Low-FODMAP Diet

Diet Reference Archive: a therapeutic diet used under clinical guidance

Low-FODMAP Diet

A 3-step eating plan that first cuts back a group of poorly absorbed carbohydrates called FODMAPs, then adds them back one group at a time to learn which ones a person tolerates. It is used mainly to ease the symptoms of irritable bowel syndrome after a clinician has diagnosed it, and its strict first step is meant to last weeks, not a lifetime.

Family: Therapeutic and elimination diets Promoted by: researchers at Monash University in Australia, and gastroenterology dietitians First appeared: the name in 2005; the first controlled trials from 2008 CINeMA: Moderate for short-term relief of overall symptoms in adults with irritable bowel syndrome, low-FODMAP restriction against usual eating, direct trial evidence; published rating, Cuffe et al., 2025

ON THIS PAGE

1. In brief
2. Overview
3. In practice
4. For the coach
5. The evidence (opens on request)
6. Mechanisms (opens on request)
7. Risks, contraindications and myths (opens on request)
8. Key terms
9. Review questions
10. References
11. Evidence rating and review record

The summary and sections 1 to 3 are the short version and are open when the page loads. Sections 4 to 6 hold the research detail, the biology, and the cautions. Each of those opens when you select its heading, and you can read the page without opening them. Back to the Diet Reference Archive index.

In brief

What is it? A short-term, structured way of eating for people whose irritable bowel syndrome has been diagnosed by a clinician. For 2 to 6 weeks the person swaps foods high in certain fermentable carbohydrates, such as wheat, onion, garlic, beans, milk, apples and some sweeteners, for lower ones. Then, usually with a dietitian, they add those carbohydrates back one group at a time to find which ones bother them, and settle into a personal pattern that limits only what they need to.

Does it work? For many adults with irritable bowel syndrome, yes, for symptoms. In 24 trials analyzed in a 2025 review, people who followed the restriction step for a few weeks were about half as likely as people on their usual diet to say their overall symptoms had not improved, and the review rated the direct trial evidence at moderate confidence. The review also reports improvements in pain and bloating. The published appendix rates the direct comparison with ordinary dietary advice Low on the CINeMA scale; its separate network estimate remains provisional and is withheld. It does not cure the condition; its developers say about 1 in 4 people do not improve on it. Long-term evidence comes mostly from follow-up studies without comparison groups. It is not a weight-loss diet, and the searches for this page found no study of it as a way to prevent any disease.

Is it safe? When a trained dietitian guides it for a few weeks, the trials that reported harms found few, and a U.S. guideline describes it as seeming safe without serious adverse events, although most trials did not report harms in detail. The cautions come from staying in the strict step too long or doing it alone. Over the longer term, strict restriction can lower fiber, calcium and some B vitamins and can make eating out and family meals harder. Short trials also found lower fecal Bifidobacteria, one group of gut bacteria; what this means for health is unknown. For someone prone to disordered eating, a list of foods to avoid can become a set of rules.

Who should not do it without talking to a doctor or dietitian first? Anyone whose gut symptoms have not been diagnosed, since celiac disease, inflammatory bowel disease and other conditions cause similar symptoms. Anyone with blood in the stool, weight loss they did not intend, or new symptoms later in life. Anyone with a current or past eating disorder. Children and teenagers, people who are pregnant, older adults, anyone already on another restrictive diet, and anyone taking a diabetes medicine that can lower blood sugar.

Related pages: Anti-Inflammatory Diet, Gluten-Free Diet and Elimination Diets. Full list on the archive index.

1. Overview

What you eat

FODMAP is an acronym for 4 kinds of short-chain carbohydrate: fermentable oligosaccharides, disaccharides, monosaccharides and polyols. In practice they are fructans and galacto-oligosaccharides, found in wheat, rye, onion, garlic, beans and lentils; lactose, the sugar in milk; fructose in foods that carry more of it than glucose, such as honey and apples; and the sugar alcohols sorbitol and mannitol, found in some fruit and vegetables and used as sweeteners. Most people eat these every day without trouble (Monash University, n.d.-a).

In the first step a person eats foods that are low in all of these, in measured servings. The Monash University team, which developed the diet, lists eggs, firm tofu, tempeh and plain cooked meat, poultry and seafood among low-FODMAP protein foods; oats, quinoa, rice and corn pasta, and spelt sourdough bread among grain foods; carrot, cucumber, eggplant, green beans, lettuce, potato and zucchini among vegetables; cantaloupe, kiwi fruit, mandarin, orange and pineapple among fruit; and lactose-free milk, almond milk, feta and hard cheeses among dairy foods and alternatives. Serving size matters, because some foods are low in a small serving and high in a larger one (Monash University, n.d.-a, n.d.-b).

A Monash research dietitian describes the first step as a substitution diet rather than an elimination diet: the person swaps a high-FODMAP food for a low one, such as an orange for an apple or chives for onion (Dwyer, 2018). The second and third steps add foods back, so that the long-term diet limits only what an individual reacts to.

What you avoid or limit

During the first step, the Monash team lists among high-FODMAP foods artichoke, asparagus, cauliflower, garlic, green peas, mushrooms, onion and sugar snap peas; apples, cherries, dried fruit, mango, nectarines, peaches, pears, plums and watermelon; cow's milk, ice cream and yogurt; most beans and lentils; bread, cereal and snack foods based on wheat, rye or barley; cashews and pistachios; and honey, high-fructose corn syrup and sugar-free sweets made with sugar alcohols. Marinades, sauces and gravies can hide onion and garlic (Monash University, n.d.-a, n.d.-b).

The limits are firm for a short time and then deliberately loosened. The program's developers set the restriction step at 2 to 6 weeks, followed by a structured reintroduction and then a personal long-term pattern (Dwyer, 2018). The American Gastroenterological Association describes the same 3 phases, with restriction lasting no more than 4 to 6 weeks (Chey et al., 2022), and the American College of Gastroenterology describes all 3 and notes that people who respond to restriction can be identified in 2 to 6 weeks (Lacy et al., 2021). A person who never leaves the first step is not following the diet as designed.

Where it came from

The name came from gastroenterology researchers at Monash University in Melbourne. In 2005, Peter Gibson and Susan Shepherd grouped these poorly absorbed, rapidly fermented carbohydrates under the label FODMAPs in a paper that proposed, as a hypothesis, that a rising intake of them might help explain susceptibility to Crohn's disease (Gibson & Shepherd, 2005).

The idea found its use in a different condition. In 2006 the same team reported that 46 of 62 patients with irritable bowel syndrome and fructose malabsorption improved in all their abdominal symptoms on a diet low in fructose and fructans, an outcome gathered by telephone interview months to years later rather than in a trial (Shepherd & Gibson, 2006). In a placebo-controlled rechallenge trial published in 2008, 25 patients who had improved on that diet were given fructose, fructans, a mixture of both, or glucose in drinks with their meals; most reported poorly controlled symptoms on the first 3 and few on glucose (Shepherd et al., 2008).

The team then measured the FODMAP content of a wide range of foods and built the first low-FODMAP diet from those measurements (Monash University, n.d.-e). In a controlled trial published in 2014, almost all food was supplied to participants (Halmos et al., 2014); it is described in section 4. Monash distributes its food data through a smartphone app, trains dietitians, and has run a certification program for low-FODMAP food products since 2014 (Monash University, n.d.-c, n.d.-d). Clinical guidelines in the United States and the United Kingdom now include the diet among treatments for irritable bowel syndrome (Lacy et al., 2021; Vasant et al., 2021).

What it claims to do

Monash University states that its research showed irritable bowel syndrome symptoms improve in 3 out of 4 people who follow a low-FODMAP diet, that a low-FODMAP diet has been shown to reduce pain and discomfort, reduce bloating and distension, improve bowel habit and improve quality of life, and that these benefits are usually seen within 2 to 6 weeks. It also states that the diet is "now recommended as the first treatment choice" for people diagnosed with irritable bowel syndrome (Monash University, n.d.-a). The same page says the diet does not cure irritable bowel syndrome and that 1 in 4 people do not improve on it.

Clients bring broader claims they have met elsewhere: that the diet heals the gut, that it is a healthy way for anyone to eat, that it helps with weight, or that it is a good first step for any bloating. Section 4 describes what the evidence shows for the claims about symptoms, and section 6 takes up the broader ones.

What it gets right

It treats food-related symptoms as real and testable. Many people with irritable bowel syndrome connect their symptoms with eating, and this approach gives them a structured way to find out which foods matter for them instead of guessing or cutting foods at random. Its design, a short restriction followed by deliberate reintroduction, is aimed at the least restrictive diet that still controls symptoms, and that aim is sound.

It also has a real evidence base for what it is used for. In a 2025 review of 28 randomized trials of diets for irritable bowel syndrome, 24 trials were analyzed in the low-FODMAP group, including one that combined the diet with traditional dietary advice, far more than for any other diet (Cuffe et al., 2025). That is what lets a coach honor a client's reasons for trying it, while leaving the decision about whether and how to use it to the client and their clinical team.

How clients describe it, and what it gets confused with

Clients say "I'm doing FODMAP," "I can't have onion or garlic," "my GI doctor sent me to a dietitian for my IBS," "I'm in the challenge phase," "I use the Monash app," or "I found a FODMAP list online and I'm just avoiding everything on it." The last of these is worth noticing, because a list without the reintroduction steps is not the full 3-step program as its developers designed it.

It is most often confused with a gluten-free diet, because wheat, rye and barley are cut back in the first step; with lactose-free or dairy-free eating, because milk and soft dairy foods are limited; with general elimination diets and the specific carbohydrate diet; and with low-carbohydrate eating, although the diet is not low in carbohydrate as a whole. Separate Gluten-Free Diet, Elimination Diets, Dairy-Free Diet and Specific Carbohydrate Diet pages are listed on the archive index.

2. In practice

A typical day of eating

A day in the first step might start with oatmeal made with lactose-free milk, topped with a few walnuts, a sliced kiwi fruit and a little maple syrup. Lunch is a sandwich on spelt sourdough bread with sliced chicken, lettuce and cucumber, with an orange. An afternoon snack is a plain rice cake and a small handful of peanuts or macadamias, and water is the usual drink. Dinner is grilled salmon or firm tofu with rice and roasted carrots, zucchini and potato, cooked in olive oil infused with garlic and finished with chives instead of onion. A day on the personalized diet that follows might look much like an ordinary one, with only the foods that bothered that person, in the amounts that bothered them, still limited.

