IBS and Diet Management, which diets can help with symptoms

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Irritable Bowel Syndrome (IBS) is a common gastrointestinal disorder, it's typically diagnosed by characterising and assessing symptoms such as abdominal pain/stomach ache, bloating, and altered bowel habits. Diet can play an important role in symptom management, although the most helpful approach varies from person to person. Our guide provides an overview of the main dietary strategies used in IBS, including elimination approaches, low FODMAP eating, fibre management, and trigger food identification.

Read our complete guide on IBS to learn more about IBS and how it is diagnosed.

How does diet influence IBS?

Diet directly influences gut function, and for individuals with IBS, certain foods can trigger symptoms while others may be better tolerated. This connection is important when developing a practical long term strategy for managing IBS, particularly if an individual is able to identify what foods trigger symptoms.

It is also important to note that there is no single “IBS diet” that works for everyone, some people may react better to elimination diets, others to low FODMAP foods. The most effective approach is usually personalised and based on symptoms, tolerance, and which IBS subtype someone may have. 

What is the current advice for IBS?

Before moving to more restrictive diets, many people with IBS benefit from getting the basics right. General advice includes eating regular meals, avoiding long gaps between eating, drinking enough fluid, reducing alcohol and fizzy drinks, and limiting excess caffeine. Some people with bloating may also find oats and linseeds helpful.

Increasing physical activity as well as relaxation time is also something that is recommended.

NHS guidance on IBS also suggests some adjustments that may seem counterintuitive. This includes limiting fresh fruit to no more than three portions per day, and being cautious with high fibre foods such as nuts, seeds and brown rice, which despite being broadly beneficial for general health, can worsen bloating and other IBS symptoms in some people. This does not mean avoiding fruit or fibre altogether, but rather being mindful of quantity and type.

Dietary changes are often only one part of IBS management. Depending on symptoms, treatment may also include other options recommended by a GP, such as antispasmodics or peppermint oil for abdominal pain.

Elimination diet

An elimination diet is a targeted approach to identifying your specific trigger foods.

An elimination diet involves removing suspected foods that trigger symptoms for a short period and then reintroducing them in a structured way. This can help identify whether particular foods are linked to your IBS symptoms by monitoring any symptoms triggered during the reintroduction phase and being able to identify which foods may have caused them. 

Elimination diets usually have 2 phases

• Elimination: Remove the suspected trigger food or group of foods for a short period.
• Reintroduction: Reintroduce foods one at a time while monitoring for any recurrence of symptoms.

How can it help IBS?

An elimination diet can help you identify foods that appear to worsen your IBS symptoms. Once those foods have been identified, the long term goal is not to remain overly restrictive, but to build a sustainable diet that avoids those specific trigger foods while still ensuring nutritional needs are met daily.

What symptoms can it help with?

Everyone’s IBS symptoms are different, however following an elimination diet can effectively reduce various IBS symptoms, particularly bloating, gas, diarrhoea, and constipation.

The low FODMAP diet

The low FODMAP diet is one of the best studied dietary approaches for IBS, some studies have reported response rates as high as 86%, though results vary from person to person. FODMAPs are fermentable carbohydrates that can increase water in the bowel and be rapidly fermented by gut bacteria, which can trigger symptoms such as bloating, abdominal pain, and diarrhoea in some people.

There are foods that are high in FODMAPs and foods that are low in FODMAPs. A low FODMAP diet focuses on reducing high FODMAP foods and choosing lower FODMAP alternatives, which can help ease symptoms in some people with IBS.

High and low FODMAP foods

• High FODMAP foods: Onions, garlic, apples, wheat, some dairy products containing lactose, and certain sweeteners such as sorbitol.
• Lower FODMAP foods: Examples include bananas, grapes, eggs, meat, carrots, cucumbers, and suitable lactose free or low lactose options depending on the person.

How does it help with IBS?

A low FODMAP diet may help reduce bloating, abdominal pain, gas, and diarrhoea in some people with IBS. It is usually intended as a short term elimination and reintroduction process rather than a permanent diet.

What symptoms can a low FODMAP diet improve?

It is most commonly used for  bloating, abdominal pain, wind, and diarrhoea related symptoms, although some people with mixed IBS may also benefit.

Fibre and IBS

Not only can fibre help to improve the diversity of our gut microbiome, it can also be helpful in IBS, but the type of fibre and which IBS subtype an individual suffers from matters. Soluble fibre is generally better tolerated than insoluble fibre and may be more helpful for overall IBS symptoms. 

