IBS and diet: what should you eat, and what should you avoid?

Introduction

Irritable bowel syndrome (IBS) can make eating feel complicated. Advice online ranges from avoiding gluten and dairy to cutting out fibre, carbohydrates or entire groups of plant foods.

But there is no single "IBS diet" that works for everyone. Different foods can trigger symptoms in different people, and restricting more foods isn't necessarily better.

Dietary changes can make a meaningful difference to IBS symptoms. The key is finding an approach that improves symptoms while keeping your diet as varied and nutritious as possible.

What is IBS?

Irritable bowel syndrome (IBS) is a common disorder of gut-brain interaction. It affects how the gut and brain communicate and can change how sensitive the gut is and how food and waste move through it.

IBS should not be confused with inflammatory bowel disease (IBD). Despite their similar names, they are different conditions. IBD, which includes Crohn's disease and ulcerative colitis, involves chronic inflammation that can cause visible damage to the digestive tract. IBS is not characterised by ongoing inflammation or tissue damage, although its symptoms can still significantly affect quality of life.

Typical symptoms of IBS include abdominal pain, bloating and changes in bowel habits. Some people predominantly experience constipation (IBS-C), others diarrhoea (IBS-D), while some alternate between the two (mixed IBS, or IBS-M).

There is no single test for IBS. Diagnosis is generally based on a characteristic pattern of symptoms, while considering whether tests are needed to rule out other conditions. NICE recommends blood tests including a full blood count, inflammatory markers and screening for coeliac disease as part of the diagnostic process.

When should you speak to a doctor?

Digestive symptoms shouldn't automatically be assumed to be IBS. If you've developed persistent or unexplained changes in bowel habits, it's worth speaking to your doctor.

You should seek medical advice promptly if you have unexplained weight loss, rectal bleeding or blood in your stool, a lump or swelling in the abdomen, or other concerning changes that may require further investigation.

How can food affect IBS?

Food is one of the most commonly reported influences for IBS symptoms, but that doesn't necessarily mean a particular food is damaging the gut or that you are "intolerant" to it.

Different foods can affect the digestive system in different ways. Some short-chain carbohydrates aren't completely absorbed in the small intestine, for example. For some people they can draw water into the bowel and are then fermented by gut bacteria, producing gas.

These are normal physiological processes. But in someone with a particularly sensitive gut, the resulting stretching of the intestine can contribute to pain, bloating or changes in bowel habits.

Meal size, fat content, fibre, caffeine and alcohol can also influence gut motility or symptoms. This helps explain why IBS can be so individual: a food that causes significant symptoms in one person may cause no problems at all in another.

So, what is the best diet for IBS?

There isn't one best diet for everyone. A good approach is generally to start with relatively simple changes before considering more restrictive or specialised diets.

NICE recommends measures such as eating regular meals, avoiding long gaps between meals, drinking adequate fluids and considering whether caffeine, alcohol or fizzy drinks aggravate symptoms.

If symptoms continue, more targeted dietary strategies can then be explored with a healthcare professional such as a dietitian.

A useful principle is: start simple, identify genuine triggers, and avoid restricting foods unnecessarily.

Fibre and IBS: is more always better?

Fibre is important for digestive health, but when it comes to IBS, simply telling everyone to "eat more fibre" isn't particularly helpful. The type and amount of fibre matter, and people can respond differently.

Insoluble fibre, particularly wheat bran, can worsen symptoms in some people with IBS. Soluble fibres such as psyllium (also known as ispaghula husk) are generally better tolerated and can help regulate stool consistency.

A 2026 systematic review and meta-analysis of 30 randomised trials found that fibre supplementation improved the likelihood of a clinical response overall, with a specific benefit found for psyllium, although the review found no significant overall improvement in gastrointestinal symptom scores across all fibre types.

NICE recommends soluble fibre, including oats, when increasing fibre intake in people with IBS. That doesn't mean everyone with IBS should avoid whole grains or other high-fibre foods. Rather, the amount and type of fibre may need to be adjusted according to symptoms.

