Starch- and sucrose-reduced diet tops low FODMAP for IBS symptoms in network meta-analysis

A starch- and sucrose-reduced diet outperformed a low FODMAP diet for improving global irritable bowel syndrome symptoms, according to a 2025 network meta-analysis published in The Lancet Gastroenterology & Hepatology. The analysis pooled 28 randomised controlled trials covering 2,338 patients across 11 dietary interventions. It is the most comprehensive head-to-head comparison of IBS diets yet conducted.

The starch- and sucrose-reduced diet, tested in two trials with a combined 217 patients, produced a 59 percent reduction in the risk of global IBS symptoms not improving compared with a habitual diet (RR 0.41; 95% CI 0.26 to 0.67). Its P-score of 0.84 gave it an 84 percent probability of being the most effective intervention when all diets were compared against each other.

The low FODMAP diet, by far the most studied intervention with 24 trials and 1,803 patients, reduced symptom risk by 49 percent (RR 0.51; 95% CI 0.37 to 0.70, P-score 0.71). It ranked fourth for global symptoms. The low FODMAP approach restricts fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, which are present in wheat, certain fruits and vegetables, legumes, and artificial sweeteners. These compounds either increase small-intestinal water content through osmotic effects or undergo microbial fermentation in the colon; both can trigger symptoms in people with IBS.

The BDA/NICE diet, which forms the basis of standard dietary advice for IBS in the UK, ranked tenth with a 38 percent risk reduction (RR 0.62; 95% CI 0.43 to 0.90, P-score 0.44) across eight trials and 710 patients. This diet includes recommendations to eat small regular meals, limit caffeine and alcohol, and reduce fatty foods.

Lead authors Melanie Cuffe of Leeds Gastroenterology Institute and Heidi Staudacher of Monash University, with joint last authors Christopher Black and Alexander Ford, conducted the analysis with collaborators at seven institutions across four continents. The study received no external funding. All authors declared no conflicts of interest.

What the analysis found for each symptom

The paper examined four symptom categories: global symptoms, abdominal pain, bloating or distension, and bowel habit. The starch- and sucrose-reduced diet performed well for global symptoms and abdominal pain (ranked second, RR 0.54; 95% CI 0.33 to 0.90). But its evidence base is thin. Only two trials exist, both from the same research group in Sweden, totalling 217 patients between them.

The low FODMAP diet was the only intervention superior to habitual diet for abdominal bloating or distension (RR 0.55; 95% CI 0.37 to 0.80), assessed across 23 trials and 1,773 patients. For bowel habit, no dietary intervention beat any control in a statistically meaningful way, though the low FODMAP diet outperformed the BDA/NICE diet on this endpoint (RR 0.79; 95% CI 0.63 to 0.99) across 21 trials including 1,666 patients.

Several diets posted striking rankings but rest on minimal evidence. A gluten-free diet ranked second for global symptoms (RR 0.45; 95% CI 0.25 to 0.81, P-score 0.78), from a single trial of 114 patients. A tritordeum-based diet, which uses a wheat variety with reduced immunogenic gluten peptides, ranked third (RR 0.48; 95% CI 0.26 to 0.89), also from only one trial. The FODMAP-simple diet, which restricts only the most commonly implicated FODMAPs rather than the full spectrum, ranked seventh (RR 0.56; 95% CI 0.33 to 0.96) in a single trial of 35 patients. A low-carbohydrate diet ranked eighth (RR 0.57; 95% CI 0.35 to 0.94) in one trial of 202 patients. These results are hypothesis-generating. They are not ready to guide clinical practice.

When the analysis was restricted to 12 trials that enrolled only patients with IBS with diarrhoea (IBS-D) or excluded those with constipation, the low FODMAP diet moved up to third for global symptoms (RR 0.41; 95% CI 0.20 to 0.82, P-score 0.78), assessed in all 12 trials across 879 patients. The diet may be especially effective for diarrhoea-predominant IBS. The authors caution against reading too much into subgroup analyses.

