AIM: To investigate the effects of a low fermentable, oligosaccharides, disaccharides, monosaccharides and polyols diet (LFD) and the probiotic Lactobacillus rhamnosus GG (LGG) in irritable bowel syndrome (IBS).

METHODS: Randomised, unblinded controlled trial on the effect of 6-wk treatment with LFD, LGG or a normal Danish/Western diet (ND) in patients with IBS fulfilling Rome III diagnostic criteria, recruited between November 2009 and April 2013. Patients were required to complete on a weekly basis the IBS severity score system (IBS-SSS) and IBS quality of life (IBS-QOL) questionnaires in a specially developed IBS web self-monitoring application. We investigated whether LFD or LGG could reduce IBS-SSS and improve QOL in IBS patients.

RESULTS: One hundred twenty-three patients (median age 37 years, range: 18-74 years), 90 (73%) females were randomised: 42 to LFD, 41 to LGG and 40 to ND. A significant reduction in mean ± SD of IBS-SSS from baseline to week 6 between LFD vs LGG vs ND was revealed: 133 ± 122 vs 68 ± 107, 133 ± 122 vs 34 ± 95, P < 0.01. Adjusted changes of IBS-SSS for baseline covariates showed statistically significant reduction of IBS-SSS in LFD group compared to ND (IBS-SSS score 75; 95%CI: 24-126, P < 0.01), but not in LGG compared to ND (IBS-SSS score 32; 95%CI: 18-80, P = 0.20). IBS-QOL was not altered significantly in any of the three groups: mean ± SD in LFD 8 ± 18 vs LGG 7 ± 17, LFD 8 ± 18 vs ND 0.1 ± 15, P = 0.13.

CONCLUSION: Both LFD and LGG are efficatious in patients with IBS.