Cost, products, and who profits

The diet needs no supplement or membership, and many low-FODMAP staples, such as rice, oats, potatoes, eggs, carrots and canned fish, are inexpensive. Specialty versions of everyday foods cost more. A 2015 Monash price comparison in one large Australian supermarket found low-lactose milk cost more than twice as much as regular milk and gluten-free bread 7 times as much as regular wheat bread, per 100 grams (Varney, 2015a). In trials, people reported that the diet cost more than ordinary dietary advice for irritable bowel syndrome and took longer to shop for (Rej et al., 2022), and people who stayed on an adapted version of it long term reported higher costs than people who had gone back to their usual diet (O'Keeffe et al., 2018).

Money attaches to the diet in several places. The Monash smartphone app costs about 8 U.S. dollars as a one-time purchase, with proceeds going to further food testing and research, and Monash sells an online course for patients for 60 U.S. dollars outside Australia and training for dietitians (Monash University, n.d.-d, n.d.-g). Its certification program tests food companies' products, which may then carry the Monash certified logo (Monash University, n.d.-c), and enzyme products such as lactase drops are sold to help digest particular FODMAPs (Monash University, n.d.-b). Dietitian visits, which most guidelines recommend, cost money and are not equally available; one English hospital found group teaching about as effective as one-to-one teaching (Whigham et al., 2015).

For someone with limited money or time, the cheaper path runs through ordinary foods rather than specialty products. Monash's own suggestions include cooking in bulk, using frozen vegetables and berries, choosing eggs, canned fish, rice and potatoes, and making low-lactose milk at home with lactase drops (Varney, 2015a).

Environmental footprint

The searches for this page found no study of the environmental footprint of this diet. Its first step changes which fruits, vegetables, grains, legumes and dairy foods a person eats, more than how much animal food they eat, so the footprint depends mostly on what a person chooses within it. Across modeling studies of more sustainable diets, the reductions in greenhouse gas emissions, land use and water use generally tracked how much animal food was cut (Aleksandrowicz et al., 2016), so a person who replaces beans and lentils with meat would be expected to move toward a larger footprint, and one who uses firm tofu, tempeh and small servings of canned legumes would not. Those are modeled estimates, not measurements of people on this diet.

Cultural fit

The fit depends on the cuisine. Onion and garlic are everyday ingredients in many cuisines, wheat breads, noodles and flatbreads are staples in many, and beans, lentils and chickpeas supply much of the protein in many vegetarian traditions. The first step asks for changes to exactly these foods. Monash suggests ways to keep flavor and protein, such as garlic-infused oil, the spice asafoetida, the green tops of spring onions, and rinsed canned chickpeas or lentils in small servings (Monash University, n.d.-b; Varney, 2015c). It also states that it keeps adding foods from other countries to its app (Monash University, n.d.-d), so a food common in one cuisine may not yet be listed.

Because the restriction is short and the long-term diet is personal, most food traditions can be kept largely intact after reintroduction. That depends on the person reaching the reintroduction step, which is where a dietitian who knows the person's cuisine is most useful.

What makes people stop

In a German clinic study, 30 of the 63 patients taught the diet stopped it, and 33 completed the assessment 8 weeks after starting (Frieling et al., 2019). In an English randomized trial, people found ordinary dietary advice for irritable bowel syndrome cheaper, quicker to shop for, easier when eating out and easier to fit into daily life than the low-FODMAP diet (Rej et al., 2022). People who kept to an adapted version long term reported that it affected eating with others (O'Keeffe et al., 2018), and a Monash research dietitian describes the strict step as inconvenient and socially difficult to follow (Varney, 2015b).

The opposite problem is common too: people who feel better may not want to add foods back. In an Australian follow-up of 74 patients taught the diet by a specialist dietitian, all were taught the restriction step but only 23 percent were guided by a dietitian through reintroduction and personalization, and 12 percent were still following a strict low-FODMAP diet a mean of 7 years later (Silva et al., 2025). Beyond those figures, what follows is observation rather than measured data: reintroduction asks a person to eat foods they have come to connect with their symptoms, which is hard for someone who finally feels better.

What happens when you stop

The diet is designed to stop: the restriction step ends, and foods come back. In the Swedish CARIBS trial, participants received reintroduction instructions after the 4-week restriction. At 6 months, symptom outcomes did not clearly differ between its 2 dietary groups. Participants knew their diets by then, and follow-up was incomplete, so this does not establish the long-term effect of low-FODMAP restriction against usual eating (Nybacka et al., 2024).

Follow-up studies without comparison groups, described in section 4, suggest that most people who are taught the diet well keep limiting a few FODMAPs rather than returning fully to their old diet, and that more than half still report satisfactory relief at longer follow-up (O'Keeffe et al., 2018; Silva et al., 2025). In the Australian group followed for a mean of 7 years, 26 percent had returned to their usual diet, 62 percent were on a personalized diet and 12 percent were still strict; symptoms were similar across these groups, but those still strict reported lower food-related quality of life (Silva et al., 2025). Monash advises that a person who eats too many FODMAPs and has symptoms can return to the strict step and that symptoms should improve within 1 to 3 days (Monash University, n.d.-b).

Common variations

A "FODMAP-gentle" diet limits only a handful of foods very concentrated in FODMAPs rather than every high-FODMAP food (Halmos & Gibson, 2019), such as wheat and rye products, onion, garlic, apples, pears, milk and legumes. Monash dietitians suggest it for people who are already malnourished or have recently lost weight without meaning to, people with other dietary restrictions, children, older adults, people who are pregnant, and people who find the full diet too hard (Collins & Halmos, 2020). The published appendix also lists 1 trial of a FODMAP-simple diet (Cuffe et al., 2025).

The diet is also taught in groups (Whigham et al., 2015) and through a smartphone app, which was tested against a medication in a Belgian primary care trial described in section 4 (Carbone et al., 2022). Some programs combine it with ordinary dietary advice for irritable bowel syndrome (Nybacka et al., 2024). Outside irritable bowel syndrome, it has been studied for persistent gut symptoms in people whose inflammatory bowel disease is in remission (Cox et al., 2020), for gut symptoms in endometriosis (Watrowski et al., 2026) and, briefly, in runners with exercise-related gut symptoms (Lis et al., 2018; Wiffin et al., 2019). Each of these is its own question, and none of them turns the diet into a general way of eating.

3. For the coach

SCOPE OF PRACTICE

A health and wellness coach does not prescribe, adjust, endorse or discourage this or any way of eating, and does not diagnose or treat. The coach helps the client understand what they have chosen, notice how it is going, and decide what to do next. This diet sits more firmly on the clinical side than most, for 3 reasons.

First, it treats a diagnosed condition. Irritable bowel syndrome shares symptoms with celiac disease, inflammatory bowel disease and other conditions, so a client with gut symptoms but no diagnosis needs a clinician before any diet, and the coach does not guess at what symptoms mean. Second, the guidelines that recommend it say a dietitian or other professional with expertise in dietary management should teach and supervise it; a client asking which foods to cut, which to add back or how much to eat is asking for a dietitian's work. Third, restrictive diets call for particular care in people prone to disordered eating. A coach notices and asks what a restriction is for, and whether it causes distress, narrows eating or disrupts daily life, while recognizing ordinary explanations such as waiting for an appointment. A real concern goes through the coach's own referral process, or to the client's existing clinician.

Who does what

The physician

Makes the diagnosis of irritable bowel syndrome, which a U.S. guideline recommends doing positively from the symptom history and examination with limited testing, rather than only by ruling out everything else. For people with diarrhea symptoms that guideline suggests blood tests for celiac disease and tests of stool or blood to look for inflammatory bowel disease, and it lists the warning signs that call for more investigation (Lacy et al., 2021). Usually a primary care physician or gastroenterologist. Decides on any medication for irritable bowel syndrome, adjusts medication the diet might affect, such as diabetes medicine that can lower blood sugar, and refers to a dietitian.

The registered dietitian

Usually a dietitian with training in gastrointestinal conditions and this diet. Checks first whether the person is a suitable candidate, including a careful history for disordered eating and nutrition risk (Chey et al., 2022). Decides whether the full diet or a gentler version fits, teaches the restriction step, sets its length, and leads the reintroduction challenges, which test one FODMAP group at a time over a few days each (Monash University, n.d.-f). Interprets the results and builds the long-term personalized diet, and checks that the restricted diet still meets the person's needs for fiber, calcium and other nutrients.

The health and wellness coach

Helps the client get ready for and make use of their clinical care: clarifying what they want from the diet, what they want to ask the dietitian, and how they will keep the appointments that carry them through reintroduction. Helps with the practical habits the dietitian's plan depends on, such as planning meals, shopping, cooking at home, eating out and handling family meals, using the plan the client brings rather than a new one. Explores how the diet fits the client's values, culture, budget and social life, and how the client is managing stress and the other parts of daily life that affect them. Notices whether eating is widening or narrowing over time, and holds the referral line when a question belongs to a clinician.

What a client bringing this diet needs

Clients usually arrive at one of 3 points. Some have just been diagnosed and told about the diet, and feel overwhelmed by a list of foods they cannot eat. Some are in the middle of it, feeling better on restriction and unsure about, or afraid of, adding foods back. And some found a FODMAP list online and are following it on their own, sometimes without a diagnosis. Each needs something different from the coach: a steady place to plan, encouragement to use the dietitian for the parts that belong to the dietitian, or a conversation about getting the symptoms checked before going further.

What coaching adds that a search engine cannot is room to look at the person's whole life around the diet. Food is only one part of managing irritable bowel syndrome; a U.S. guideline also includes medication, soluble fiber, and gut-directed psychotherapies such as cognitive behavioral therapy and gut-directed hypnotherapy delivered by trained clinicians (Lacy et al., 2021). A coach can help a client see the diet as one tool among several and decide what to raise with their clinical team.

What to ask

• What did your doctor or dietitian tell you about how long the first step should last, and what happens after it?
• What would you want your eating to look like once you know which foods bother you?
• How is this way of eating fitting with the people you eat with, your budget and your week?

Referral red flags

A client with gut symptoms that have not been diagnosed by a clinician, who wants to start this diet, goes to their clinician first. Monash University, the program's developer, states plainly that a person without a medical diagnosis "should not be following this diet" (Monash University, n.d.-a). The same is true when symptoms change or new ones appear while a client is on the diet. A U.S. guideline lists warning signs that call for clinical investigation: blood in the stool or black stool, weight loss the person did not intend, symptoms that begin at an older age, and a family history of inflammatory bowel disease, colon cancer or other significant gut disease (Lacy et al., 2021). The coach does not judge what any of these means; the client tells their clinician.

