The low FODMAP (Fermentable Oligo-, Di- and Monosaccharides and Polyoles) diet (LFD) allegedly reduces symptoms of irritable bowel syndrome (IBS). Eleven studies have examined the effects of LFD on IBS. Most studies reported a symptomatic effect, but methodological weaknesses such as lack of relevant control group and of proper blinding means that a placebo response cannot be excluded. No studies have examined the effect of the important reintroduction phase nor the effects of LFD on IBS patients in primary care. Evidence suggests that intake of high dose FODMAP can induce gastrointestinal symptoms, but the clinical relevance of this is doubtful.