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The low FODMAP diet is a short-term elimination and reintroduction plan for people with diagnosed irritable bowel syndrome (IBS). FODMAPs are short-chain carbohydrates that are poorly absorbed in the small intestine and fermented by gut bacteria, which can bring on pain, bloating, gas and bowel changes in people with a sensitive gut. Researchers at Monash University in Australia developed the approach. It has three phases: cut back on high-FODMAP foods for a few weeks, reintroduce them one group at a time, then settle on a personal long-term diet. US gastroenterology groups describe it as the most evidence-based diet for IBS, but they also stress that it works most reliably with a dietitian and is not meant to be permanent.
Peptide Labs sells fiber products whose labels list FODMAP ingredients, but this article does not recommend any of them. It is general information, not medical advice; anyone with ongoing gut symptoms should work with a clinician or dietitian.
Key Takeaways
- FODMAPs are fermentable carbohydrates: fructans and GOS, lactose, excess fructose and polyols.
- The diet has three phases: restriction for a few weeks, reintroduction, then personalization.
- The American College of Gastroenterology recommends a limited trial for IBS; the AGA calls it the most evidence-based IBS diet.
- About three in four people with IBS improve, by Monash's count; the rest need other approaches.
- Long-term strict restriction is not the goal, and it lowers beneficial Bifidobacteria in the gut.
What is FODMAP?
FODMAP is an acronym for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. According to Monash University, these sugars move slowly through the small intestine, drawing in water, and are then fermented by bacteria in the large intestine, producing gas. That happens in everyone, and most people eat high-FODMAP foods every day without trouble. In people with IBS, a sensitive gut wall or altered gut movement can turn that extra water and gas into pain, bloating, wind and diarrhea or constipation.
- Oligosaccharides: fructans and galacto-oligosaccharides (GOS), found in wheat, rye, onions, garlic and legumes.
- Disaccharides: lactose, found in milk, soft cheeses and yogurt.
- Monosaccharides: excess fructose, found in honey, apples and high fructose corn syrup.
- Polyols: sorbitol and mannitol in some fruits and vegetables, plus sweeteners ending in -ol such as xylitol and maltitol.
FODMAP foods: higher and lower examples
Monash warns that you cannot guess a food’s FODMAP content and that many online lists are inaccurate; its team measures foods in the lab and rates them red, amber or green in its app. These examples come from Monash’s own sample list:
| Food group | Higher in FODMAPs | Lower-FODMAP alternatives |
|---|---|---|
| Vegetables | Artichoke, asparagus, cauliflower, garlic, mushrooms, onion | Eggplant, green beans, bok choy, carrot, cucumber, lettuce, potato, zucchini |
| Fruit | Apples, cherries, dried fruit, mango, pears, watermelon | Cantaloupe, green kiwi fruit, mandarin, orange, pineapple |
| Dairy and alternatives | Cow's milk, custard, ice cream, yogurt | Lactose-free milk, hard cheeses, feta, almond milk, soy milk made from soy protein |
| Protein | Most legumes, some marinated or processed meats | Eggs, firm tofu, tempeh, plain cooked meat, poultry and seafood |
| Breads and cereals | Wheat, rye and barley breads, cereals and snacks | Oats, corn flakes, quinoa, rice cakes, sourdough spelt bread |
| Sweeteners | Honey, high fructose corn syrup, sugar-free confectionery | Maple syrup, rice malt syrup, table sugar, dark chocolate |
| Nuts | Cashews, pistachios | Macadamias, peanuts, walnuts, pumpkin seeds |
Two details often surprise people. Dairy is not banned: butter and hard cheeses are naturally low in lactose, and Monash says to choose calcium-fortified plant milks because they do not contain calcium naturally. And sugar-free candy and gum are often high in FODMAPs, because NIDDK lists sorbitol, mannitol, xylitol and maltitol among foods to watch; our guide to sugar alcohols explains why these sweeteners cause gas. People who digest lactose well may not need to limit it at all; our guide to lactase covers lactose-free options and enzyme pills.
The three phases of a low FODMAP diet
- Restriction. High-FODMAP foods are swapped for lower-FODMAP alternatives. Monash suggests two to six weeks, and the AGA says no more than four to six. If symptoms do not improve, Monash advises moving on to other approaches, because your symptoms may not be FODMAP-sensitive.
- Reintroduction. FODMAP groups are tested one at a time. In Monash’s version, you eat a food rich in a single FODMAP group daily for three days while tracking symptoms, then record how well you tolerated it.
- Personalization. Well-tolerated foods come back, and poorly tolerated ones are limited only as much as needed. Monash suggests retesting problem foods over time, since tolerance can change.
The aim is the least restrictive diet that keeps symptoms manageable. Breath tests can sometimes show that a person absorbs lactose or fructose completely, which lets those groups stay in the diet.