A client who has stayed in the strict step well beyond the few weeks their dietitian planned, who has skipped the reintroduction appointments, or whose list keeps getting longer is worth asking about it: what each restriction is for, whether it causes distress, whether it is narrowing what they eat, and whether it is getting in the way of meals with other people. There are ordinary reasons for some of this, such as waiting for an appointment. Where the answers raise a real concern about disordered eating, the coach follows their own referral process, or, for a client already in care, encourages them to tell their clinician or dietitian.

A client taking insulin or another diabetes medicine that can lower blood sugar, who is making a substantial change in what they eat, keeps their prescriber informed before making it.

Special populations

Pregnancy and breastfeeding

The searches for this page found no trial during pregnancy. A Monash research dietitian writes that the team has not studied the diet in pregnant women, does not recommend it as a dietary therapy for pregnancy, and that "it is not a diet that should be commenced during pregnancy" (Iacovou, 2016). A small trial tested a low-FODMAP diet in breastfeeding mothers for infant colic, rather than maternal irritable bowel syndrome or the long-term safety of restriction (Iacovou et al., 2018). Questions about the diet during pregnancy or breastfeeding belong to the person's clinician and a dietitian.

Children and adolescents

A 2025 European and North American guideline for children aged 4 to 18 with irritable bowel syndrome or functional abdominal pain suggested against a strict low-FODMAP diet, because the trials did not support any conclusion about benefit at even low certainty, and it cautioned that restrictive diets can harm growing children's nutrition and relationship with food (Groen et al., 2025). The trials are small and short: in 33 children with irritable bowel syndrome, pain episodes were fewer during 48 hours on the diet than during 48 hours on a typical American childhood diet (Chumpitazi et al., 2015). A child's eating belongs to the family and the child's clinicians.

Older adults

In 20 adults over 65 with chronic diarrhea and no cause found on colonoscopy, 6 weeks of the diet taught by a dietitian improved gut symptoms without clinically significant changes in nutrient intake, in a study with no comparison group (O'Brien et al., 2020). New gut symptoms at an older age are a warning sign for the clinician first (Lacy et al., 2021), and Monash dietitians suggest the gentler version for older adults (Collins & Halmos, 2020). Whether a restricted diet meets an older adult's nutrient needs is a question for a dietitian.

Athletes and people with high activity

Runners with exercise-related gut symptoms but no diagnosis of irritable bowel syndrome have been studied briefly. In 11 runners, 6 days on a low-FODMAP diet reduced daily gut symptoms compared with a high-FODMAP diet, but not symptoms during exercise (Lis et al., 2018); in 16 recreational runners, 7 days lowered symptom scores compared with a high-FODMAP diet (Wiffin et al., 2019). These compared low with deliberately high intake, not with usual eating, for about a week. Fueling for hard training is a sports dietitian's question.

People taking medication for diabetes, blood pressure, or blood thinning

The searches for this page found no study of the diet's effect on these medications. In one U.S. trial, both the low-FODMAP diet and the comparison diet led people to eat fewer calories, fewer meals and less carbohydrate (Eswaran et al., 2020), which matters for anyone whose diabetes medicine can lower blood sugar. A client on insulin, a sulfonylurea, blood pressure medication or warfarin who plans a substantial change in eating keeps the prescriber informed before making it.

People with a history of disordered eating

This is the population the guidelines single out. The American Gastroenterological Association lists people with an eating disorder among poor candidates for restrictive diets and calls routine screening for disordered eating critical (Chey et al., 2022). In a population survey of 4,002 adults in the United Kingdom and the United States, positive screens for avoidant/restrictive food intake disorder, defined in the key terms, were more common among people with gut-brain disorders such as irritable bowel syndrome than among people without them, 34.6 percent against 19.4 percent (Flack et al., 2026). In one Australian follow-up, 38 percent of patients taught the diet years earlier showed disordered eating behaviors on screening, but these went with distress and symptom severity rather than with how strictly they now followed the diet, and no new eating disorder diagnoses were found (Silva et al., 2026). For a client with a current or past eating disorder, whether to try this diet is a decision for the clinical team.

Client misconceptions

Three come up most. The first is that the strict list is the diet, and that staying on it longer is better. The diet is designed to be strict for 2 to 6 weeks and then loosened, and its developers advise against following it for life because of its effects on fiber and nutrient intake, gut bacteria and social life (Varney, 2015b). The second is that it is a healthy diet for anyone, or a weight-loss diet. It was developed and tested for symptoms of diagnosed irritable bowel syndrome, and Monash states that it "is not intended as a weight loss plan" (Monash University, n.d.-a).

The third is that a food sensitivity test can show which foods to cut instead. A U.S. guideline states that the blood tests marketed to diagnose food intolerances have not been validated and that serum IgG panels cannot be recommended (Lacy et al., 2021). Reintroduction, guided by a dietitian, is how the diet finds a person's triggers. Each is addressed in section 6.

🤝 COACHING CONNECTION

Megan was diagnosed with irritable bowel syndrome last spring, and her dietitian started her on the low-FODMAP diet. Ten weeks later she tells her coach she feels better than she has in years, and that she cancelled her reintroduction appointment because she is afraid of feeling sick again. She has also stopped going to dinner with friends. The coach asks what feeling better has made possible for her. Megan says she can get through a workday without planning around a bathroom. The coach asks what she misses. Megan says pizza night with her friends, and her mom's lentil soup. The coach asks what she would want to happen next. Megan decides to call the dietitian and ask what the first challenge would look like, and to tell her friends she will come to pizza night and order something she knows. Nothing was recommended, and no food was evaluated.

4. The evidence

(select the heading to open or close this section)

The research on this diet is about one question above all: does a few weeks of FODMAP restriction ease the symptoms of irritable bowel syndrome in adults? Randomized trials report improvement over usual eating. The published appendix rates the direct comparison with usual eating Moderate and the direct comparison with traditional dietary advice Low on the CINeMA scale. The randomized intervention periods in the 4 highlighted studies lasted 3 or 4 weeks. Longer follow-up and the effect of reintroduction require separate consideration. The searches for this page found no trial of cardiovascular events, cancer incidence, progression or survival, or death.

Evidence from randomized controlled trials

A trial assigns people to the diet by chance and compares them with people assigned to something else, which is the strongest way to test whether the diet itself causes a result. Diet trials have a particular weakness here: symptoms are reported by the person, and it is hard to keep people from knowing that they are on a special diet. Trials handle this in different ways. Some supply all the food, some give the comparison group a sham diet that cuts a similar number of foods, and some compare the diet with another form of advice.

Symptoms of irritable bowel syndrome

The most recent synthesis, a 2025 network meta-analysis, gathered 28 randomized trials with 2,338 adults with irritable bowel syndrome, testing 11 different diets (Cuffe et al., 2025). A network meta-analysis combines trials that compared the same 2 treatments directly with trials that link them indirectly through a shared comparison. The review analyzed 24 trials in the low-FODMAP group, including one combined-diet intervention that paired the diet with traditional dietary advice. Compared with continuing their usual diet, people on the low-FODMAP diet were about half as likely to report that their overall symptoms had not improved: relative risk 0.51, 95 percent confidence interval 0.37 to 0.70, across 24 trials.

The authors rated their confidence in the overall symptom results with CINeMA, a framework for rating confidence in network meta-analyses that is broadly based on GRADE and uses its 4 levels, with some differences in method (Nikolakopoulou et al., 2020), and that the Cochrane Collaboration endorses. They rated the direct trial evidence comparing the low-FODMAP diet with usual eating at moderate confidence, and every other comparison in the network at low or very low confidence, apart from one other diet's direct comparison with usual eating (Cuffe et al., 2025). The headline figure above also draws on indirect comparisons. The published appendix's risk-of-bias table shows that no trial met every listed criterion (Cuffe et al., 2025).

For individual symptoms, the published abstract reports that the diet was better than usual eating for abdominal pain, relative risk of pain not improving 0.61 (0.42 to 0.89) in 23 trials, and for bloating or distension, 0.55 (0.37 to 0.80) in 23 trials. For bowel habit, the abstract reports no clear advantage for any dietary intervention over the control interventions (Cuffe et al., 2025).

The published main article could not be opened. Estimates and appraisal details found only in the authors' accepted manuscript remain provisional and are withheld here until they can be reconciled with the published article. The published abstract and the separately examined published appendix support the findings explicitly attributed to them.

An earlier meta-analysis used by the American College of Gastroenterology for its 2021 guideline pooled 7 trials with 397 patients and found that the diet reduced overall symptoms compared with a mix of comparison diets, relative risk 0.69 (0.54 to 0.88). The guideline judged every one of those trials at high risk of bias and rated the quality of evidence very low using GRADE, while still recommending a limited trial of the diet as a conditional recommendation (Lacy et al., 2021). The certainty ratings for these and other outcomes are in the review record at the end of this page.

Single trials show what lies behind these pooled numbers. In an Australian crossover trial, 30 adults with irritable bowel syndrome ate almost entirely supplied food for 21 days on a low-FODMAP diet and 21 days on a typical Australian diet, in random order. Overall symptom scores averaged 22.8 on a 100 mm scale on the low-FODMAP diet and 44.9 on the typical diet (Halmos et al., 2014). In an English trial with a sham diet that cut a similar number of foods, 57 percent of people on the low-FODMAP diet reported adequate relief of symptoms at 4 weeks against 38 percent on the sham diet, a difference that fell just short of statistical significance in the main analysis, while symptom severity scores were clearly lower (Staudacher et al., 2017).

The gut microbiome

FODMAPs feed gut bacteria, so cutting them changes the bacteria. A 2022 systematic review of 9 randomized trials in 403 patients with irritable bowel syndrome, most lasting 3 to 4 weeks, found one consistent effect: lower abundance of Bifidobacteria, a group of bacteria that can ferment fructans and are regarded as potentially beneficial. It found no clear effect on the overall diversity of the microbiome, on other specific bacteria, on the short-chain fatty acids that bacteria produce, or on stool acidity (So et al., 2022). The sham-controlled English trial above found the same drop in Bifidobacteria, and found that a probiotic given alongside the diet raised them (Staudacher et al., 2017). In people whose inflammatory bowel disease was in remission, 4 weeks of the diet also lowered several Bifidobacterium species and Faecalibacterium prausnitzii without changing markers of inflammation (Cox et al., 2020).

