movements. IBS-SSS scores overall improved in 72% of IBS-M patients. IBS-SSS improvements of 174 and 40% for those who had commercial meals “all” during the restriction phase were significantly greater than the improvements of 153 and 33% for consumed them “some” of the time during the elimination phase (P=0.059 and 0.03, respectively).

According to the research, all IBS subtypes, including IBS-C and IBS-M, can benefit from a low-FODMAP diet. Compared to patients who only received meals for a portion of the restriction phase, those who received prepared low-FODMAP meals for the full restriction phase benefited more.