How much confidence to place in these rankings

The researchers used the CINeMA framework (Confidence in Network Meta-Analysis), endorsed by the Cochrane Collaboration, to rate the certainty of every comparison in the network. The result was stark: all direct and indirect comparisons were rated low or very low confidence, with two exceptions. The direct comparison between a low FODMAP diet and habitual diet, and between a starch- and sucrose-reduced diet and habitual diet, both reached moderate confidence.

“The most evidence exists for a low FODMAP diet,” the authors write, “but other promising therapies are emerging and should be the subject of further study.” They note that the FODMAP-simple diet, gluten-free diet, and starch- and sucrose-reduced diet “may be considerably easier to implement than a low FODMAP diet” but “are also predominantly restrictive in nature and should be the subject of definitive trials before recommendations are made for clinical practice.”

The evidence for low FODMAP is broad but not deep in the confidence ratings. Only two trials compared any active diet against a placebo (sham) diet. Blinding is a structural problem: no trial was at low risk of bias across all domains, and only three trials explicitly stated they were double-blind. In dietary trials, where participants know what they are eating, perfect blinding may be unachievable. The authors argue that a sham diet or BDA/NICE comparator could at least enable designs where participants are uncertain which arm they are in.

Adverse events were reported in only eight of the 28 trials, and in insufficient detail to allow pooling. Eleven trials formally assessed dietary adherence, with no differences between arms in nine. The authors flag this as a gap: “future trials in this field should assess dietary adherence and potential dietary confounding, report complete adverse events data, and evaluate acceptability to patients.”

What this means for patients

Up to 80 percent of people with IBS report food-related symptoms, and patients consistently prefer dietary treatments over pharmacological ones. A 2013 survey by Bohn and colleagues documented this preference; a 2022 discrete-choice experiment by Sturkenboom and colleagues reinforced it. This meta-analysis confirms that diet works. But the choice of which diet may matter less than the fact of structured dietary intervention itself.

Nineteen of the 22 trials in which the diet was delivered by counselling used a dietitian or nutritionist. The authors are explicit that “supervision is likely to be implicated in its efficacy” for low FODMAP, and that dietitian-delivered care has implications for access. Smartphone apps might offer a scalable alternative for delivering the low FODMAP diet. They cannot, however, screen for the nutritional red flags that a trained clinician catches during restrictive diet supervision, nor monitor nutritional adequacy.

Long-term restriction is not recommended. Only two of the 28 trials incorporated a structured reintroduction phase. The longer-term safety and sustainability of these diets, particularly their effects on the gut microbiome and nutritional adequacy, remain unknown. No RCTs of dietary interventions for IBS have been conducted in primary care, which is where most IBS is managed and where current NICE guidance places dietary advice.

The bottom line

For clinicians, the practical takeaway: start with a low FODMAP diet under dietetic supervision because it has the largest and most consistent evidence base across symptom domains. The starch- and sucrose-reduced diet is a promising alternative that may be simpler for patients to follow, but it needs replication in larger trials at multiple centres before it can be recommended first-line. The BDA/NICE diet remains a reasonable, less restrictive starting point for patients who find FODMAP elimination too burdensome.

For patients, the evidence is encouraging: dietary interventions work for IBS, and the evidence base has more than doubled since the same group’s 2022 meta-analysis in Gut. The key variable may not be which specific diet you follow, but whether you follow it with professional guidance. Several diets that are simpler to implement than low FODMAP are emerging. The next wave of definitive trials may broaden the menu considerably.

References

1. Cuffe MS, Staudacher HM, Aziz I, et al. Efficacy of dietary interventions in irritable bowel syndrome: a systematic review and network meta-analysis. The Lancet Gastroenterology & Hepatology 10(6):520-536. 2025. https://doi.org/10.1016/s2468-1253(25)00054-8
2. Black CJ, Staudacher HM, Ford AC. Efficacy of a low FODMAP diet in irritable bowel syndrome: systematic review and network meta-analysis. Gut 71:1117-1126. 2022. https://doi.org/10.1136/gutjnl-2021-325214
3. Bohn L, Storsrud S, Tornblom H, et al. Self-reported food-related gastrointestinal symptoms in IBS are common and associated with more severe symptoms and reduced quality of life. Am J Gastroenterol 108:634-641. 2013. https://doi.org/10.1038/ajg.2013.105