Whether these changes matter for health is not known. The review's authors note that Bifidobacteria have shown immune-regulating and anticancer properties in animal studies, but that is not evidence of harm in people (So et al., 2022). After reintroduction, the picture may change: in 18 patients seen 12 months after starting the diet and following a personalized version, Bifidobacteria did not differ from their levels before the diet, although short-chain fatty acids in stool were lower (Staudacher et al., 2022). That was a small study without a comparison group.

Nutrient intake and diet quality

Short trials with dietitian teaching found few changes in nutrient intake. Combining 2 English trials, 4 weeks of the diet did not change the intake of most nutrients compared with control diets, but lowered scores for overall diet quality compared with continuing the usual diet (Staudacher et al., 2020). In a U.S. trial in people with diarrhea-predominant irritable bowel syndrome, several vitamins and minerals fell on the diet, but after accounting for the lower total food intake only riboflavin remained lower; fewer people met recommended intakes for thiamin and iron (Eswaran et al., 2020). A third trial found lower blood levels of calcium and of ferritin, a measure of iron stores, after the diet (Roth et al., 2026).

These findings are for weeks of restriction under a dietitian's guidance. The concern guidelines raise is longer restriction without that guidance. The American College of Gastroenterology notes that long-term over-restriction of FODMAPs may lead to micronutrient deficiencies (Lacy et al., 2021).

Cardiometabolic outcomes

The searches for this page found no trial of cardiovascular events. An irritable bowel syndrome trial that randomized 155 people to the low-FODMAP diet or a starch- and sucrose-reduced diet also studied blood lipids and other metabolic and nutritional markers: in the low-FODMAP group, total cholesterol and LDL cholesterol were slightly lower after 4 weeks than at the start, but not at 6 months (Roth et al., 2026). Those are changes within one group, not a comparison with usual eating, and they do not establish cardiovascular disease prevention.

Cancer

The searches for this page found no trial of the diet's effect on cancer incidence, progression or survival. Small studies during cancer treatment have addressed gastrointestinal symptoms and treatment tolerance, which are different outcomes. In one, 26 women receiving pelvic radiotherapy for gynecological tumors were randomized to a low-FODMAP diet or a standard Mexican diet, and the trial measured gastrointestinal toxicity, symptoms and quality of life (Soto-Lugo et al., 2017). The studies reviewed here do not establish any effect on cancer itself in either direction.

Body weight, as measured

Body weight was not a main outcome of the symptom trials, and the Monash team states that the diet is not intended as a weight-loss plan (Monash University, n.d.-a). Where weight was measured, it usually fell a little, probably because people ate less overall. In the trial above that measured blood lipids, weight fell by about 0.8 kg on the diet, less than on the starch- and sucrose-reduced diet (Roth et al., 2026), and in the U.S. trial people on the diet ate fewer calories (Eswaran et al., 2020).

For some people the loss was larger. In the German clinic study, 12 of the 33 patients who completed 8 weeks developed what the authors called significant weight loss (Frieling et al., 2019). Weight a person loses without meaning to is a reason to involve a clinician, and it is one of the warning signs that call for medical investigation in irritable bowel syndrome (Lacy et al., 2021). It is never a sign that the diet is working.

Mortality

The searches for this page found no trial or cohort study of the diet's effect on death from any cause. The trials were short and measured symptoms, and nothing in the studies reviewed here establishes an effect on survival in either direction.

Eating behavior and wellbeing

The trials measured quality of life less consistently than symptoms. The American College of Gastroenterology reports that one trial found no significant improvement in general quality of life and another an improvement in quality of life specific to irritable bowel syndrome (Lacy et al., 2021). In an Australian trial, 74 adults were randomized to gut-directed hypnotherapy, the low-FODMAP diet or both for 6 weeks; all 3 groups improved similarly in gut symptoms and quality of life, but anxiety and depression scores improved more with hypnotherapy than with the diet (Peters et al., 2016).

Food-related quality of life, which measures the strain of planning, buying and eating food, is where the diet's costs show. People still following strict restriction years later reported lower food-related quality of life than those on a personalized or usual diet (Silva et al., 2025). The evidence on disordered eating is described under special populations in section 3 and in section 6.

Evidence from long-term prospective cohort studies

The searches for this page found no long-term prospective cohort study of the diet's effect on cardiovascular disease, cancer, body weight or death. The diet is a short treatment for a symptom condition, not a long-term pattern that large cohorts have tracked. What exists instead are follow-up studies of patients after they were taught the diet. These follow people forward, or ask them about their experience years later, without a comparison group, so they can describe what happened but cannot show that the diet caused it.

Symptom control after reintroduction

In 103 English patients followed after dietitian teaching, 12 percent reported satisfactory relief of symptoms before the diet, 61 percent after restriction, and 57 percent at the longer follow-up after reintroduction; 82 percent were still limiting some FODMAPs, and nutrient intake was judged adequate in both those who did and those who did not (O'Keeffe et al., 2018). In 74 Australian patients interviewed a mean of 7.1 years after being taught the diet, 64 percent reported satisfactory relief, and when symptoms flared, 66 percent adjusted their FODMAP intake (Silva et al., 2025). In 18 patients seen at 12 months, 67 percent reported adequate relief compared with 28 percent before the diet (Staudacher et al., 2022).

A 2025 meta-analysis pooled 5 studies with 324 patients who followed the diet for at least 6 months and reported less severe gut symptoms, less anxiety and depression and better quality of life, but no change in sleep quality (Pouladi et al., 2025). The abstract this page read does not describe the designs of the included studies, so the pooled numbers are not used here. All of these studies share a weakness: people who did well on the diet may have been more likely to take part.

Cardiometabolic outcomes, cancer, body weight and mortality

None was found, as the opening of this subsection says. The trial findings on these outcomes are earlier in this section.

Highlighted studies

These 4 trials carry the most weight for understanding the diet: the early feeding trial, the first comparison with ordinary advice, the first sham-controlled trial, and the largest trial to compare the diet with medication. All 4 were read in full. The early feeding trial and the comparison with ordinary advice were read as published articles, and the sham-controlled trial as the authors' accepted manuscript. CARIBS was read as a copy of the published article held in the University of Gothenburg's thesis repository, together with its published correction, which changed only the spelling of the trial's name in the title.

On a narrow screen, scroll the table sideways to see every column.

Highlighted studies for the Low-FODMAP Diet

Study	Design	Sample size	Duration	Finding	The limitation that matters
Halmos et al., 2014	Randomized crossover trial with almost all food supplied, single-blind	30 adults with irritable bowel syndrome and 8 healthy controls	21 days on each diet, with at least 21 days between	Overall symptom score 22.8 on the low-FODMAP diet against 44.9 on a typical Australian diet, on a 100 mm scale. Bloating, pain and wind were also lower.	Very small, short, and with all food supplied; it shows what the diet can do under ideal conditions, not what happens when people follow it on their own.
Böhn et al., 2015	Randomized trial against traditional dietary advice for irritable bowel syndrome, single-blind	75 adults randomized; 67 completed	4 weeks	Symptoms improved in both groups with no significant difference between them: 50 percent (19 of 38) on the low-FODMAP diet and 46 percent (17 of 37) on traditional advice improved by 50 points or more on the severity scale.	Too small to detect a modest difference, so it did not demonstrate that the 2 approaches are equal either.
Staudacher et al., 2017	Randomized 2 by 2 trial against a sham diet, with a probiotic or placebo	104 adults	4 weeks	Adequate relief in 57 percent on the low-FODMAP diet against 38 percent on the sham diet (P = .051 in the main analysis); symptom severity clearly lower; Bifidobacteria lower on the diet.	The main relief result fell just short of statistical significance, and the trial could not say which FODMAP mattered most.
Nybacka et al., 2024, CARIBS	Randomized trial of 2 diets against optimized medication, single-blind for the diets	304 adults with moderate to severe irritable bowel syndrome randomized; the 294 who started treatment were analyzed	4 weeks of randomized comparison. Follow-up ran to 6 months, but after the first 4 weeks the diets were revealed to participants and the medication group was offered dietary advice.	Response at 4 weeks, meaning a fall of at least 50 points on a 500-point symptom-severity score: 76 percent (73 of 96) on low-FODMAP plus traditional advice, 71 percent (69 of 97) on a low-carbohydrate diet and 58 percent (59 of 101) on medication chosen for the main symptom.	One specialist center, and the medication arm was open-label; the diet tested combined low-FODMAP and traditional advice, so it is not the low-FODMAP diet alone.

Head to head

In the trials summarized here, low-FODMAP restriction did not consistently outperform traditional dietary advice for irritable bowel syndrome. In Sweden, 50 percent improved on the low-FODMAP diet and 46 percent on traditional advice (Böhn et al., 2015). In the United States, adequate relief was reported by 52 percent and 41 percent, not a significant difference, although abdominal pain responded better on the low-FODMAP diet, 51 percent against 23 percent (Eswaran et al., 2016).

The published abstract reports that traditional dietary advice itself performed better than usual eating. It does not report the overall-symptom estimate comparing low-FODMAP with traditional advice, so that estimate remains provisional and is withheld pending examination of the published main article. The separately examined published appendix rates the direct evidence for that comparison Low on the CINeMA scale (Cuffe et al., 2025).

Against a gluten-free diet, an English trial in people without constipation found response rates of 42 percent for traditional advice, 55 percent for the low-FODMAP diet and 58 percent for a gluten-free diet, with no significant difference; people found traditional advice cheaper and easier, and the authors recommended it as the first dietary choice (Rej et al., 2022). The gluten-free diet has its own page in this archive: Gluten-Free Diet.

Against medication, 2 trials favored diet. In CARIBS, described in the table, response was more frequent with low-FODMAP plus traditional advice than with optimized medication. The low-carbohydrate group's response rate was also higher than the medication group's, but that difference was uncertain, because it fell short of statistical significance, and response did not clearly differ between the 2 diets. Both diets produced larger falls in symptom-severity scores than medication (Nybacka et al., 2024). In a Belgian primary care trial of 459 patients, a smartphone app teaching a FODMAP-lowering diet produced more responders at 8 weeks than the antispasmodic medicine otilonium bromide, 71 percent against 61 percent (Carbone et al., 2022). Against gut-directed hypnotherapy, a psychological treatment, an Australian trial found gut symptoms improved about equally, with no added benefit from combining them (Peters et al., 2016).

