Efficacy of a low FODMAP diet in irritable bowel syndrome: systematic review and network meta-analysis

Abstract

ObjectiveA diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) is recommended for irritable bowel syndrome (IBS), if general lifestyle and dietary advice fails. However, although the impact of a low FODMAP diet on individual IBS symptoms has been examined in some randomised controlled trials (RCTs), there has been no recent systematic assessment, and individual trials have studied numerous alternative or control interventions, meaning the best comparator is unclear. We performed a network meta-analysis addressing these uncertainties.DesignWe searched the medical literature through to 2 April 2021 to identify RCTs of a low FODMAP diet in IBS. Efficacy was judged using dichotomous assessment of improvement in global IBS symptoms or improvement in individual IBS symptoms, including abdominal pain, abdominal bloating or distension, and bowel habit. Data were pooled using a random effects model, with efficacy reported as pooled relative risks (RRs) with 95% CIs, and interventions ranked according to their P-score.ResultsWe identified 13 eligible RCTs (944 patients). Based on failure to achieve an improvement in global IBS symptoms, a low FODMAP diet ranked first vs habitual diet (RR of symptoms not improving=0.67; 95% CI 0.48 to 0.91, P-score=0.99), and was superior to all other interventions. Low FODMAP diet ranked first for abdominal pain severity, abdominal bloating or distension severity and bowel habit, although for the latter it was not superior to any other intervention. A low FODMAP diet was superior to British Dietetic Association (BDA)/National Institute for Health and Care Excellence (NICE) dietary advice for abdominal bloating or distension (RR=0.72; 95% CI 0.55 to 0.94). BDA/NICE dietary advice was not superior to any other intervention in any analysis.ConclusionIn a network analysis, low FODMAP diet ranked first for all endpoints studied. However, most trials were based in secondary or tertiary care and did not study effects of FODMAP reintroduction and personalisation on symptoms.

Evaluating tolerability of resistant starch 2, alone and in combination with minimally fermented fibre for patients with irritable bowel syndrome: a pilot randomised controlled cross-over trial

“…Rapidly fermented fibres (fructans and galactooligosaccharides) appear to be less suitable for patients with IBS, with meta-analyses revealing their supplementation did not ameliorate symptoms and, in some cases, led to symptom exacerbation ( 10 ) . Indeed, dietary restriction of these fibres (alongside other short-chain carbohydrates) in the low FODMAP diet has been utilised as an effective diet therapy in IBS ( 11 ) . Similarly, fibre complexes containing rapidly fermented fractions, namely wheat bran, also appear to be less suitable for patients with IBS ( 3 ) .…”

Long‐term personalized low FODMAP diet in IBS

“…To account for strong placebo effect described in IBS patients, 19,20 multiple randomized controlled trials (RCTs) were performed to investigate the efficacy of the low FODMAP diet in comparison with the typical diet, the habitual diet, the high FODMAP diet, or the traditional/sham/alternative dietary advice. Most of these studies showed beneficial effects of the low FODMAP diet in IBS symptoms, 6,8,21‐25 and few studies observed similar treatment efficacy compared to a traditional dietary advice, 6,26 a general dietary advice, 27 yoga, 28 or hypnotherapy 29 . Furthermore, concerns were raised due to the restrictive nature of this diet, as nutritional adequacy might be at risk 30 .…”

“…IBS patients often modify their diet, as over 80% of patients report food‐related symptoms 3 . Specific dietary triggers, such as gluten or poorly fermentable carbohydrates, have been frequently reported to worsen symptoms in IBS patients 4‐6 . Thus, dietary interventions are often proposed by clinicians or self‐administered by patients as initial therapeutic approaches to curb IBS symptoms.…”

“…A diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) is now considered by many a first‐line treatment option for IBS 7 . Despite growing number of randomized clinical trials assessing the efficacy of a low FODMAPs diet in reducing IBS symptoms, the quality of the evidence has been questioned, due to the likely presence of bias in dietary intervention trials 6 . However, a recent systematic review and network analysis demonstrated the superiority of the low FODMAP diet over alternative interventions, including British Dietetic Association (BDA)/National Institute for Health and Care Excellence (NICE) dietary advice 7 …”

Gut‐brain axis dysfunction underlies FODMAP‐induced symptom generation in irritable bowel syndrome

“…Diet is increasingly considered as treatment, 2 specifically a diet low in fermentable oligo-, di-and monosaccharides and polyols (FODMAPs) has shown to be an effective strategy to reduce IBS symptoms. 3 FODMAPs are poorly absorbed short-chain carbohydrates including fructose (in excess of glucose), lactose, polyols, fructans and galacto-oligosaccharides. They are found in a wide variety of foods, and may trigger lower gastrointestinal (GI) symptoms by inducing luminal distention through their osmotic effects in the small intestine and via bacterial fermentation in the colon, resulting in increased gas production.…”