Soluble vs insoluble fibre

• Soluble Fibre: This type of fibre dissolves in water to form a gel like substance. It can help soften stools in constipation and may also help improve stool consistency in some people with diarrhoea predominant IBS. Examples include oats, psyllium, and some fruits. 
• Insoluble Fibre: This type of fibre does not dissolve in water and adds bulk to the stool. In some people with IBS, especially those with diarrhoea or bloating, it can make symptoms worse. Examples of insoluble fibre include bran and some wholegrain products.

How does fibre help with IBS?

Soluble fibre may help regulate bowel movements and improve overall IBS symptoms, particularly in constipation predominant IBS. However, too much fibre introduced too quickly can worsen bloating and gas, so any increase should be gradual and dependent on your IBS subtype.

Sources of soluble fibre

• Oats and oat bran
• Psyllium husk
• Fruit such as bananas, berries, and apples, depending on tolerance
• Vegetables such as carrots
• Some legumes, although tolerance varies and these can be high FODMAP for some people

How to adopt a higher fibre diet with IBS

• Increase fibre gradually rather than all at once
• Focus more on soluble fibre if IBS symptoms tend to flare with bran or coarse fibres
• Drink enough fluid as you increase fibre intake
• Monitor symptoms, reactions to fibre vary from person to person

In the UK, adults are generally advised to aim for around 30g of fibre per day for overall health, but people with IBS may need to adapt this according to tolerance.

Gluten and IBS

Some people with IBS notice that wheat or gluten containing foods seem to worsen their symptoms. In some cases, this may relate to gluten itself, while in others it may be related to fructans, which are considered a high FODMAP food, or other components of these foods.

A gluten free diet is not necessary for everyone with IBS, but eliminating gluten for a short period may be beneficial for some individuals and their symptoms.

Read our guide on everything there is to know about gluten intolerance.

Avoiding your trigger foods

Avoiding trigger foods is similar to an elimination diet and arguably the most simple diet that can be implemented to help with symptoms. By identifying and reducing foods that you know to worsen your IBS symptoms, you may be able to reduce both the severity and frequency of symptoms over time.

How to identify your trigger foods

• Food diary: Keeping a detailed food diary can help you identify individual triggers. Making a note of all the foods you have consumed daily as well as logging your IBS symptoms can help you to pinpoint your triggers.

Common trigger foods

There is no rule of thumb when it comes to trigger foods as everybody will have different triggers. However most common trigger foods may include high fat foods, caffeine, alcohol, spicy foods, large meals, and highly processed foods, although triggers vary between individuals.

Foods that may be better tolerated in IBS

Many people with IBS find that symptoms are easier to manage when meals are based around simpler, less irritating foods. Depending on tolerance, examples can include:

• Lean proteins: Often easier to tolerate than very fatty meals, which can worsen symptoms in some people. Examples include skinless chicken or turkey, white fish, salmon, eggs, tofu, tempeh, and lean cuts of beef or pork.
• Lower FODMAP fruits and vegetables: May help reduce bloating, gas, and abdominal discomfort in people who are sensitive to fermentable carbohydrates. Examples include bananas, grapes, blueberries, strawberries, oranges, carrots, courgettes, cucumbers, spinach, peppers, and potatoes. However it's important to remember NHS guidance that advises against consuming more than 3 portions of fruit daily.
• Lactose free dairy or suitable alternatives where needed: May be helpful where lactose appears to trigger symptoms. Examples include lactose free milk, lactose free yogurt, hard cheeses such as cheddar or parmesan, and fortified plant based alternatives that are low in FODMAPs.
• Oats and other soluble fibre rich foods: May help support stool consistency and are often better tolerated than insoluble fibre. Examples include oats, oat bran, psyllium husk, chia seeds, flaxseeds, and some fruits such as bananas and peeled apples, depending on tolerance.
• Non caffeinated beverages: Useful where caffeine appears to worsen urgency, diarrhoea, or abdominal discomfort. Examples include water, peppermint tea, ginger tea, and other caffeine free herbal teas that are well tolerated.
• Healthy fats in moderate amounts: Very high fat meals can worsen symptoms in some people, so moderate portions are often better tolerated. Examples include olive oil, avocado, nut butters, seeds, and small portions of nuts, depending on individual tolerance.
  

No food is universally “good” or “bad” for IBS. Personal response remains one of the most important factors in choosing a sustainable long term diet.