The published appendix lists 2 trials of a starch- and sucrose-reduced diet and 1 trial each of gluten-free and tritordeum-based diets (Cuffe et al., 2025). These remain small bodies of evidence. These trial counts do not establish which diet is best. The unverified comparisons and proposed overlap in FODMAP restriction are withheld while the published main article remains unavailable.

Where the evidence is absent

The searches for this page found no trial of the diet's effect on cardiovascular events, on cancer incidence, progression or survival, or on death, and no long-term cohort study of these outcomes in people following it. They found no trial during pregnancy. A small trial tested a low-FODMAP diet in breastfeeding mothers for infant colic, rather than maternal irritable bowel syndrome or the long-term safety of restriction (Iacovou et al., 2018).

Trials in children are few and small; a pilot trial in 27 children with functional abdominal pain found no significant improvement on the diet (Boradyn et al., 2020), and the 2025 pediatric guideline found no benefit conclusion that reached even low certainty (Groen et al., 2025). The evidence in older adults is a single study of 20 people without a comparison group (O'Brien et al., 2020), and the evidence in athletes is a handful of trials lasting about a week.

The 2025 review's detailed findings on reintroduction, trial settings, constipation-predominant disease and harms remain provisional pending examination of its published main article. Those unreconciled details are not used here to draw conclusions (Cuffe et al., 2025). The effect of following the diet without a dietitian, from an app or a list, has been tested in few trials. Restriction lowers fecal Bifidobacteria over about 3 to 4 weeks. Whether this reduction persists during prolonged restriction, or affects health, is uncertain.

5. Mechanisms

(optional reading; select the heading to open or close this section)

This section explains how the diet is thought to work in the body. You can skip it. Nothing in the coaching sections depends on it.

Established mechanisms

FODMAPs act in 2 places, and both have been shown directly in people with magnetic resonance imaging of the gut. The small ones, such as fructose, draw water into the small intestine by osmosis: in 16 healthy volunteers, a drink containing 40 grams of fructose roughly doubled the water in the small bowel over 5 hours compared with glucose. The larger ones, such as the fructan inulin, pass through to the colon, where bacteria ferment them and produce gas: inulin increased gas in the colon more than fructose did, while causing few symptoms in those healthy volunteers (Murray et al., 2014).

Why people with irritable bowel syndrome feel this more than other people was tested in a follow-up trial. In 29 adults with irritable bowel syndrome and 29 healthy controls, fructose and inulin produced similar amounts of water, gas and breath hydrogen in both groups, but more of the people with irritable bowel syndrome developed symptoms, and in those who reacted to inulin, the intensity of symptoms tracked the amount of gas in the colon (Major et al., 2017). The authors concluded that a gut that is more sensitive to being stretched, rather than one that makes more gas, explains the symptoms. The diet works, in this account, by reducing the stretching that a sensitive gut experiences as pain and bloating.

Proposed mechanisms

Some researchers propose that a person's gut bacteria predict whether the diet will work. In the pediatric trial described in section 3, children who responded had more of certain carbohydrate-fermenting bacteria at the start (Chumpitazi et al., 2015). The American Gastroenterological Association states that there are limited data on such biomarkers and not enough evidence to use them in routine practice (Chey et al., 2022). That the drop in Bifidobacteria during restriction could affect long-term health is also a proposal, resting on animal studies rather than evidence in people (So et al., 2022). A proposed mechanism never supports a claim in section 4.

6. Risks, contraindications and myths

(select the heading to open or close this section)

Warnings from professional or regulatory bodies

The searches for this page found no regulatory warning about the diet itself. The professional bodies that recommend it attach conditions to its use, and those conditions are the warnings. The American Gastroenterological Association states that "patients with IBS who are poor candidates for restrictive diet interventions include those consuming few culprit foods, those at risk for malnutrition, those who are food insecure, and those with an eating disorder or uncontrolled psychiatric disorder," and that "routine screening for disordered eating or eating disorders by careful dietary history is critical" (Chey et al., 2022).

England's National Institute for Health and Care Excellence recommends that further dietary management, including a low-FODMAP diet, should "only be given by a healthcare professional with expertise in dietary management" (National Institute for Health and Care Excellence, 2017). The British Society of Gastroenterology recommends the diet as a second-line dietary therapy whose implementation should be supervised by a trained dietitian, with FODMAPs reintroduced according to tolerance; the guideline grades this a weak recommendation based on very low quality evidence (Vasant et al., 2021). For children, the 2025 European and North American guideline warns that restrictive diets "should be employed with the same consideration as all active interventions, with particular caution in children with risk factors for disordered eating" (Groen et al., 2025). And the program's developer states that if a doctor has not diagnosed a person's gut symptoms, "you should not be following this diet" (Monash University, n.d.-a).

Nutrient gaps

The diet cuts many foods that supply fiber, such as wheat, rye, beans, lentils and several fruits and vegetables, and dairy foods that supply calcium. A Monash research dietitian writes that the strict diet can compromise intake of fiber, calcium and B vitamins, which is one reason the team advises against following it for life (Varney, 2015b). The short trials described in section 4 found modest changes under a dietitian's guidance. Fiber deserves particular attention because many people with irritable bowel syndrome already eat little of it: in one English sample, only 5 percent met the 30 grams a day target before any diet began (Staudacher et al., 2020). Whether a particular version of the diet meets a person's needs, and how to replace what is cut, are questions for a registered dietitian. The searches for this page found no current authority that sets nutrient numbers specific to this diet.

Who should not follow it without medical supervision

Anyone whose gut symptoms have not been diagnosed by a clinician, or who has warning signs such as blood in the stool or weight loss they did not intend, because other conditions cause similar symptoms and need their own care (Lacy et al., 2021; Monash University, n.d.-a). Monash advises being properly assessed for celiac disease before removing gluten entirely from the diet (Monash University, n.d.-b). Anyone with a current or past eating disorder, at risk of malnutrition, or short of food (Chey et al., 2022). Children and adolescents (Groen et al., 2025), people who are pregnant (Iacovou, 2016), and older adults or anyone already following other dietary restrictions, for whom Monash dietitians suggest a gentler version (Collins & Halmos, 2020). And anyone taking insulin or another diabetes medicine that can lower blood sugar, who keeps the prescriber informed before a substantial change in eating.

Medication interactions

A coach never adjusts medication. The point of knowing these is to know when to send a client back to the prescriber. The searches for this page found no medication whose dose is known to need changing because of this diet itself. The practical issue is indirect: in a U.S. trial, people on the diet ate fewer calories, fewer meals and less carbohydrate (Eswaran et al., 2020), which can matter for someone whose diabetes medicine lowers blood sugar. A client on insulin, a sulfonylurea, blood pressure medication or warfarin who plans a substantial change in eating keeps the prescriber informed before making it.

Medication for irritable bowel syndrome is a separate decision for the client and their clinician. A client who wants to stop a medicine because of the diet takes that to the prescriber.

Signs it is going wrong

Physical signs a coach or a family member might notice are weight loss the person did not intend, tiredness, constipation that worsens, symptoms that do not improve after the planned weeks of restriction, and any of the warning signs listed above, such as blood in the stool. The American Gastroenterological Association advises that a diet that brings no clinical response within a set time should be abandoned for another treatment (Chey et al., 2022). Each of these is a reason to involve a clinician, not a diagnosis; the coach notices, encourages the client to tell their clinician, and leaves the cause to the clinician.

Behavior matters as much and needs care, because restricting foods is the point of the first step. What carries more meaning is restriction that outlasts its plan: staying strict for months, skipping reintroduction, adding more foods to the avoid list, adding other diets on top of this one, anxiety about eating, or turning down meals with other people. In studies of avoidant/restrictive food intake disorder in people with gut disorders, fear of consequences such as pain, nausea or vomiting was the most prominent feature (Henriksen et al., 2026). The questions are the same in every case: what the behavior is for, whether it causes distress, whether it is narrowing what the person eats, and whether it is getting in the way of daily life. Where the answers raise a real concern about disordered eating, the coach follows their own referral process.

Myths and where they came from

Myth: low-FODMAP is a healthy way for anyone to eat

Where it came from: the diet's popularity, lists shared online, and the general idea that cutting foods is healthy. What is true: it was developed and tested as a treatment for the symptoms of diagnosed irritable bowel syndrome. Monash states that most people eat high-FODMAP foods every day without issue (Monash University, n.d.-a), and in people with irritable bowel syndrome the strict diet lowered diet quality scores and the abundance of Bifidobacteria (So et al., 2022; Staudacher et al., 2020). These studies do not establish a general health benefit for people without relevant symptoms or a clinical indication. Small studies in other symptomatic populations address separate questions, as described in section 2.

Myth: the diet heals the gut or cures irritable bowel syndrome

Where it came from: enthusiastic descriptions, including the developer's own FAQ, which says the aim of the diet "is to heal your gut" (Monash University, n.d.-b). What is true: the same organization states on its main page that the diet "does not cure IBS symptoms, it just helps people to live more comfortably with their condition" (Monash University, n.d.-a). The trials measured symptom relief, and symptoms return when FODMAPs that a person does not tolerate come back.

Myth: the stricter and longer, the better

Where it came from: the relief people feel in the first weeks, and food lists that show the restriction step without the steps that follow. What is true: the developers advise 2 to 6 weeks of restriction followed by reintroduction, and warn against following the strict diet for life because of its effects on fiber and nutrient intake, gut bacteria and social life (Varney, 2015b). People who stayed strict for years reported lower food-related quality of life without better symptom control (Silva et al., 2025).

Myth: a food sensitivity test can tell me which foods to cut

Where it came from: tests sold directly to consumers that claim to identify food intolerances from a blood sample. What is true: the American College of Gastroenterology states that none of these tests has been validated and that serum IgG panels cannot be recommended (Lacy et al., 2021). The reintroduction step, done with a dietitian, is how the diet identifies an individual's triggers.