And if you're increasing fibre, doing so gradually is usually more comfortable than suddenly adding large amounts.

Which foods should you avoid with IBS?

There isn't a universal list.

Some people find that common dietary triggers can include very large or fatty meals, alcohol, caffeine and certain sweeteners, and the type and amount of fibre in various foods. But individual tolerance varies considerably.

The aim should be to identify repeatable, meaningful triggers, rather than accumulating an ever-growing list of forbidden foods.

What is the low-FODMAP diet?

The low-FODMAP diet is one of the best-known dietary treatments for IBS. FODMAP stands for:

Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols.

These are groups of short-chain carbohydrates that are poorly absorbed or slowly absorbed in the small intestine.

They include:

•  Fructans, found in foods such as wheat, onions and garlic  

•  Galacto-oligosaccharides (GOS), found in foods including beans and some other pulses  

•  Lactose, found in milk and some dairy products  

•  Excess fructose, found in some fruits and sweeteners  

•  Polyols, including sorbitol and mannitol, found naturally in some fruits and vegetables and used in some sugar-free products

FODMAPs can increase the amount of water in the intestine and are fermented by gut bacteria, which can increase gas production. For some people with IBS, particularly those with a sensitive gut, this can contribute to symptoms such as pain, bloating and diarrhoea.

The low-FODMAP diet is usually carried out in stages, after exploring other common triggers such as high fat meals and excess caffeine. It involves reducing FODMAPs for a limited period, gradually reintroducing them and then developing a more personalised diet based on individual tolerance. It is best undertaken with support from a dietitian or other healthcare professional with expertise in dietary management.

Does a low-FODMAP diet work?

For some people, yes. A 2022 systematic review and network meta-analysis of 13 randomised controlled trials found that a low-FODMAP diet improved global IBS symptoms and ranked highly for reducing abdominal pain and bloating or distension, although it was not clearly better than other approaches for bowel habits.

A larger 2025 network meta-analysis reached a similar overall conclusion: several dietary approaches showed promise, but the low-FODMAP diet currently has the largest evidence base. The authors also noted that confidence in many comparisons between diets remains low.

So, low FODMAP isn't a guaranteed solution, and it isn't necessarily the best approach for every individual. But it is one of the better-supported dietary interventions for IBS, particularly when simpler dietary advice has not helped.

A low-FODMAP diet isn't supposed to be permanent

This is an important point. A properly implemented low-FODMAP diet isn't simply a long list of foods that you can never eat again.

It typically involves three stages:

1.  Restriction: Higher-FODMAP foods are temporarily reduced to see whether symptoms improve.  

2.  Reintroduction: Different FODMAP groups are systematically reintroduced to identify which ones actually cause symptoms and at what amounts.  

3.  Personalisation: Foods that are tolerated are brought back into the diet, aiming for  the least restrictive diet that adequately controls symptoms.

This matters because unnecessarily restrictive diets can make eating socially difficult, reduce dietary variety and potentially compromise nutrient intake. Research has identified nutritional considerations around restrictive low-FODMAP diets, particularly when they aren't appropriately managed.

NICE recommends that exclusion diets such as low FODMAP are undertaken with advice from a healthcare professional with expertise in dietary management.

The goal isn't to eat as few FODMAPs as possible forever. It's to work out which foods you tolerate and how much of them you can comfortably eat.

Do you need to avoid gluten if you have IBS?

Not necessarily. Many people with IBS report feeling better when they stop eating wheat and conclude that gluten must be responsible. But wheat contains more than gluten. It is also a major source of fructans, which are FODMAPs.

One double-blind crossover trial provides an interesting demonstration of this. Researchers gave people who reported gluten sensitivity foods containing gluten, fructans or neither. In this study fructans produced more gastrointestinal symptoms than gluten, while symptoms after gluten were not significantly different from placebo.