What IBS guidelines and research say
| Source | Type | What it says | Limits |
|---|---|---|---|
| Halmos et al., Gastroenterology, 2014 | Crossover trial, 30 people with IBS and 8 controls | Overall symptom scores about half as high on a low FODMAP diet as on a typical Australian diet | Three weeks per diet; nearly all food provided; Monash team |
| American College of Gastroenterology, 2021 | Clinical guideline | Recommends a limited trial of a low FODMAP diet in IBS to improve global symptoms | Guideline wording; individual results vary |
| American Gastroenterological Association, 2022 | Expert review | Most evidence-based IBS diet; three phases; refer to a registered dietitian | Not a systematic review; no formal evidence grading |
| So et al., American Journal of Clinical Nutrition, 2022 | Meta-analysis, 9 trials, 403 people | Consistently lower Bifidobacteria; no clear change in microbiome diversity | Small trials; larger studies needed |
The most cited early trial came from the Monash group itself. In a 2014 single-blind crossover study, 30 people with IBS ate a low FODMAP diet and a typical Australian diet for three weeks each, with almost all food provided. Overall symptom scores were about half as high on the low FODMAP diet, with less bloating, pain and wind, while the eight people without IBS felt no difference. Monash reports that about three in four people with IBS improve, which also means about one in four do not.
The American College of Gastroenterology’s first IBS guideline, published in 2021, recommends a limited trial of a low FODMAP diet to improve overall symptoms. The American Gastroenterological Association’s 2022 expert review goes further in calling it the most evidence-based diet for IBS, while adding that soluble fiber also helps overall IBS symptoms and that gluten-free diet trials have been mixed. Both frame it as a time-limited trial, not a lifelong diet.
The main research concern is the gut microbiome. A 2022 meta-analysis of nine randomized trials found that the diet consistently lowered Bifidobacteria, a group of bacteria usually seen as beneficial, although it did not clearly change overall diversity or short-chain fatty acids. That is one reason experts stress reintroduction rather than staying on strict restriction.
Who should not start the diet on their own
Monash says the diet is meant for people with medically diagnosed IBS. Celiac disease, inflammatory bowel disease, endometriosis and bowel cancer can cause similar symptoms, so self-diagnosis is risky; see a clinician for new or changing symptoms, weight loss or blood in the stool. The AGA lists people who are poor candidates for restrictive diets: those who eat few trigger foods, those at risk of malnutrition, people facing food insecurity, and anyone with an eating disorder or an uncontrolled psychiatric condition. It also recommends routine screening for disordered eating.
The diet was designed to manage IBS symptoms, not to lose weight, and the original researchers say it needs expert delivery by a trained dietitian. Monash keeps a directory of dietitians who have completed its FODMAP training.
Fiber and product labels on an IBS diet
Restriction removes many fiber-rich foods, such as wheat breads, legumes and some fruits, so fiber can drop without anyone noticing. NIDDK notes that soluble fiber seems more helpful for IBS symptoms than insoluble fiber and that fiber should be added slowly, because too much at once causes gas. Our guide to how much fiber per day covers daily targets. Lower-FODMAP sources of fiber, such as oats, potatoes, carrots and oranges, appear on the Monash list above.
Fiber supplements deserve a label check during an IBS diet, because several common ingredients are FODMAPs. Inulin, chicory root fiber and fructooligosaccharides are fructans, as our inulin guide explains, and sorbitol, maltitol and xylitol are polyols. Three labels we carry show how this looks:
- MiraFIBER Gummies get their fiber from inulin, and the label says to reduce the daily serving if gas, bloating or stomach upset occurs.
- Nature Made Probiotic + Prebiotic Fiber Gummies list inulin from chicory root and maltitol as their first two ingredients.
- Benefiber Chewables use wheat dextrin as the fiber and list sorbitol as the second ingredient.
None of this makes these products unsafe; it means people in the restriction phase should show labels to their dietitian. Probiotics for IBS are still being studied, according to NIDDK; our guides to probiotics for bloating and debloating cover the evidence and other everyday steps.
Frequently Asked Questions
What is FODMAP?
FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols, a group of short-chain carbohydrates that are poorly absorbed and fermented by gut bacteria.
How long do you stay in the restriction phase?
Monash suggests two to six weeks, and the AGA says no more than four to six weeks, followed by reintroduction. If symptoms do not improve, a different approach is usually considered.
Is the low FODMAP diet a weight-loss diet?
No. It was designed to manage symptoms of diagnosed IBS, and any weight change is not its purpose.
Do you have to give up dairy?
Not necessarily. Lactose-free milk, butter and hard cheeses are low in lactose, and people who digest lactose well may not need to limit it.
Does the low FODMAP diet work for everyone with IBS?
No. Monash reports that about three in four people improve; the rest need other approaches, which a clinician can discuss.
Should I try it without a dietitian?
US gastroenterology groups and Monash advise working with a dietitian, and getting a diagnosis first, because other conditions can mimic IBS and restriction can cut nutrients.
Questions about a label? Contact us or read our Buyer’s Guide. Follow the label and ask a healthcare provider before starting any supplement, especially if you take medicines. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Last reviewed October 2026.
Related guides: Sugar Alcohols: Xylitol, Diarrhea, Blood Sugar and Labels, Prebiotic Fiber Supplements: Inulin, FOS and What the Research Shows, How to Debloat: Common Causes of Bloating, What Helps and When to See a Doctor.