What is the best diet for IBS?

There is no “one size fits all” when it comes to the best diet for IBS; foods that may trigger your symptoms may not trigger symptoms in someone else. A highly personalised approach is the best diet to adopt to help with the management of your symptoms and overall experience with IBS.

For some people, simple dietary changes are enough. For others, more structured approaches such as a low FODMAP diet, a carefully planned elimination diet, or a fibre focused approach may be more helpful. Restrictive diets should ideally be short term and reviewed with a registered dietitian where possible.

A gut health test that also screens for intestinal parasites may be useful in some cases, because gut parasites such as Giardia can cause symptoms that closely resemble IBS, including bloating, abdominal pain, and diarrhoea. In some people, gastrointestinal infection may also be followed by post infectious IBS, so identifying or ruling out an infectious cause can be important when symptoms are ongoing or began after travel or gastroenteritis.

Can you cure IBS with diet?

Diet is a key element in managing IBS symptoms, but it's important to understand that IBS is a chronic condition, of which there is currently no cure for. While dietary changes can significantly improve quality of life and help to regulate symptoms, they are not a cure for IBS. These dietary strategies should be part of a comprehensive multifaceted management plan, also including a number of lifestyle changes and in some cases may require treatment.

At present, there is not a cure for IBS, however; there are a number of IBS treatments that effectively help to reduce symptoms and allow sufferers to live normal active lives.

How long does it take to see improvements in IBS symptoms after dietary changes?

The time frame can vary. Some people may notice improvements within days, while for others it may take several weeks, particularly when trialling a low FODMAP diet or slowly increasing fibre intake. On the other hand, dietary changes alone may not be enough to experience any improvements in IBS symptoms.

Are there any risks associated with specific IBS diets?

Restrictive diets such as low FODMAP, gluten free, or more extensive elimination diets can increase the risk of nutritional imbalances if not implemented carefully. It is best to undertake these diets under the guidance of a Registered Dietitian or other qualified healthcare professional with expertise in dietary management.

Do people with IBS need to avoid dairy products?

Not necessarily. Some people with IBS are also lactose intolerant, while others tolerate dairy without difficulty or experiencing any symptoms. Fermented dairy can be nutritious and may be tolerated by some people, so removing it unnecessarily may not always be helpful. The right approach depends on individual symptoms and response.

How important is hydration in an IBS-friendly diet?

Hydration is important for digestive health and becomes even more important when increasing fibre intake. Adequate fluid intake may help with constipation and supports the way fibre works in the gut.

Can stress and diet together influence IBS symptoms?

Yes. Stress can worsen IBS symptoms on its own through the gut-brain axis, and dietary triggers can also exacerbate this alongside it. Managing stress alongside diet is often an important part of IBS symptom control.

Is it necessary to permanently follow a restrictive diet for IBS?

Not always. Some diets, such as low FODMAP or elimination diets, are usually intended to be temporary. The aim is to identify triggers and build a longer term diet that is as varied and sustainable as possible.

Summary

Managing IBS through diet requires an understanding of how different foods affect individual symptoms. There is no single diet that works for everyone. For many people, the most effective strategy is a personalised one that may include basic dietary changes, food diary tracking, soluble fibre adjustments, or a structured low FODMAP or elimination approach.

If symptoms are severe, persistent, or changing, it is important to seek medical advice rather than relying on diet changes alone.

References

[1] National Institute for Health and Care Excellence. Irritable bowel syndrome in adults: diagnosis and management. https://www.nice.org.uk/guidance/cg61/chapter/1-recommendations

[2] National Institute of Diabetes and Digestive and Kidney Diseases. Eating, Diet, & Nutrition for Irritable Bowel Syndrome. https://www.niddk.nih.gov/health-information/digestive-diseases/irritable-bowel-syndrome/eating-diet-nutrition

[3] Lacy BE, Pimentel M, Brenner DM, et al. ACG Clinical Guideline: Management of Irritable Bowel Syndrome. American Journal of Gastroenterology. 2021. https://webfiles.gi.org/links/PCC/ACG_Clinical_Guideline__Management_of_Irritable.11.pdf

[4] British Dietetic Association. Fibre. https://www.bda.uk.com/resource/fibre.html

[5] Black CJ, Ford AC. Best management of irritable bowel syndrome. Frontline Gastroenterology. 2021. https://fg.bmj.com/content/12/4/303