Clinical effectiveness of adding probiotics to a low FODMAP diet: Randomized double-blind placebo-controlled study

There are various studies showing the relationship between irritable bowel syndrome (IBS) and diet, and some dietary adjustments are recommended to reduce symptoms. In recent years, there is a growing number of studies that show a 4-8 wk low fermentable oligo, di- and mono-saccharides and polyols (FODMAP) diet has a 50%-80% significant effect on symptoms in IBS patients. There is strong evidence suggesting that changes in fecal microbiota have an impact on IBS pathogenesis. Based on this argument, probiotics have been used in IBS treatment for a long time. As is seen, the FODMAP diet and probiotics are used separately in IBS treatment.

To evaluate the effectiveness of adding probiotics to a low FODMAP diet to control the symptoms in patients with IBS.

The patients who were admitted to the Gastroenterology Clinic of Dokuz Eylul University Hospital and diagnosed with IBS according to Rome IV criteria were enrolled into the study. They were randomized into 2 groups each of which consisted of 50 patients. All patients were referred to a dietitian to receive dietary recommendations for the low FODMAP diet with a daily intake of 9 g. The patients were asked to keep a diary of foods and beverages they consumed. The patients in Group 1 were given supplementary food containing probiotics (2 g) once a day in addition to their low FODMAP diet, while the patients in Group 2 were given a placebo once a day in addition to their low FODMAP diet. Visual analogue scale (VAS), the Bristol Stool Scale and IBS Symptom Severity Scale (IBS-SSS) scores were evaluated before and after the 21 d treatment.

The rate of adherence of 85 patients, who completed the study, to the FODMAP restricted diet was 92%, being 90% in Group 1 and 94% in Group 2. The mean scores of VAS and IBS-SSS of the patients in Group 1 before treatment were 4.6 ± 2.7 and 310.0 ± 78.4, respectively, and these scores decreased to 2.0 ± 1.9 and 172.0 ± 93.0 after treatment (both P < 0.001). The mean VAS and IBS-SSS scores of the patients in Group 2 before treatment were 4.7 ± 2.7 and 317.0 ± 87.5, respectively, and these scores decreased to 1.8 ± 2.0 and 175.0 ± 97.7 after treatment (both P < 0.001). The IBS-SSS score of 37 patients (86.04%) in Group 1 and 36 patients (85.71%) in Group 2 decreased by more than 50 points. Group 1 and Group 2 were similar in terms of differences in VAS and IBS-SSS scores before and after treatment. When changes in stool shape after treatment were compared using the Bristol Stool Scale, both groups showed significant change.

This study is the randomized controlled study to examine the efficiency of probiotic supplementation to a low FODMAP diet in all subtypes of IBS. The low FODMAP diet has highly positive effects on symptoms of all subtypes of IBS. It was seen that adding probiotics to a low FODMAP diet does not make an additional contribution to symptom response and adherence to the diet.