Myth: low-FODMAP means gluten-free

Where it came from: wheat, rye and barley are cut back in the first step, and many gluten-free products happen to be low in FODMAPs. What is true: the diet limits the fructans in these grains, not the gluten protein. Spelt is a form of wheat. Traditionally fermented spelt sourdough contains gluten but can be low in FODMAPs in the servings Monash tested, because the long fermentation breaks down FODMAPs. Spelt bread made by modern methods had much higher FODMAP levels, and Monash rated spelt pasta at a typical serving and spelt flakes high, so not every spelt product is low in FODMAPs (Collins, 2017; Muir, 2015). Monash also notes that choosing a strict gluten-free diet when only a low-FODMAP diet is needed can lead to over-restriction. Gluten-free and low-FODMAP describe different properties of food. A strict, lifelong gluten-free diet is for people diagnosed with celiac disease (Monash University, n.d.-b).

7. Key terms

FODMAPs

Fermentable oligosaccharides, disaccharides, monosaccharides and polyols: short-chain carbohydrates that are poorly absorbed in the small intestine and are fermented by bacteria in the colon.

Irritable bowel syndrome

A common disorder of gut-brain interaction marked by recurring abdominal pain linked to bowel movements and changes in how often or how firm they are. It is diagnosed by a clinician.

Fructans and galacto-oligosaccharides

Chains of sugar units found in wheat, rye, onion and garlic (fructans) and in beans and lentils (galacto-oligosaccharides). No one fully digests them, so they reach the colon.

Polyols

Sugar alcohols such as sorbitol and mannitol, found in some fruit and vegetables and used as sweeteners.

Restriction step

The first step of the diet, lasting about 2 to 6 weeks, in which high-FODMAP foods are swapped for low-FODMAP ones.

Reintroduction

The second step, in which foods rich in one FODMAP group are eaten for a few days at a time to see which groups a person tolerates. Also called challenges.

Personalization

The third step: a long-term diet that limits only the FODMAPs, and amounts, that a person found troublesome.

FODMAP-gentle diet

A milder version that limits only a few foods very high in FODMAPs, suggested for people for whom the full diet is too restrictive or too risky.

Sham diet

A comparison diet in a trial that restricts a similar number of foods without targeting FODMAPs, so participants cannot easily tell which diet they are on.

Network meta-analysis

A review that combines trials comparing 2 treatments directly with trials that connect them indirectly through a shared comparison, so several treatments can be compared at once.

CINeMA

Confidence in Network Meta-Analysis, a framework for rating how much confidence to place in each comparison in a network meta-analysis. Its labels are not interchangeable with GRADE ratings for a single comparison.

Bifidobacteria

A group of gut bacteria that ferment carbohydrates such as fructans. Their numbers fall during strict FODMAP restriction.

Avoidant/restrictive food intake disorder

An eating disorder of restricted eating, often driven by fear of what eating will cause, without the distorted body image or wish to lose weight seen in anorexia nervosa.

8. Review questions

1. Name the 3 steps of the low-FODMAP diet and what each one is for. Then explain why a person who stays on the first step indefinitely is not following the diet as its developers designed it.
2. Using section 4, describe what the 2025 network meta-analysis compared and how large the overall-symptom effect was against usual eating. How does confidence in the direct evidence differ between usual eating and traditional dietary advice? Why does a confidence rating alone not tell you the size of a benefit?
3. A client tells you she has had bloating and diarrhea for 2 months, found a FODMAP list online and has cut out everything on it. She has lost some weight and is happy about it. What does the coach do, and where is the referral line? Name at least 2 reasons this diet needs a clinician first.
4. Pick one myth from section 6. Explain where it came from and what the evidence shows instead.

9. References

Aleksandrowicz, L., Green, R., Joy, E. J., Smith, P., & Haines, A. (2016). The impacts of dietary change on greenhouse gas emissions, land use, water use, and health: A systematic review. PLOS ONE, 11(11), Article e0165797. https://doi.org/10.1371/journal.pone.0165797

Böhn, L., Störsrud, S., Liljebo, T., Collin, L., Lindfors, P., Törnblom, H., & Simrén, M. (2015). Diet low in FODMAPs reduces symptoms of irritable bowel syndrome as well as traditional dietary advice: A randomized controlled trial. Gastroenterology, 149(6), 1399-1407.e2. https://doi.org/10.1053/j.gastro.2015.07.054

Boradyn, K. M., Przybyłowicz, K. E., & Jarocka-Cyrta, E. (2020). Low FODMAP diet is not effective in children with functional abdominal pain: A randomized controlled trial. Annals of Nutrition and Metabolism, 76(5), 334-344. https://doi.org/10.1159/000510795

Carbone, F., Van den Houte, K., Besard, L., Tack, C., Arts, J., Caenepeel, P., Piessevaux, H., Vandenberghe, A., Matthys, C., Biesiekierski, J., Capiau, L., Ceulemans, S., Gernay, O., Jones, L., Maes, S., Peetermans, C., Raat, W., Stubbe, J., Van Boxstael, R., . . . Tack, J. (2022). Diet or medication in primary care patients with IBS: The DOMINO study - a randomised trial supported by the Belgian Health Care Knowledge Centre (KCE Trials Programme) and the Rome Foundation Research Institute. Gut, 71(11), 2226-2232. https://doi.org/10.1136/gutjnl-2021-325821

Chey, W. D., Hashash, J. G., Manning, L., & Chang, L. (2022). AGA clinical practice update on the role of diet in irritable bowel syndrome: Expert review. Gastroenterology, 162(6), 1737-1745.e5. https://doi.org/10.1053/j.gastro.2021.12.248

Chumpitazi, B. P., Cope, J. L., Hollister, E. B., Tsai, C. M., McMeans, A. R., Luna, R. A., Versalovic, J., & Shulman, R. J. (2015). Randomised clinical trial: Gut microbiome biomarkers are associated with clinical response to a low FODMAP diet in children with the irritable bowel syndrome. Alimentary Pharmacology & Therapeutics, 42(4), 418-427. https://doi.org/10.1111/apt.13286

Collins, L. (2017, November 8). Sourdough processing & FODMAPs. Monash FODMAP. www.monashfodmap.com/blog/sourdough-processing-fodmaps/

Collins, L., & Halmos, E. (2020, February 24). A FODMAP gentle approach. Monash FODMAP. www.monashfodmap.com/blog/gentle-fodmap-diet/

Cox, S. R., Lindsay, J. O., Fromentin, S., Stagg, A. J., McCarthy, N. E., Galleron, N., Ibraim, S. B., Roume, H., Levenez, F., Pons, N., Maziers, N., Lomer, M. C., Ehrlich, S. D., Irving, P. M., & Whelan, K. (2020). Effects of low FODMAP diet on symptoms, fecal microbiome, and markers of inflammation in patients with quiescent inflammatory bowel disease in a randomized trial. Gastroenterology, 158(1), 176-188.e7. https://doi.org/10.1053/j.gastro.2019.09.024

Cuffe, M. S., Staudacher, H. M., Aziz, I., Coss Adame, E., Krieger-Grubel, C., Madrid, A. M., Ohlsson, B., Black, C. J., & Ford, A. C. (2025). Efficacy of dietary interventions in irritable bowel syndrome: A systematic review and network meta-analysis. The Lancet Gastroenterology & Hepatology, 10(6), 520-536. https://doi.org/10.1016/S2468-1253(25)00054-8

Dwyer, E. (2018, January 15). The 3 steps of the FODMAP diet. Monash FODMAP. www.monashfodmap.com/blog/3-phases-low-fodmap-diet/

Eswaran, S., Dolan, R. D., Ball, S. C., Jackson, K., & Chey, W. (2020). The impact of a 4-week low-FODMAP and mNICE diet on nutrient intake in a sample of US adults with irritable bowel syndrome with diarrhea. Journal of the Academy of Nutrition and Dietetics, 120(4), 641-649. https://doi.org/10.1016/j.jand.2019.03.003

Eswaran, S. L., Chey, W. D., Han-Markey, T., Ball, S., & Jackson, K. (2016). A randomized controlled trial comparing the low FODMAP diet vs. modified NICE guidelines in US adults with IBS-D. The American Journal of Gastroenterology, 111(12), 1824-1832. https://doi.org/10.1038/ajg.2016.434

Flack, R., Brownlow, G., Burton-Murray, H., Palsson, O., & Aziz, I. (2026). The prevalence and burden of avoidant/restrictive food intake disorder symptoms in adults with disorders of gut-brain interaction: A population-based study. Gastroenterology, 170(2), 365-374. https://doi.org/10.1053/j.gastro.2025.07.043

Frieling, T., Heise, J., Krummen, B., Hundorf, C., & Kalde, S. (2019). Tolerability of FODMAP - reduced diet in irritable bowel syndrome - efficacy, adherence, and body weight course. Zeitschrift für Gastroenterologie, 57(6), 740-744. https://doi.org/10.1055/a-0859-7531

Gibson, P. R., & Shepherd, S. J. (2005). Personal view: Food for thought--western lifestyle and susceptibility to Crohn's disease. The FODMAP hypothesis. Alimentary Pharmacology & Therapeutics, 21(12), 1399-1409. https://doi.org/10.1111/j.1365-2036.2005.02506.x

Groen, J., Gordon, M., Chogle, A., Benninga, M., Borlack, R., Borrelli, O., Darbari, A., Dolinsek, J., Khlevner, J., Di Lorenzo, C., Person, H., Sanghavi, R., Snyder, J., Thapar, N., Vlieger, A., Sinopoulou, V., Tabbers, M., & Saps, M. (2025). ESPGHAN/NASPGHAN guidelines for treatment of irritable bowel syndrome and functional abdominal pain-not otherwise specified in children aged 4-18 years. Journal of Pediatric Gastroenterology and Nutrition, 81(2), 442-471. https://doi.org/10.1002/jpn3.70070

Halmos, E. P., & Gibson, P. R. (2019). Controversies and reality of the FODMAP diet for patients with irritable bowel syndrome. Journal of Gastroenterology and Hepatology, 34(7), 1134-1142. https://doi.org/10.1111/jgh.14650

Halmos, E. P., Power, V. A., Shepherd, S. J., Gibson, P. R., & Muir, J. G. (2014). A diet low in FODMAPs reduces symptoms of irritable bowel syndrome. Gastroenterology, 146(1), 67-75.e5. https://doi.org/10.1053/j.gastro.2013.09.046

Henriksen, S. B., Hornemann, C., & Hulgaard, D. R. (2026). Avoidant-restrictive food intake disorder in patients with gastrointestinal disorders: A systematic review. Journal of Human Nutrition and Dietetics, 39(2), Article e70226. https://doi.org/10.1111/jhn.70226

