Low FODMAP diet.

Evidence Four RCTs with mainly young female participants compared the LFD to a normal diet (ND). • Denmark: the largest, high-quality, 6-week, open-label RCT of 123 IBS patients receiving specialist care.1 -On a 500-point symptom scale (minimal clinically important difference was 50),2 LFD led to an improvement of about 150, probiotics about 80, and ND about 30 points. -Subgroup analysis: only diarrhea patients improved. -Limitations: pre-enrolment investigations included colonoscopy and genetic lactase deficiency testing; analysis was per protocol. • Australia: blinded crossover trial of LFD versus ND (each for 3 weeks, with a 3-week washout period) of 30 IBS patients and 8 controls in primary or secondary care.3 -Global gastrointestinal symptoms: with LFD 70% had a more than 10-point improvement on a 100-point scale. -Limitations: ND results not reported; high-fibre diet included in LFD arm; authors had conflicts of interest. • United Kingdom: 3-week, non-blinded RCT of 41 patients with diarrhea-predominant IBS or substantial bloating, receiving specialist care.4 -Adequate symptom control was reported for 68% of LFD and 23% of ND patients (NNT = 3); however, symptom control at baseline was different (not significantly): 37% for LFD and 58% for ND; symptoms actually worsened in the ND arm (58% controlled at baseline, 23% at the end). • Fourth RCT: too short (2 days) to draw conclusions.5 • Two systematic reviews had conflicting conclusions6,7: -More research is required6 or LFD is efficacious in treating functional gastrointestinal symptoms.7