Published online Sep 6, 2021. doi: 10.12998/wjcc.v9.i25.7417
Peer-review started: April 29, 2021
First decision: May 26, 2021
Revised: June 15, 2021
Accepted: July 16, 2021
Article in press: July 16, 2021
Published online: September 6, 2021
Irritable bowel syndrome (IBS) has a complicated pathogeny involving many factors. IBS patients apply to clinics again and again and undergo numerous examinations and procedures that may not be necessary at all. Among the tools for treating IBS, various diets, antispasmodics, loperamide, antidepressants, psychological therapies (psychotherapy, hypnosis, etc.), laxatives, biofeedback, prebiotics or probiotics can be used. Even though some or all of these treatments relieve the symptoms in some patients, some of the patients do not recover sufficiently and may need other treatment alternatives. Because the presence of a relationship between IBS and diet has been shown by various studies, some diet modifications are recommended to reduce symptoms. The elimination diet is a widely used treatment of IBS. Recently, a gradually increasing number of studies have shown a 50%-80% significant effect of a 4-8 wk low fermentable oligo, di- and mono-saccharides and polyols (FODMAP) diet on the symptoms of IBS patients. The efficacy of a low FODMAP diet may depend on factors such as the demographic characteristics, microbiota composition and metabolism besides the IBS subtype and particularly dietary adherence of the patients. There is evidence to suggest the vital role of microbiota in pathophysiology of IBS. The balance of the intestinal flora is corrected by probiotics by way of limiting the pathogenic bacteria colonization. Reasoning on this argument, probiotics have been used in treatment of IBS for a long time.
A low FODMAP diet and probiotics are used individually in IBS treatment. Today, they are preferable treatments due to their relatively high efficacy and few side effects. Combination of these two may improve symptom control in patients. However, the negative effects of a low FODMAP diet on intestinal flora and its long-term adverse effects are still inconclusive. Also, even though the dietary adherence rate is high, a group of patients still cannot tolerate it. Having the potential of preventing possible harmful effects of low FODMAP diet on the intestinal flora, adding probiotics into it may affect control of IBS symptoms.
This randomized double-blind prospective controlled study aimed to find out how probiotic supplementation to a low FODMAP diet affects symptoms in all subtypes of IBS.
This double-blind randomized prospective study included 100 patients aged 18-65 newly and/or previously diagnosed with IBS as per the Rome IV criteria whose IBS treatment was not changed during the last 4 wk. According to their IBS subtypes, the patients were divided into subgroups categorized as IBS-diarrhea dominant type, IBS-constipation dominant type and IBS-mixed type. Patients were randomly assigned to two groups: 21 d low FODMAP diet + probiotic (Group 1) and 21 d low FODMAP diet + placebo (Group 2). A coin was tossed to categorize the patients into two groups randomly and neither the patient nor the researcher knew about the treatment administered to the patient. Each patient had a face-to-face explanatory conversation lasting at least 45 min with an expert dietitian about the diet to be followed throughout the trial. The provider of the probiotic and placebo drugs was Nobel Ilac San. ve Tic. A.S. Istanbul, Turkey®. Supplementary food containing probiotics (2 g) was prescribed to patients once a day as a probiotic. This product contained Streptococcus thermophilus (5.4 × 108 cfu), Bifidobacterium lactis (5.4 × 108 cfu), Lactobacillus acidophilus (4.5 × 108 cfu), Lactobacillus plantarum (4 × 108 cfu) and Bifidobacterium breve (4 × 108 cfu). Placebos were identical-looking capsules without any probiotics. All the participants were asked to record all the foods and beverages they consumed in a diary. Moreover, by weekly phone calls their dietary adherence in terms of probiotic/placebo compliance was monitored. Before and after applying a 21 d low FODMAP diet + placebo or a low FODMAP diet + probiotic, the symptoms of the patients were evaluated with the reference scale and scoring systems, and the results obtained were analyzed. We used the following scales to evaluate the patients: visual analogue scale (VAS) to evaluate pain before and after a 21 d low FODMAP diet + probiotic/placebo, Bristol Stool Scale to identify IBS type and any changes observed in stool and IBS-Symptom Severity Scale (IBS-SSS) to evaluate the severity of IBS symptoms. In the evaluation made after 21 d treatment, the following outcomes were acknowledged as clinical improvement: a decrease of at least 50 points in the IBS-SSS score, a decrease of more than 10 mm in pain severity according to VAS and change in stool characterization to Type 3 and Type 4 according to the Bristol Stool Chart.
A total of 85 patients, 43 from Group 1 and 42 from Group 2, completed the study to the end. IBS subtype breakdown showed that the most common subgroup was the constipation-predominant IBS, which was followed by diarrhea-predominant IBS. In both groups, the VAS score, IBS-SSS total score and IBS-SSS sub-parameters measured before treatment were similar. There was a significant decrease in the VAS score, IBS-SSS total score and IBS-SSS sub-parameter scores of Groups 1 and 2 after treatment (P < 0.001). The IBS-SSS score of 37 (86.04%) patients in Group 1 and 36 (85.71%) patients in Group 2 decreased by more than 50 points. In conclusion, in both groups abdominal pain and symptoms within the scope of IBS-SSS decreased significantly after treatment. Moreover, no side effects were observed in any of the patients that were included in this study. Treatment outcomes showed that the scores of 38 (79.2%) out of 48 patients who had severe IBS improved after treatment. Significant changes in stool shape were found in both groups when they were analyzed with Kappa index according to the Bristol Stool Scale after treatment. The average adherence rate of the 85 patients who completed the study to the FODMAP restricted diet was 92%, being 90% in Group 1 and 94% in Group 2. There was no significant difference between these two groups (P = 0.066).
According to our findings, a low FODMAP diet significantly relieved IBS symptoms in all IBS subtypes at the initial phase; however, adding probiotics to the diet made no additional contributions to symptom relief.
The limitation of our study was that we did not analyze stool microbiota of the patient group that received probiotics or placebo in addition to the FODMAP restricted diet before and after treatment. Further and longer term research using different probiotics is needed to assess the efficacy of probiotic supplementation to a low FODMAP diet in IBS.