Iacovou, M. (2016, May 19). The low FODMAP diet during pregnancy. Monash FODMAP. www.monashfodmap.com/blog/the-low-fodmap-diet-during-pregnancy/

Iacovou, M., Craig, S. S., Yelland, G. W., Barrett, J. S., Gibson, P. R., & Muir, J. G. (2018). Randomised clinical trial: Reducing the intake of dietary FODMAPs of breastfeeding mothers is associated with a greater improvement of the symptoms of infantile colic than for a typical diet. Alimentary Pharmacology & Therapeutics, 48(10), 1061-1073. https://doi.org/10.1111/apt.15007

Lacy, B. E., Pimentel, M., Brenner, D. M., Chey, W. D., Keefer, L. A., Long, M. D., & Moshiree, B. (2021). ACG clinical guideline: Management of irritable bowel syndrome. The American Journal of Gastroenterology, 116(1), 17-44. https://doi.org/10.14309/ajg.0000000000001036

Lis, D. M., Stellingwerff, T., Kitic, C. M., Fell, J. W., & Ahuja, K. D. K. (2018). Low FODMAP: A preliminary strategy to reduce gastrointestinal distress in athletes. Medicine & Science in Sports & Exercise, 50(1), 116-123. https://doi.org/10.1249/MSS.0000000000001419

Major, G., Pritchard, S., Murray, K., Alappadan, J. P., Hoad, C. L., Marciani, L., Gowland, P., & Spiller, R. (2017). Colon hypersensitivity to distension, rather than excessive gas production, produces carbohydrate-related symptoms in individuals with irritable bowel syndrome. Gastroenterology, 152(1), 124-133.e2. https://doi.org/10.1053/j.gastro.2016.09.062

Monash University. (n.d.-a). About FODMAPs and IBS. Monash FODMAP. www.monashfodmap.com/about-fodmap-and-ibs/

Monash University. (n.d.-b). FODMAP FAQs. Monash FODMAP. www.monashfodmap.com/about-fodmap-and-ibs/frequently-asked-questions/

Monash University. (n.d.-c). Join the Monash University Low FODMAP Certification program. Monash FODMAP. www.monashfodmap.com/product-and-recipe-certification-program/about-certification/

Monash University. (n.d.-d). Low FODMAP diet app help. Monash FODMAP. www.monashfodmap.com/get-app-help/

Monash University. (n.d.-e). Research at Monash University. Monash FODMAP. www.monashfodmap.com/about-fodmap-and-ibs/research-monash-university/

Monash University. (n.d.-f). Starting the low FODMAP diet. Monash FODMAP. www.monashfodmap.com/ibs-central/i-have-ibs/starting-the-low-fodmap-diet/

Monash University. (n.d.-g). Take online FODMAP training: Patients course. Monash FODMAP. www.monashfodmap.com/online-training/patients-course/

Muir, J. (2015, April 1). Spelt products and FODMAPs. Monash FODMAP. www.monashfodmap.com/blog/are-all-spelt-products-low-in-fodmaps/

Murray, K., Wilkinson-Smith, V., Hoad, C., Costigan, C., Cox, E., Lam, C., Marciani, L., Gowland, P., & Spiller, R. C. (2014). Differential effects of FODMAPs (fermentable oligo-, di-, mono-saccharides and polyols) on small and large intestinal contents in healthy subjects shown by MRI. The American Journal of Gastroenterology, 109(1), 110-119. https://doi.org/10.1038/ajg.2013.386

National Institute for Health and Care Excellence. (2017). Irritable bowel syndrome in adults: Diagnosis and management (Clinical guideline CG61). www.nice.org.uk/guidance/cg61/chapter/Recommendations

Nikolakopoulou, A., Higgins, J. P. T., Papakonstantinou, T., Chaimani, A., Del Giovane, C., Egger, M., & Salanti, G. (2020). CINeMA: An approach for assessing confidence in the results of a network meta-analysis. PLOS Medicine, 17(4), Article e1003082. https://doi.org/10.1371/journal.pmed.1003082

Nybacka, S., Törnblom, H., Josefsson, A., Hreinsson, J. P., Böhn, L., Frändemark, Å., Weznaver, C., Störsrud, S., & Simrén, M. (2024). A low FODMAP diet plus traditional dietary advice versus a low-carbohydrate diet versus pharmacological treatment in irritable bowel syndrome (CARIBS): A single-centre, single-blind, randomised controlled trial. The Lancet Gastroenterology & Hepatology, 9(6), 507-520. https://doi.org/10.1016/S2468-1253(24)00045-1

O'Brien, L., Skidmore, P., Wall, C., Wilkinson, T., Muir, J., Frampton, C., & Gearry, R. (2020). A low FODMAP diet is nutritionally adequate and therapeutically efficacious in community dwelling older adults with chronic diarrhoea. Nutrients, 12(10), Article 3002. https://doi.org/10.3390/nu12103002

O'Keeffe, M., Jansen, C., Martin, L., Williams, M., Seamark, L., Staudacher, H. M., Irving, P. M., Whelan, K., & Lomer, M. C. (2018). Long-term impact of the low-FODMAP diet on gastrointestinal symptoms, dietary intake, patient acceptability, and healthcare utilization in irritable bowel syndrome. Neurogastroenterology & Motility, 30(1), Article e13154. https://doi.org/10.1111/nmo.13154

Peters, S. L., Yao, C. K., Philpott, H., Yelland, G. W., Muir, J. G., & Gibson, P. R. (2016). Randomised clinical trial: The efficacy of gut-directed hypnotherapy is similar to that of the low FODMAP diet for the treatment of irritable bowel syndrome. Alimentary Pharmacology & Therapeutics, 44(5), 447-459. https://doi.org/10.1111/apt.13706

Pouladi, A., Arabpour, E., Bahrami, O., Sadeghi, A., Mozafari Komesh Tape, P., Abdehagh, M., & Zali, M. R. (2025). 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, 38(4), Article e70105. https://doi.org/10.1111/jhn.70105

Rej, A., Sanders, D. S., Shaw, C. C., Buckle, R., Trott, N., Agrawal, A., & Aziz, I. (2022). Efficacy and acceptability of dietary therapies in non-constipated irritable bowel syndrome: A randomized trial of traditional dietary advice, the low FODMAP diet, and the gluten-free diet. Clinical Gastroenterology and Hepatology, 20(12), 2876-2887.e15. https://doi.org/10.1016/j.cgh.2022.02.045

Roth, B., D'Amato, M., & Ohlsson, B. (2026). Improved lipid and glycemic profile and vitamin D levels after a dietary intervention with SSRD and low FODMAP in IBS patients: A randomized controlled trial. Nutrition, 142, Article 112964. https://doi.org/10.1016/j.nut.2025.112964

Shepherd, S. J., & Gibson, P. R. (2006). Fructose malabsorption and symptoms of irritable bowel syndrome: Guidelines for effective dietary management. Journal of the American Dietetic Association, 106(10), 1631-1639. https://doi.org/10.1016/j.jada.2006.07.010

Shepherd, S. J., Parker, F. C., Muir, J. G., & Gibson, P. R. (2008). Dietary triggers of abdominal symptoms in patients with irritable bowel syndrome: Randomized placebo-controlled evidence. Clinical Gastroenterology and Hepatology, 6(7), 765-771. https://doi.org/10.1016/j.cgh.2008.02.058

Silva, H., Knowles, S. R., Porter, J., Barrett, J., Gibson, P. R., & Garg, M. (2026). Disordered eating behaviors many years after education in a low FODMAP diet in patients with irritable bowel syndrome. JGH Open, 10(9), Article e70467. https://doi.org/10.1002/jgh3.70467

Silva, H., Porter, J., Barrett, J., Gibson, P. R., & Garg, M. (2025). Dietary intake, symptom control and quality of life after dietitian-delivered education on a FODMAP diet for irritable bowel syndrome: A 7-year follow up. Neurogastroenterology & Motility, 37(12), Article e70116. https://doi.org/10.1111/nmo.70116

So, D., Loughman, A., & Staudacher, H. M. (2022). 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, 116(4), 943-952. https://doi.org/10.1093/ajcn/nqac176

Soto-Lugo, J. H., Souto-Del Bosque, M. Á., & Vázquez-Martínez, C. A. (2017). Effectiveness of nutritional intervention in reduction of gastrointestinal toxicity during external beam radiotherapy in women with gynecological tumors. Gaceta Mexicana de Oncología, 16(2), 84-90. https://doi.org/10.24875/j.gamo.17000016

Staudacher, H. M., Lomer, M. C. E., Farquharson, F. M., Louis, P., Fava, F., Franciosi, E., Scholz, M., Tuohy, K. M., Lindsay, J. O., Irving, P. M., & Whelan, K. (2017). A diet low in FODMAPs reduces symptoms in patients with irritable bowel syndrome and a probiotic restores Bifidobacterium species: A randomized controlled trial. Gastroenterology, 153(4), 936-947. https://doi.org/10.1053/j.gastro.2017.06.010

Staudacher, H. M., Ralph, F. S. E., Irving, P. M., Whelan, K., & Lomer, M. C. E. (2020). 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, 120(4), 535-547. https://doi.org/10.1016/j.jand.2019.01.017

Staudacher, H. M., Rossi, M., Kaminski, T., Dimidi, E., Ralph, F. S. E., Wilson, B., Martin, L. D., Louis, P., Lomer, M. C. E., Irving, P. M., & Whelan, K. (2022). Long-term personalized low FODMAP diet improves symptoms and maintains luminal Bifidobacteria abundance in irritable bowel syndrome. Neurogastroenterology & Motility, 34(4), Article e14241. https://doi.org/10.1111/nmo.14241

Varney, J. (2015a, April 17). Low FODMAP diet on a budget. Monash FODMAP. www.monashfodmap.com/blog/low-fodmap-diet-on-budget/

Varney, J. (2015b, April 27). The Monash University Low FODMAP Diet: NOT a 'lifetime' diet. Monash FODMAP. www.monashfodmap.com/blog/low-fodmap-diet-not-lifetime-diet/

Varney, J. (2015c, May 8). The low FODMAP diet and diabetes management. Monash FODMAP. www.monashfodmap.com/blog/the-low-fodmap-diet-and-diabetes/

Vasant, D. H., Paine, P. A., Black, C. J., Houghton, L. A., Everitt, H. A., Corsetti, M., Agrawal, A., Aziz, I., Farmer, A. D., Eugenicos, M. P., Moss-Morris, R., Yiannakou, Y., & Ford, A. C. (2021). British Society of Gastroenterology guidelines on the management of irritable bowel syndrome. Gut, 70(7), 1214-1240. https://doi.org/10.1136/gutjnl-2021-324598

