Athletes of all levels can be troubled by uncomfortable symptoms such as abdominal pain, bloating, wind and altered bowel movements, commonly referred to as Irritable Bowel Syndrome (IBS). These symptoms can create anxiety and stress, can interfere with training, and may compromise performance. In some individuals, abdominal symptoms can be triggered by certain foods, in particular by a group of poorly absorbed, rapidly fermentable carbohydrates known as FODMAPs – an acronym for Fermentable Oligo-, Di- and Mono-saccharides And Polyols. Fructose, fructans, lactose, sorbitol, and xylitol are common examples, and limiting or avoiding foods high in FODMAPS may help to manage or reduce symptoms.

FODMAPs are not the cause of IBS but there are now several good quality studies indicating that FODMAPs can be dietary triggers for IBS and functional gut symptoms, and the low FODMAP diet is now written in the Therapeutic Guidelines as the preferred dietary therapy for symptoms of IBS in Australia.

Fructans and Galacto-oligosaccharides (GOS)

Fructans and GOS cannot be absorbed in the small intestine at all (the gut lacks the enzymes to break them down so they ferment in the colon) so certain amounts will always cause symptoms. In people with IBS, symptoms are experienced earlier than in those people without IBS.

Fructose 

Fructose is a monosaccharide found in three main forms:

• As free fructose (present in fruits and honey, high fructose corn syrup)
• As fructans (chains of fructose) present in some vegetables and wheat products also known as fructo-oligosaccarides (FOS) and inulin
• Disaccharide form: sucrose (glucose + fructose)

People with fructose malabsorption do not need to avoid all fruits and foods that contain fructose – it is usually only a problem when excess fructose is present, that is, when the amount of fructose in a food is greater than the amount of glucose (see table below).

Lactose 

Lactose is found naturally in cow, sheep, and goat milk. Lactase is the natural enzyme required to digest lactose in the small intestine. Some individuals do not produce enough of this enzyme to effectively digest lactose and may experience loose bowel movements, abdominal pain, bloating, and wind.

Some people with lactose intolerance may still be able to manage small amounts of lactose in their diet without symptoms or they may choose to use lactose-free, soy, and rice alternatives which contain important nutrients for recovery post-exercise. Additionally, soy based and lactose-free yoghurts are available.

Protein powders may or may not contain lactose – it depends on the amount used and the quality of the powder. An Accredited Sports Dietitian can help you to decide the best option for you without aggravating IBS symptoms.

Diagnosis

Diagnosis of a low FODMAP diet occurs through a dietary testing process where all FODMAP foods are eliminated for a short period of time, followed by reintroduction for assessment of trigger foods. An Accredited Sports Dietitian can work with you to determine an individualised plan that will suit your unique situation.

Where are FODMAPs found?

FODMAPs are found in everyday foods and athletes should be aware of their food intolerance and plan ahead in order to help them perform in their sport. Table 1 below provides a list of foods which may cause symptoms in some people. Many common sports products (e.g. sports drinks, gels and bars) also contain FODMAPs.

Table 1:

Sourced from Dr Sue Shepherd, Accredited Practising Dietitian and Stephanie Gaskell, Accredited Sports Dietitian.

Further information

For further information on FODMAPs and what constitutes a low FODMAP diet please visit an Accredited Sports Dietitian with experience in low FODMAP dietary management. Dairy Australia also has information on lactose intolerance in this fact sheet.

Acknowledgements:

Dr Sue Shepherd developed a form of fructose malabsorption diet. Subsequently a team at Monash University, led by Professor Peter Gibson and including Dr Shepherd and others, developed the low FODMAP diet. We thank Dr Sue Shepherd, Accredited Practising Dietitian and Stephanie Gaskell, Accredited Sports Dietitian, for their invaluable knowledge and expertise in writing this fact sheet.