This doesn't prove that fructans explain every case of self-reported gluten sensitivity, but it demonstrates why feeling better after removing wheat doesn't necessarily mean gluten was the culprit.

This also doesn't mean that everyone with IBS needs to avoid fructans. Some gluten-containing foods are relatively low in fructans and may be well tolerated, while reducing fructans alone may not adequately improve symptoms. Other FODMAPs, or non-FODMAP factors such as meal size, fat, caffeine, alcohol or certain types of fibre, may also contribute. If symptoms persist or identifying triggers becomes difficult, advice from a suitably qualified healthcare professional or dietitian can help.

Importantly, coeliac disease is different. It is an autoimmune condition in which gluten causes damage to the small intestine.

If coeliac disease is suspected, it's important to be tested before starting a gluten-free diet, because removing gluten can make diagnostic testing less reliable. NICE  recommends testing for coeliac disease in appropriate people presenting with IBS symptoms.

What about dairy?

IBS doesn't automatically mean you need to avoid dairy. Some people have difficulty digesting lactose, the sugar naturally present in milk. If lactose isn't adequately digested in the small intestine, it passes into the large intestine, where it is fermented by bacteria and can contribute to gas, bloating and diarrhoea.

IBS and lactose intolerance can occur together, and their symptoms overlap considerably. People with IBS appear more likely to report lactose intolerance and experience symptoms after consuming lactose, although lactose malabsorption itself does not appear to be more common. This can make it difficult to tell whether lactose is actually responsible for symptoms.

Tolerance can also be dose-dependent. Some people who experience symptoms after a large glass of milk may tolerate smaller amounts of lactose or lower-lactose foods.

Importantly, lactose-free and dairy-free aren't the same thing. Some dairy products, such as hard cheeses and butter, naturally contain very little lactose, while people who prefer to avoid dairy can choose plant-based alternatives, which are naturally lactose-free. There's no need to include dairy specifically in a healthy diet, although it's important to replace the nutrients it can provide, particularly calcium and iodine.

So if dairy appears to trigger symptoms, the aim isn't necessarily to either avoid it completely or keep it in the diet. It's to work out whether lactose is contributing, how much you personally tolerate, and which foods work best for you.

What about beans and pulses?

Beans, lentils and chickpeas are sometimes placed on lists of foods to avoid with IBS because they can contain substantial amounts of GOS. But this doesn't mean everyone with IBS needs to eliminate pulses or legumes.

FODMAP content depends partly on the type of food and serving size, and some processing methods can alter it. Individual tolerance also varies. This distinction matters because pulses are nutritious foods providing fibre, protein, vitamins, minerals and other beneficial plant compounds. Rather than thinking of foods as simply "IBS-friendly" or "bad for IBS", it is often more useful to ask: What amount of this food can I comfortably tolerate?

Can probiotics help IBS?

Possibly, but this is an area where simple claims can be misleading. "Probiotics" describes a wide range of different microorganisms, strains, combinations and doses. Evidence that one probiotic helps IBS doesn't mean that every yoghurt or probiotic supplement will have the same effect.

A 2023 systematic review included 82 randomised controlled trials involving more than 10,000 people. Some probiotic strains or combinations appeared to improve particular IBS symptoms, but certainty varied substantially and only 24 trials were considered at low risk of bias across assessed domains.

More recent evidence also suggests that probiotics may improve symptom severity on average, but doesn't establish that one probiotic will work for everyone with IBS.

NICE advises people who choose to try a probiotic to take it at the manufacturer's recommended dose for at least four weeks while monitoring whether symptoms improve.

In other words, judge the specific product by whether it actually helps you, rather than assuming that more probiotics are automatically better.

Does peppermint oil help with IBS?

Peppermint oil isn't really a dietary treatment, but it's worth mentioning because it is commonly used for IBS. Peppermint oil can relax smooth muscle in the gastrointestinal tract, which may help reduce spasms and abdominal pain.