Watrowski, R., Kostov, S., Schäfer, S. D., Juhasz-Böss, I., Palumbo, M., Sparić, R., Mereu, L., Vitale, S. G., & Alkatout, I. (2026). Low-FODMAP diet for gastrointestinal symptoms in endometriosis: A systematic review. Nutrients, 18(13), Article 2164. https://doi.org/10.3390/nu18132164

Whigham, L., Joyce, T., Harper, G., Irving, P. M., Staudacher, H. M., Whelan, K., & Lomer, M. C. (2015). Clinical effectiveness and economic costs of group versus one-to-one education for short-chain fermentable carbohydrate restriction (low FODMAP diet) in the management of irritable bowel syndrome. Journal of Human Nutrition and Dietetics, 28(6), 687-696. https://doi.org/10.1111/jhn.12318

Wiffin, M., Smith, L., Antonio, J., Johnstone, J., Beasley, L., & Roberts, J. (2019). Effect of a short-term low fermentable oligiosaccharide, disaccharide, monosaccharide and polyol (FODMAP) diet on exercise-related gastrointestinal symptoms. Journal of the International Society of Sports Nutrition, 16(1), Article 1. https://doi.org/10.1186/s12970-019-0268-9

Evidence rating and review record

Each row identifies the method, source, outcome or recommendation, and comparison being rated. Ratings from different tools are not interchangeable. The source is either a named published review or this page's own judgment. The rating in the banner is for this diet's main claimed outcome or recommendation, and the banner names the tool that produced it. A high rating means the research is solid; it does not mean the diet is right for everyone, and it does not mean a coach should recommend it.

Rows rated with GRADE use the same 4-level scale as the clinical guidelines you will meet in practice. High means further research is very unlikely to change the conclusion. Moderate means further research may change it. Low means further research is likely to change it. Very low means the conclusion is uncertain. GRADE rates each outcome separately, so a diet can be high for one outcome and very low for another.

The banner row and row 3 carry the review authors' published CINeMA ratings. CINeMA is a framework for rating confidence in the results of a network meta-analysis (Nikolakopoulou et al., 2020). It uses the same 4 labels, but it rates one comparison in the network at a time, judging within-study bias, reporting bias, indirectness, imprecision, heterogeneity and incoherence, as the review's appendix shows (Cuffe et al., 2025). A CINeMA label is not interchangeable with a GRADE rating. Every row is about symptoms or a laboratory measure in people with a diagnosed condition, not about disease prevention or about people without the condition. Ratings marked as this page's own judgment were assigned from the evidence given in each row's reasons; ratings from a published review are reported exactly as that review published them.

On a narrow screen, scroll the table sideways to see every column.

Evidence ratings, their sources and reasons

Outcome	Certainty	Who rated it, and for which comparison	Why it is rated this way
Overall irritable bowel syndrome symptoms, short term, low-FODMAP diet against usual eating (the banner outcome)	Moderate, on the CINeMA scale	Cuffe et al., 2025, published Supplementary Table 5, using CINeMA. Adults with irritable bowel syndrome; low-FODMAP compared with usual eating. The label is for the direct trial evidence on this comparison.	The review's network estimate, which also draws on indirect comparisons, is a relative risk of symptoms not improving of 0.51, from 0.37 to 0.70, across 24 trials. The published appendix rates the direct habitual-diet comparison, 5 trials, Moderate, downgrading for within-study bias; it records some concerns about reporting bias without an additional downgrade, and no concerns for indirectness, imprecision, heterogeneity or incoherence. CINeMA is broadly based on GRADE and uses its 4 levels, with some differences in method (Nikolakopoulou et al., 2020).
Overall symptoms, low-FODMAP diet against a mix of comparison diets	Very low	Lacy et al., 2021, the American College of Gastroenterology guideline, using GRADE. A meta-analysis of 7 trials with 397 adults, against usual diet, other diets and a high-FODMAP diet.	Relative risk of symptoms not improving 0.69, from 0.54 to 0.88. The guideline judged all the trials at high risk of bias. Its recommendation for a limited trial of the diet is conditional. This is an older and smaller evidence base than the row above, rated by a different group; the 2 ratings are not interchangeable.
Overall symptoms, low-FODMAP diet against traditional dietary advice for irritable bowel syndrome	Low, on the CINeMA scale, for direct evidence; this page's GRADE judgment withheld	Published CINeMA assessment in Cuffe et al., 2025, Supplementary Table 5: 7 direct trials comparing low-FODMAP with traditional advice from the British Dietetic Association and England's National Institute for Health and Care Excellence. The separate network estimate and this page's own GRADE assessment remain provisional pending examination of the published main article.	The published appendix rates this direct comparison Low for within-study bias and heterogeneity. This is the review authors' CINeMA judgment, not this page's GRADE judgment. No network effect size or additional page-assigned certainty label is carried until the published main article has been examined.
Abdominal pain, low-FODMAP diet against usual eating	Rating withheld; source check provisional	Cuffe et al., 2025, published abstract. The published main article remains unavailable; this page's GRADE assessment is provisional and withheld.	The abstract-supported effect estimate is reported in section 4. The outcome-specific bias and certainty assessment is withheld until the published main article has been examined; the effect estimate alone does not establish a certainty rating.
Bloating or distension, low-FODMAP diet against usual eating	Rating withheld; source check provisional	Cuffe et al., 2025, published abstract. The published main article remains unavailable; this page's GRADE assessment is provisional and withheld.	The abstract-supported effect estimate is reported in section 4. The outcome-specific bias and certainty assessment is withheld until the published main article has been examined; the effect estimate alone does not establish a certainty rating.
Bowel habit, low-FODMAP diet against usual eating	Rating withheld; source check provisional	Cuffe et al., 2025, published abstract. The published main article remains unavailable; the comparison-specific estimate and this page's GRADE assessment are provisional and withheld.	Section 4 gives the published abstract's bounded finding. No comparison-specific number or GRADE deduction is taken from the accepted manuscript while the published-version check remains incomplete.
Symptom control 6 months or more after reintroduction and personalization	Very low	This page's own judgment, using GRADE. Follow-up studies without comparison groups (O'Keeffe et al., 2018; Silva et al., 2025; Staudacher et al., 2022), adults taught the diet by specialist dietitians, with follow-up of up to 13 years.	Observational studies start low. Lowered 1 level for risk of bias: no comparison group, people who did well may have been more likely to take part, and the longest follow-up relied on recall. A 2025 meta-analysis of long-term use was not used, because its abstract does not describe the included designs (Pouladi et al., 2025). The 6-month results of the CARIBS trial compared 2 diets, not the diet against usual eating.
Lower abundance of Bifidobacteria in stool, low-FODMAP diet against control diets, 3 to 4 weeks	Moderate, for the direction of the change	This page's own judgment, using GRADE. So et al., 2022: 9 randomized trials with 403 adults with irritable bowel syndrome, 7 of which reported Bifidobacteria.	Randomized trials start high. The review generally judged risk of bias low for microbiome outcomes, which are less vulnerable to participants' knowledge of diet than self-reported symptoms. Some assessor-blinding and reporting concerns remain. The consistent direction across direct comparisons supports retaining the rating for direction only, so it was not lowered for risk of bias. Not lowered for inconsistency: all 4 trials that compared groups directly found lower abundance, and the one trial that found no change measured it in a different way. Lowered 1 level for imprecision, because the review gave no pooled estimate and the trials were small and used different methods. The rating covers the direction of the change, not its size, and says nothing about whether the change affects health.
Symptom benefit in children aged 4 to 18 with irritable bowel syndrome or functional abdominal pain, strict low-FODMAP diet	No conclusion reached at low certainty or above	Groen et al., 2025, the European and North American pediatric guideline, using GRADE.	The guideline found no efficacy conclusion that reached at least low certainty and therefore made a conditional recommendation against the strict diet. Its evidence summaries are in a supporting file this page did not open. The rating is carried as published.

How this archive talks about weight. This page reports what studies measured, including body weight, and does not treat weight change as a goal or as a measure of a diet's success. Weight a person loses without meaning to can be a sign of a health problem, and where it is, the page names it as a reason to see a clinician. People are described the way the study described them.

Status: reviewed and approved by James Peth, MS, MPH, PhD, on October 4, 2026, after a combined final review of 5 archive pages, a focused recheck and a final confirmation. Written October 3, 2026, and repaired after the combined review, focused recheck and final confirmation. The spelt-sourdough and CARIBS repairs are complete. Cuffe's published main article remains unavailable. Findings on this page attributed to that review are limited to its published abstract and separately examined published appendix. Manuscript-only estimates and dependent page-assigned ratings are withheld pending published-version reconciliation. The direct-evidence CINeMA labels are carried as published; other ratings identify their own methods and sources.

What changed: After the focused recheck, the gluten myth again says that traditionally fermented spelt sourdough, not every spelt product, can be low in FODMAPs, citing Monash's own explanations; the CARIBS row and the paragraph comparing the diet with medication now say what a response meant and keep the trial's response result separate from its symptom-score result; the highlighted-studies introduction now says all 4 highlighted trials were read in full; and manuscript-only estimates and dependent page-assigned ratings from the 2025 network meta-analysis are withheld until the published main article can be examined. After the final confirmation, the findings this page takes from that review rest only on its published abstract and published appendix, and this page's own ratings for 4 outcomes are withheld.

Earlier changes: After the combined final review, the banner names its rating tool in the archive's new form; the statement that no breastfeeding study exists was corrected and a breastfeeding trial added; the statements about cancer and blood lipids were narrowed and a cancer-treatment trial added; the reintroduction sentence, the gluten myth, the first myth's last sentence, the scope box's disordered-eating reason and the Bifidobacteria wording were revised; the reasons for 2 of the page's own ratings were rewritten; the introduction and caption of the rating table follow the template; and the highlighted studies were checked against 3 full texts and the CARIBS correction.

Next scheduled review: August 2027. Pages built on annual guidance are rechecked each year. The gastroenterology guidelines cited on this page are from 2021 and 2022, and updates to them should be checked first.

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Diet Reference Archive | One James

Prepared by James Peth, MS, MPH, PhD

© 2026–2027 One James. All rights reserved.

This page is for education and coaching practice. It is not medical or dietary advice.