One in five Australians gets the symptoms of irritable bowel syndrome: bloating, pain, gas, diarrhoea, constipation. Often these symptoms are undiagnosed, or self-diagnosed. It’s common to blame gluten or lactose, but far fewer people are actually intolerant than the number of those who think they are. So what is causing these symptoms? The culprit might be FODMAPs.

What are FODMAPS?
FODMAPS are a group of carbohydrates. The name stands for fermentable oligo-, di- and mono-saccharides, and polyols. These carbohydrates are fermented in the intestines, and so increase the volume of liquids and gas in the gut.

Most of us don’t have any trouble digesting the level of FODMAPs found in a standard diet. But some people don’t absorb FODMAPs as well as others. This means there are more left in the intestines, meaning more fermentation occurs, leading to more liquid and gas. Too much liquid and gas can lead to symptoms including pain, gas, bloating, diarrhoea and constipation.

FODMAP foods may also have a cumulative effect. This means you might not get symptoms every time you eat a particular food; it depends on the combination of foods you are eating.

FODMAP foods
Many common foods are high in FODMAPs. They include wheat breads, milk and some dairy products, which may explain why people often blame gluten and lactose. Examples of high FODMAP fruit and veg include garlic, asparagus, onion, apples, pears, peaches and legumes. Researchers from Melbourne's Monash University have developed a low-FODMAP diet to help reduce IBS symptoms.

Companies are now creating “lo-fo” product replacements, including low FODMAP breads made from low FODMAP grains, but which still contain gluten. Certification programs are starting to pop up too, labelling foods as “FODMAP friendly” or “low FODMAP certified”. Remember though, these are commercial trademarks and not run by official bodies, so requirements for certification will vary.

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Can you remove FODMAPs from food?
Processing foods can alter the FODMAP content. Pickling and canning, for example, can leach the FODMAPS from the food into the surrounding liquid. But FODMAPs don’t dissolve in oils, so you can use oils infused with garlic and onion to add flavours to foods, without actually eating them. So avoiding FODMAPs can be as much about cooking and preparation as which foods you eat. Serving size matters too – some foods may only cause symptoms if consumed in large amounts, so you don’t need to completely exclude FODMAPs to improve your symptoms.

Should I follow a low-FODMAP diet?
Lots of very nutritious foods contain FODMAPs, and it can be hard to maintain a balanced diet and to figure out which things you respond to. By excluding FODMAPs, you risk reducing your intake of healthy fibre and pre-biotics important for gut health.

The Monash team and others have developed online and smart phone tools. But, if you think you are FODMAP sensitive, the best course of action is to find a dietitian who can advise you. Be careful. The title of a dietitian is not protected in Australia. Look for an accredited practicing dietitian – this means they have a university qualification and participate in ongoing professional development to ensure they are giving you the best and most up-to-date information. FODMAPs are a rapidly developing field and information online can become outdated quickly.

Dr Emma Beckett is Broadsheet’s nutrition columnist. A molecular nutritionist with a PhD in Food Science, she is a post-doctoral fellow in the School of Medicine and Public Health and the University of Newcastle. In a world of mixed messages she can be found busting nutrition myths and empowering people to critically assess nutrition information. She tweets at @synapse101.