To FODMAP or Low-FODMAP? That is the question

Hands up if you’re familiar with the term irritable bowel syndrome? Irritable bowel syndrome, or IBS, is a condition associated with recurrent abdominal pain over a minimum of three months, which may be related to defecation, or a change in stool consistency and frequency. Sufferers may also complain of bloating and increased flatulence. If you do have any of these symptoms, it’s worth talking to your GP for a diagnosis and to first rule out other conditions. While there are many causes of IBS, such as stress, anxiety and depression, the nutritional cause of IBS is FODMAPs. As such, the first line nutrition treatment for IBS is a low FODMAP diet.

What are FODMAPs and how do they affect the gut?
FODMAPs are Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. They are all carbohydrates that can’t be or are poorly digested by the human body. Instead, these carbohydrates pass through your stomach and small intestine, ending up in the large intestine (the colon) where your gut bacteria ferment them. To paint the picture, try thinking about your colon like a compost bin, and the bacteria in your colon like the bacteria and bugs that help break down food scraps. Now, instead of producing rich compost that you can spread around your garden, your bacteria produce gas (hydrogen, carbon dioxide and methane) and short-chain fatty acids (SCFA’s) (1). SCFA’s are predominately absorbed within the colon and are responsible for stimulating fluid uptake and colonic blood flow (2). While we all produce some gas from FODMAP containing foods and we may experience some distension (enlargement) of the bowel because of the additional fluid that is drawn into the colon (1), assuming we’re IBS free, we won’t necessarily notice any change in abdominal symptoms or bowel habits. However, someone diagnosed with IBS may be particularly sensitive to this distension/fermentation and may find he/she experiences pain and altered bathroom habits. To give you an insight into what this feels like, try training after eating a heap of garlic, onions or beans (high FODMAP containing foods) – it’s likely you will experience some of these symptoms.

How do we manage IBS through diet?
We now know that high FODMAP containing foods contribute to IBS.
As such, the low FODMAP diet was devised by pioneering researchers at Monash University to reduce the symptoms of IBS in sufferers – the low FODMAP diet is typically the first option for the treatment of IBS. While it may not work for everyone, a higher proportion will achieve some symptom relief (3).

Food sources of FODMAPs
To give you a better understanding of FODMAPs, the particular carbohydrate culprits that must be reduced in the diet to manage IBS include:

  • Lactose – found in milk and yoghurt
  • Fructose – found in fruit such as apples, mangoes and watermelon
  • Fructans – found in bread, pasta, noodles, garlic and onion
  • Galacto-oligosaccharides (GOS) – found in kidney beans and baked beans
  • Polyols – sugar alcohols, ending in –ol, e.g. additives such as sorbitol

NB: It is important to note that it isn’t all foods in certain food groups (e.g. fruit) that need to be excluded – just the high FODMAP options.

To make it easier to know which foods are low FODMAP and which foods aren’t, researchers at Monash University have developed an App [The Monash University FODMAP diet APP], which lists most major foods along with a traffic light system to help you choose correctly. The APP also has recipes ideas, shopping lists and general FODMAP information, plus it’s continuously updated. At the time of writing, the cost to purchase the APP is $9.50 on Google Play Store or $12.99 if you are using a high FODMAP phone (sorry, Dad joke).

It is important to note that IBS sufferers can consume certain groups of FODMAP containing foods, and this is investigated through a food challenge process to allow re-introduction – the last thing we want to do is avoid foods for no reason. It is also important to note that while people following a low FODMAP diet often choose gluten-free options to avoid wheat products, this isn’t because we are looking to limit gluten. Wheat is a significant contributor to Fructan containing foods, so it is easier to opt for gluten-free options. To clarify: gluten is a protein found in wheat, barley, rye and triticale, while FODMAPs are carbohydrates. There is no reliable evidence to suggest avoidance of gluten-containing foods is beneficial to anyone other than those diagnosed with coeliac disease.

Abdominal pain: High FODMAP containing foods may cause intestinal discomfort in IBS sufferers.



Okay so we’ve covered FODMAPS and IBS, but what does this have to do with triathlon, Pete?

A recent case study found that those with particular gastrointestinal (GI) issues (not IBS) may also benefit from following a low FODMAP diet in the lead-up to an event. Researchers in Dr Kitic’s lab within the University of Tasmania trialled a recreational triathlete on a low FODMAP diet (7.2g FODMAP) compared to his regular diet (81g FODMAP, which is high FODMAP) for six days each (4). They found that during the low FODMAP diet there were no GI symptoms at all (4), whereas on his regular diet GI symptoms ranged from none to moderate. While we can’t take this as a blanket recommendation for all athletes who have GI disturbances, it warrants further investigation and could be a possible solution to reducing unwanted GI symptoms. We expect to see a lot more research in this area in coming years, so watch this space. Interestingly, in another survey, Lis and colleagues found that 86.5% of athletes who reported a high FODMAP trigger of GI symptoms eliminated lactose from their diet to reduce gastrointestinal distress (5), with the next highest FODMAP eliminated being GOS and fructose (~23% of athletes) (5). Again the old adage of association doesn’t mean causation, but it is interesting to note athletes perceiving symptom relief by removing these high FODMAP foods.

