MVIIIHealth The MVIII app
← Back

Research · Diets

Low-FODMAP diet

Meta-analyses of IBS trials find a low-FODMAP diet improves global symptoms and bloating more than habitual diet or standard dietary advice, from trials of very low to moderate quality. Gut Bifidobacteria fell consistently, with no clear change in microbiome diversity. Intake of most nutrients held over 4 to 12 weeks, while diet quality scores fell.

Add to Bio HackChecked 2026-11-13
Status
A dietary pattern, not a regulated product.
Also called
low FODMAP diet, FODMAP diet, low-FODMAP, LFD, Monash diet, FODMAP elimination diet, fermentable carbohydrate restriction
Followed for
IBS, bloating, abdominal pain, gas, gut symptoms, gut symptoms in inflammatory bowel disease

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help4

Reported risks3

What people follow it for, and what was found

Shown to help4

Strong

IBS symptoms

Shown to improve global IBS symptoms more than habitual diet or standard advice, with about a third lower risk of symptoms not improving.

Compared with habitual diet and British Dietetic Association and NICE dietary advice, among the comparisons in a network meta-analysis [1]; a traditional IBS diet following NICE and British Dietetic Association advice, the participants' habitual diet, a typical diet for the study's country (Australian; Danish or Western), a high-FODMAP diet, a balanced Mediterranean diet or a sham exclusion diet [2]; various control interventions, an alternative or usual diet [3]; a sham diet that restricted a similar number of foods [4]

The numbers and sources
Effect
In 13 RCTs (944 patients), the relative risk of global symptoms not improving was 0.67 against habitual diet (95% CI 0.48 to 0.91), and the diet ranked first for abdominal pain, bloating and bowel habit. It beat British Dietetic Association and NICE dietary advice for bloating (RR 0.72, 95% CI 0.55 to 0.94) [1]. In 12 trials, IBS severity fell against control diets (SMD -0.66, 95% CI -0.88 to -0.44), by 45 points on the IBS-SSS, and IBS quality of life rose 4.93 points [2]. In 7 RCTs (397 participants), the relative risk of symptoms remaining was 0.69 (95% CI 0.54 to 0.88) [3]. In a sham-diet controlled trial, 57% on the diet and 38% on sham reported adequate relief by intention to treat (P = 0.051), and IBS-SSS was 173 against 224 (P = 0.001) [4].
Population
Adults with IBS, mostly in secondary or tertiary care [1][2][3]; 104 adults with IBS at 2 UK hospitals [4].
Sources
[1], [2], [3], [4]
Caveats
GRADE quality was very low in [3], and trials with rigorous control diets showed the least heterogeneity and the smallest effects. Most trials did not study reintroduction and personalization [1].
Moderate

IBS symptoms over 6 months or more

Shown to lower gut symptoms and anxiety and raise quality of life in IBS over at least 6 months, in a meta-analysis of five studies.

Compared with comparisons the source does not describe, whether control diets or the same people before the diet [5]

The numbers and sources
Effect
Over at least 6 months, overall gastrointestinal symptoms fell (SMD -1.97, 95% CI -3.63 to -0.30), as did anxiety (SMD -0.40) and depression (SMD -0.28), and quality of life rose (MD 0.53). Sleep quality did not change [5].
Population
324 patients with IBS in 5 studies [5].
Sources
[5]
Caveats
Five studies, with a wide confidence interval for symptoms. The abstract does not say how many studies had a control group [5].
Moderate

Gut symptoms in inflammatory bowel disease

Shown to ease functional gut symptoms in inflammatory bowel disease, without changing stool consistency or markers of gut inflammation.

