• IBS is a common condition, affecting about 30% of Australians. 
• There is no known cause, but factors that contribute to its development may include stress, infection and medication.  
• Dietary strategies are often helpful in managing IBS symptoms, and may include changes like fibre and fluid modification, changes to eating behaviours, and/or elimination diets. 
• Around 3 in 4 people see improvements in IBS symptoms within a few days to weeks of adopting a low-FODMAP diet. 
• The low-FODMAP diet involves temporarily restricting high-FODMAP foods. These are short--chain carbohydrates which are poorly digested in the small intestine. These carbohydrates are then fermented by gut bacteria  in the colon, which can trigger symptoms like gas, bloating, and abdominal pain in people who are sensitive  
• The goal of a low FODMAP diet is to identify which FODMAPs are personal triggers, so that non-problematic foods can be reintroduced for the long term. 
• A strict low-FODMAP diet should only be followed short-term. Please seek the advice of a dietitian with experience in the low-FODMAP diet to develop a personalised approach for you. 

4 minute read

What is IBS?

Irritable bowel syndrome (IBS) is a disorder of gut brain interaction meaning the communication pathway between the gut and the brain is not working properly. It can cause a variety of uncomfortable symptoms. 

Symptoms of IBS include: 

• abdominal pain 
• wind 
• constipation and/or diarrhoea 
• bloating 

These symptoms are also common in other bowel conditions. It's important to consult a doctor to rule out other conditions before IBS can be diagnosed.  

Up to 30% of Australians suffer from IBS. The condition occurs more often in females. While it can present at any age, it most often occurs before the age of 40.  

What causes IBS?

The causes of IBS are often unclear, but many people find it presents after an episode of gastroenteritis, food poisoning, infection, illness or chronic stress.  

Food plays a role in triggering IBS symptoms for many people, but the foods that trigger symptoms will vary for each person. 

Symptoms and severity often change over time. Periods of high stress are known to worsen IBS symptoms in some people. 

Treatment of IBS

IBS is a chronic condition, requiring long-term management, but symptoms can wax and wane over time and treatment may only be required intermittently.  

Various management strategies exist for IBS. These include prescribed and over-the-counter medications, and drug-free approaches. 

Gut-directed hypnotherapy is gaining increasing attention for its efficacy in managing IBS symptoms. This is an alternative or complementary treatment option alongside dietary management. 

Often, changes to your diet are all it takes to improve or lessen IBS symptoms. Working with an Accredited Practising Dietitian (APD) can help you identify which foods are your personal triggers. This allows you to reduce your intake of these triggers, without missing out on key nutrients in your diet. 

Diet and IBS

Dietary strategies are often very effective in managing the symptoms of IBS. While foods which increase gut sensitivity are different for everyone, general dietary tips include: 

• Eat more high-fibre foods, like fruit and vegetables, legumes and wholegrains 
• Eat less gas-producing foods. These include onion, cabbage, brussels sprouts, cauliflower, dried beans and lentils 
• Eat fewer foods containing lactose, like milk, ice cream and some yoghurts (for suitable alternatives view our lactose intolerance health advice page)  
• Drink less alcohol 
• Reduce your intake of caffeine 
• Limit spicy foods 
• Limit high-fat foods, like deep-fried or oily foods 
• Limit your intake of food and drinks which contain artificial sweeteners particularly ones ending in ‘ol’, such as sorbitol and mannitol. 

Some people will have an improvement in their IBS symptoms by adopting the changes mentioned above, like eating a high fibre diet by eating more wholegrains, fruit and vegetables. A more specific strategy for addressing IBS is to adopt a low-FODMAP diet for 2-6 weeks. This may help to initially settle symptoms down before being able to identify trigger foods through a structured reintroduction (challenge) process. 

What are FODMAPs?

FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. These are types of carbohydrate (sugars), which are poorly absorbed in the small intestine.  

When these carbohydrates are poorly absorbed they travel to the large intestine (colon). There they attract water into the gut and are fermented by the healthy gut bacteria, increasing gas. 

The increased water can result in diarrhoea for some people. The gas resulting from fermentation can also lead to symptoms of bloating, constipation, flatulence and pain.  

Common high FODMAP foods include garlic, onion, apples, milk, mushrooms, wheat bread and legumes like chickpeas. 

How can FODMAPs help manage IBS?

Research has proven that following a low-FODMAP diet is one of the most effective dietary interventions for managing IBS for many individuals. Around 3 in 4 people see improvements in their symptoms within a few days to weeks after adopting this approach. 

The diet involves temporarily reducing your intake of high FODMAP foods. This is then followed by a structured reintroduction (challenge) phase, where foods are gradually added back to identify personal triggers. An Accredited Practising Dietitian (APD) can help guide you through this process to ensure it’s done safely and effectively. 

How long do I stay on a low-FODMAP diet?

While a strict low FODMAP diet can be a diagnostic tool, it's not recommended you stick to it in the long term. After the elimination phase, it’s important to complete the reintroduction (or challenge) phase to pinpoint which specific FODMAPs are contributing to your symptoms. 

It's important to avoid restricting all high-FODMAP foods long term  because: 

• Many high-FODMAP foods are also high in prebiotics. Prebiotics are a specific type of fibre that feed the healthy bacteria in your gut. Avoiding these long-term can affect the health of your gut microbiome. 
• Most people can tolerate at least some of the high-FODMAP food groups.  
• By identifying which foods are most bothersome, you can re-introduce groups that aren't a problem for you. You can make informed food choices, and manage symptoms on a daily basis. 
• Avoiding unnecessary restrictions helps ensure you're getting the nutrients you need. It increases variety in your diet.