The idea of low FODMAPs in triathlon isn’t dissimilar from another fibre based diet option that some sports dietitians recommend leading up to an event – the low fibre or low-residue diet. The idea behind this is to empty the gut over one to four days (similar to an early colonoscopy diet for those out there old enough to know what that is). By going with low-fibre options such as white bread, pasta and rice instead of whole grain varieties; by cutting and removing skins from vegetables and fruit, we can reduce the contents of your bowels. Anecdotally, this facilitates a feeling of lightness in the stomach, and personally, it’s nice feeling light going into a triathlon (yes, I have completed one Olympic Distance tri).
This process will shed a certain amount of weight, although this is likely to be less than one kilogram, and individual results will vary. The downside of this approach is that it may reduce satiety (the feeling of fullness) in the lead up to an event, which could result in the over-consumption of pre-event nutrition (6). The low-fibre diet is a technique used largely for making weight in combat sports, where every gram is important, but it’s one worth considering if you are 100 per cent confident that all other nutritional aspects of your triathlon training and racing are covered.

FODMAP Culprits: Mango, pasta, milk and kidney beans are some of the carbohydrates that must be reduced to manage Irritable bowel syndrome, or IBS.



A quick note on gut health
In a previous edition of Australian Triathlete magazine, we had a great article on gut health [volume 25.1]. As such, it is timely to remind readers that a low FODMAP diet and, a low residue diet, in particular, can be low in prebiotics (foods that feed the gut bacteria). So, while these diets may be followed (IBS sufferers withstanding) for a short time to reduce GI symptoms, I wouldn’t suggest them as a long-term strategy without appropriate planning – the present consensus is to consume a variety of pre-biotic foods to fuel our healthy gut bacteria.

In summary

  • IBS is a real condition and can confer some uncomfortable and debilitating issues such as abdominal pain, flatulence and diarrhoea/constipation.
  • For those out there who are experiencing these symptoms, your first call would be a discussion with your GP.
  • A low FODMAP diet will offer most IBS sufferers some relief in symptoms.
  • There is early evidence that reducing FODMAPS may reduce GI symptoms in some exercising individuals, which is particularly relevant during peak competition.
  • A low residue diet may also be beneficial in the lead up to a major event, though only likely to make an actual performance benefit on a very hilly course.
  • The use of these diet-manipulation strategies long term without adequate planning is not conducive to good gut health. If you don’t have any GI symptoms during events, then low FODMAP isn’t something that would benefit you (from current understanding).
  • Before trialling any of these diet options, please talk it over with your sports dietitian, as ensuring adequate fuelling pre-event needs to be your priority.
  • If you do suffer GI symptoms, don’t neglect the fact that we can train the gut to get used to nutrition during exercise
  • Always practice in training what you want to achieve during the race.
    Happy eating!



1. Shepherd S. Food intolerance management plan / Sue Shepherd & Peter Gibson; food photography by Mark O’Meara. Gibson PR, O’Meara M, editors. Camberwell, Vic: Penguin; 2011.
2. Topping DL, Clifton PM. Short-chain fatty acids and human colonic function: roles of resistant starch and nonstarch polysaccharides. (0031-9333 (Print)).
3. Staudacher HM, Whelan K, Irving PM, Lomer MC. Comparison of symptom response following advice for a diet low in fermentable carbohydrates (FODMAPs) versus standard dietary advice in patients with irritable bowel syndrome. Journal of human nutrition and dietetics: the official journal of the British Dietetic Association. 2011;24(5):487-95.
4. Lis D, Ahuja KDK, Stellingwerff T, Kitic CM, Fell J. Case Study: Utilizing a Low FODMAP Diet to Combat Exercise-Induced Gastrointestinal Symptoms. International journal of sport nutrition and exercise metabolism. 2016;26(5):481-7.
5. Lis D, Ahuja KDK, Stellingwerff T, Kitic CM, Fell J. Food avoidance in athletes: FODMAP foods on the list. Applied Physiology, Nutrition, and Metabolism. 2016;41(9):1002-4.
6. Reale R, Slater G, Burke LM. Individualised dietary strategies for Olympic combat sports: Acute weight loss, recovery and competition nutrition. European Journal of Sport Science. 2017;17(6):727-40.


Peter Herzig

Centred Nutrition was founded by Peter Herzig (APD). Peter is a qualified Dietitian and Accredited Sports Dietitian who also has a degree in Exercise Science. Peter set up Centred Nutrition in Brisbane and the Sunshine Coast to focus on a client centred approach; as there is no one solution in nutrition that will work for everyone.

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