Compared with a normal habitual diet or a sham diet, in 4 RCTs; before the diet, in the same people, in 5 before-after studies [6]

The numbers and sources
Effect
Functional gut symptoms improved (RR 0.47, 95% CI 0.33 to 0.66) and disease-specific quality of life rose (MD 11.24). Stool consistency, the Mayo score for ulcerative colitis and fecal calprotectin did not differ [6].
Population
446 people with inflammatory bowel disease and functional gut symptoms in 4 RCTs and 5 before-after studies [6].
Sources
[6]
Caveats
More than half the studies had no control group [6].
LimitedStudied in children

Children with IBS or functional abdominal pain

Limited evidence: abdominal pain eased in children with IBS on the diet, in mostly uncontrolled studies, with less certain benefit for functional abdominal pain.

Compared with before the diet, in the same children, pooled single-arm from randomized and observational studies [7]

The numbers and sources
Effect
Across 10 studies (612 children), abdominal pain intensity fell (SMD -1.37, 95% CI -2.18 to -0.57). Pain frequency improved in IBS but not in functional abdominal pain, and stool frequency did not change. Satisfaction was 83% in IBS and 43% in functional abdominal pain [7].
Population
Children and adolescents with IBS or functional abdominal pain [7].
Sources
[7]
Caveats
Single-arm meta-analyses with substantial heterogeneity and frequent risk of bias, especially in observational studies [7].

How trials defined it

FODMAPs are fermentable oligosaccharides, disaccharides, monosaccharides and polyols [1]. Two trials ran the diet for 4 weeks, one with dietary counseling for every group [4][8]. Its sham diet restricted a similar number of staple and other foods and was as hard to follow [4]. One open-label study kept a strict version for 12 weeks [9]. The long-term review counted 6 months or more on the diet [5]. Most trials did not test the reintroduction and personalization steps [1].

Risks

Reported risks2

Strong

Lower Bifidobacteria in the gut

Shown to lower gut Bifidobacteria in IBS, with no consistent change in microbiome diversity, fecal short-chain fatty acids or fecal pH.

The numbers and sources
Effect
Across 9 trials (403 patients), the diet consistently lowered Bifidobacteria, with no clear effect on diversity or other taxa, and no difference in total fecal short-chain fatty acids (SMD -0.25, 95% CI -0.63 to 0.13) or fecal pH [10]. After 4 weeks, concentrations and proportions of bifidobacteria were lower than on habitual diet (P < 0.001), while total bacteria did not differ [8]. Against a sham diet, Bifidobacterium abundance was 8.8 against 9.2 rRNA genes per g (P = 0.008), and a multistrain probiotic raised it [4].
Population
Adults with IBS in randomized trials [4][8][10].
Sources
[4], [8], [10]
Caveats
What the lower Bifidobacteria means for health has not been determined [8].
Limited

Disordered eating

Linked to disordered eating behaviors in 38% of people with IBS years after FODMAP education, tied to distress and symptoms, not to the diet followed.

The numbers and sources
Effect
A mean of 7.1 years after FODMAP education, 38% screened positive for disordered eating on at least one tool: 7% on EAT-26, 24% on an ARFID screen and 21% for orthorexia. Only psychological distress and symptom severity predicted ARFID and orthorexia risk. Eating pattern, measured FODMAP intake and time since education did not. No new eating disorder diagnoses were found [12].
Population
74 people with IBS taught the diet by a dietitian, 84% women, median age 59 [12].
Sources
[12]
Caveats
Cross-sectional, with no comparison group of people with IBS who were never taught the diet [12].

Mixed results1

Limited

Diet quality and nutrient intake

Diet quality scores fell after 4 weeks on the diet in IBS, while intake of most nutrients did not change over 4 to 12 weeks.

The numbers and sources
Effect
In 130 adults with IBS, intake of most nutrients on the diet did not differ from controls after 4 weeks. Starch intake was lower (109 against 128 g a day on habitual diet) and vitamin B12 higher, and overall diet quality scores were lower than on habitual diet (P < 0.01) [11]. Over 12 weeks of a strict version, blood measures stayed within reference ranges and macro- and micronutrient intakes did not change, though several were below recommendations both before and after [9].
Population
130 adults with IBS in 2 randomized trials [11]; 36 adults with diarrhea-predominant or mixed IBS completing 12 weeks [9].
Sources
[9], [11]
Caveats
Short studies. Shortfalls were present before the diet: only 5% of people with IBS met the 30 g a day fiber target at baseline [11].

