A diet with reduced content of fermentable short chain carbohydrates (fermentable oligo-, di-, monosaccharides and polyols, FODMAPs) has been reported to be effective in the treatment of patients with irritable bowel syndrome (IBS). However, there is no evidence for its superiority to traditional dietary advice for these patients. We compared the effects a diet low in FODMAPs with traditional dietary advice in a randomized, controlled trial of patients with IBS.