A 2022 meta-analysis of 10 randomised controlled trials involving 1,030 people found that peppermint oil was more effective than placebo for both global IBS symptoms and abdominal pain. However, adverse effects such as heartburn and acid reflux were more common and the researchers rated the quality of evidence as very low.

So peppermint oil may help some people, but it isn't a cure and the evidence isn't as definitive as some supplement marketing might suggest.

Should you keep a food and symptom diary?

It can be useful, particularly when you're trying to identify patterns. Recording what you eat alongside symptoms can help reveal repeatable associations that are difficult to notice from memory alone.

But be cautious about blaming every bad day on the last thing you ate. IBS symptoms naturally fluctuate, and food isn't the only factor involved. Stress, sleep, physical activity, hormones and other aspects of health can all influence symptoms.

A useful diary therefore looks for patterns over time, rather than eliminating a food every time symptoms happen to follow it. If you start removing more and more foods without a clear pattern emerging, it might be time to seek professional guidance rather than restricting further.

Can diet cure IBS?

There currently isn't a dietary cure for IBS. Diet can substantially improve symptoms for some people, but IBS is a disorder of gut-brain interaction rather than simply a reaction to particular foods.

That distinction is important, because it explains why two people can eat exactly the same meal and experience it very differently. It also explains why treatments that don't involve changing food (including certain medications and gut-directed psychological therapies) can also improve IBS symptoms. The American College of Gastroenterology, for example, suggests gut-directed psychotherapy as a treatment option for global IBS symptoms.

This doesn't mean symptoms are "all in your head". The brain and digestive system communicate continuously, and changes in this relationship can produce very real gastrointestinal symptoms.

Should you get a food intolerance test?

Be cautious. Commercial "food intolerance" tests are widely marketed to people with digestive symptoms, often promising to identify dozens of foods that should be avoided.

In particular, tests based on food-specific IgG antibodies don't establish that a food is causing IBS symptoms. IgG responses to foods commonly reflect exposure to those foods rather than a clinically meaningful intolerance.

Removing foods on the basis of unreliable tests can lead to increasingly restrictive diets without addressing the actual cause of symptoms.

If you suspect a particular food is consistently causing problems, discussing this with a doctor or registered dietitian is more useful than ordering a broad commercial intolerance panel.

Do you need a restrictive diet at all?

Not necessarily, and this is perhaps the most important takeaway. IBS dietary advice has increasingly become associated with the low-FODMAP diet, but that doesn't mean everyone diagnosed with IBS should immediately start eliminating FODMAPs.

Current guidance recommends beginning with general dietary and lifestyle measures. More restrictive approaches can then be considered when symptoms persist.

And the evidence base is continuing to develop. A 2025 review of 28 randomised trials found promising results for several different dietary approaches, while concluding that the largest body of evidence currently exists for low FODMAP.

The best diet isn't necessarily the one that removes the most potential triggers.

It's the least restrictive diet that provides adequate symptom control while remaining nutritious, varied and practical to live with.

The bottom line

There is no universal diet for IBS. For many people, a sensible starting point is to eat regular meals, drink enough fluid and consider whether specific factors such as caffeine, alcohol, very large meals or the type and amount of fibre they eat are contributing to symptoms.

Soluble fibre, particularly psyllium, can help some people. A low-FODMAP diet has one of the strongest evidence bases among dietary interventions for IBS, particularly for symptoms such as bloating and abdominal pain. But it is designed to identify individual tolerances through restriction, reintroduction and personalisation. Not to provide a permanent list of foods to avoid.

Gluten, dairy, beans and other commonly blamed foods don't need to be universally eliminated either. The relevant trigger may be a particular carbohydrate, the amount eaten, or something else entirely.

If your symptoms are persistent, haven't been diagnosed, or you're finding yourself cutting out an increasing number of foods, speak to your doctor or a registered dietitian. Good IBS management should help you expand what you can comfortably eat where possible, rather than making your diet progressively smaller.