Claims tested and not found

  1. That the diet lowers gut inflammation in inflammatory bowel disease. Fecal calprotectin and the Mayo score did not differ [6].
  2. That the diet reduces gut microbiome diversity. Across 9 trials there were no clear effects on diversity [10].

Sources

  1. Black CJ, Staudacher HM, Ford AC. Efficacy of a low FODMAP diet in irritable bowel syndrome: systematic review and network meta-analysis. Gut. 2021. https://doi.org/10.1136/gutjnl-2021-325214
  2. van Lanen AS, de Bree A, Greyling A. Efficacy of a low-FODMAP diet in adult irritable bowel syndrome: a systematic review and meta-analysis. European Journal of Nutrition. 2021. https://doi.org/10.1007/s00394-020-02473-0
  3. Dionne J, Ford AC, Yuan Y, et al. A Systematic Review and Meta-Analysis Evaluating the Efficacy of a Gluten-Free Diet and a Low FODMAPs Diet in Treating Symptoms of Irritable Bowel Syndrome. The American Journal of Gastroenterology. 2018. https://doi.org/10.1038/s41395-018-0195-4
  4. Staudacher HM, Lomer MCE, Farquharson FM, et al. A Diet Low in FODMAPs Reduces Symptoms in Patients With Irritable Bowel Syndrome and A Probiotic Restores Bifidobacterium Species: A Randomized Controlled Trial. Gastroenterology. 2017. https://doi.org/10.1053/j.gastro.2017.06.010
  5. Pouladi A, Arabpour E, Bahrami O, et al. Impacts of the Long-Term Low-FODMAP Diet in Patients With Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis. Journal of Human Nutrition and Dietetics. 2025. https://doi.org/10.1111/jhn.70105
  6. Peng Z, Yi J, Liu X. A Low-FODMAP Diet Provides Benefits for Functional Gastrointestinal Symptoms but Not for Improving Stool Consistency and Mucosal Inflammation in IBD: A Systematic Review and Meta-Analysis. Nutrients. 2022. https://doi.org/10.3390/nu14102072
  7. Souza PHSO, Coêlho JRC, de Andrade AM, et al. Low-FODMAP diet for pediatric patients with disorders of gut-brain interaction: A systematic review and meta-analysis. Journal of Parenteral and Enteral Nutrition. 2026. https://doi.org/10.1002/jpen.70135
  8. Staudacher HM, Lomer MC, Anderson JL, et al. Fermentable carbohydrate restriction reduces luminal bifidobacteria and gastrointestinal symptoms in patients with irritable bowel syndrome. The Journal of Nutrition. 2012. https://doi.org/10.3945/jn.112.159285
  9. Hillestad EMR, Steinsvik EK, Teige ES, et al. Nutritional safety and status following a 12-week strict low FODMAP diet in patients with irritable bowel syndrome. Neurogastroenterology & Motility. 2024. https://doi.org/10.1111/nmo.14814
  10. So D, Loughman A, Staudacher HM. Effects of a low FODMAP diet on the colonic microbiome in irritable bowel syndrome: a systematic review with meta-analysis. The American Journal of Clinical Nutrition. 2022. https://doi.org/10.1093/ajcn/nqac176
  11. Staudacher HM, Ralph FSE, Irving PM, et al. Nutrient Intake, Diet Quality, and Diet Diversity in Irritable Bowel Syndrome and the Impact of the Low FODMAP Diet. Journal of the Academy of Nutrition and Dietetics. 2020. https://doi.org/10.1016/j.jand.2019.01.017
  12. Silva H, Knowles SR, Porter J, et al. Disordered Eating Behaviors Many Years After Education in a Low FODMAP Diet in Patients With Irritable Bowel Syndrome. JGH Open. 2026. https://doi.org/10.1002/jgh3.70467

Everything in the library