Understanding FODMAPs - The Role of the Low FODMAP Diet in IBS Symptom Management

Understanding FODMAPs - The Role of the Low FODMAP Diet in IBS Symptom Management

Written by Lisa Kunstler, FodShop Nutritionist and Group Fitness Instructor

An Introduction to FODMAPs 

The term 'FODMAP' is an acronym which stands for:







These works may sound like a barrage, however they can be broken down (pardon the pun!) in to simpler components. 

Let's go back to basics!

Carbohydrates are molecules found naturally in a variety of foods we eat daily, including wheat, pasta, legumes, rye, grains and in fruits & some vegetables. (1) 

FODMAPs are types of carbohydrates; short-chain in nature, and often poorly absorbed by the intestine, resulting in the attraction of excess water, causing bloating and diarrhoea as a result. (1) 

Once these malabsorbed sugars pass into the large intestine they are then quickly fermented by bacteria living there, producing gas, which consequently causes abdominal pain, discomfort and further bloating. (1) 

Humans, in general, lack the enzymes required to digest certain FODMAPs (we will get to these in the next section!). However, for those with Irritable Bowel Syndrome (IBS), a phenomenon called 'visceral hypersensitivity' explains why some people suffer from such horrid symptoms, while others do not. (1) 

Breaking Down FODMAPs

FODMAPs can be broken down into more specific names, including fructans, galacto-oligosaccharides (GOS), fructose in excess of glucose, lactose and polyols. (2)

The FODMAP acronym is explained in more detail below:

Fermentation - Occurs in the gut when the FODMAP-loving bacteria consume the short-chain carbohydrates, causing IBS symptoms.

Oligosaccharides - 'fructans' and 'GOS' to name a few, which are malabsorbed in the gut due to the lack of the fructan and GOS-degrading enzymes in humans. They are highly fermentable by the gut bacteria, causing gas production, abdominal pain and bloating in IBS. (3)

Dissacharides - 'Lactose' which is poorly digested in people lacking the lactose dissolving enzyme, 'lactase'. This is common in Asian and Mediterranean backgrounds, and in diseases causing intestinal inflammation (such as Crohn's disease), with prevalence increasing with age. (3)

Most people are able to digest lactose and will not need to follow the lactose component of the low FODMAP diet. (3) If you are unsure as to whether or not this applies to you, please visit your GP or Accredited Practising Dietitian (Australia) or Registered Dietitian (NZ, Canada & USA)

Monosaccharide represent 'fructose', the smallest FODMAP carbohydrate. When fructose is present in greater quantities than glucose in the gut, an osmotic imbalance occurs in the gut, enabling ready attraction of water into the intestine, causing pain, bloating, diarrhoea and altered transit through the gut. (3) 


Polyols commonly include 'mannitol', 'xylitol' and 'sorbitol' many of which are considered artificial sweeteners and are commonly found in 'sugar-free' chewing gum, baked goods and confectionary. Polyols are sugar alcohols and behave similarly to fructose in the gut, causing the same osmotic effects as those experienced with fructose in excess. (3)

Some examples of foods high in each FODMAP group are provided below.

  • Polyols: avocado, button mushrooms, green apples, apricot, blackberries
  • Fructose: watermelon, mango, asparagus, peaches, plums, nectarines, honey
  • Fructans: onion, garlic, ripe banana, figs, multigrain and rye bread, wheat based gnocchi
  • Lactose: cow's milk, natural Greek yoghurt, vanilla ice cream (2 scoops)
  • GOS: cashews, pistachios, soy protein, silken tofu, red kidney beans, pinto beans, falafel

Some examples of foods low in FODMAPs are provided below.

  • Vegetables: cucumber, iceberg lettuce, oyster mushrooms, olives, spring onion (green tops only), unpeeled potato, jap pumpkin, radish
  • Fruits: navel oranges, starfruit, raspberries (under 30), 2 small green kiwis, 6 grapes, clementine, 1 medium firm banana
  • Grains: unprocessed bran, gluten free bread, rolled oats, spelt sourdough, 1 slice white bread, gluten free flour, gluten free pasta, quinoa, brown and white rice
  • Lean meat/alternatives: tempeh, 1 cup firm tofu, egg replacer, 1/4 cup rinsed canned chickpeas and beans*, brazil nuts, chestnuts, macadamia, peanuts, pine nuts, chia seeds, hemp seeds, sesame seeds
  • Dairy: lactose free milk, butter, cheddar, feta, parmesan, nut milk, lactose free yoghurt

*Rinsing legumes prior to consumption helps to wash out the FODMAPs as they are water soluble.

For more information on what foods are high and low in FODMAPs, visit the Monash University FODMAP Diet app, designed for the low FODMAP diet. 

The Role of the Low FODMAP Diet in IBS Symptom Management

Who suffers with IBS symptoms?

Up to 15% of the Western population suffer from IBS, with at least 5 annual visits to the doctor predicted for these individuals. (3) A diet high in FODMAPs has been found to increase symptoms of excessive flatulence, abdominal cramping, constipation, bloating and diarrhoea in a person suffering with IBS. (3)

Note that these symptoms can also present in Coeliac's Disease, some cancers of the colon, Inflammatory Bowel Diseases (Crohn's and Colitis), Endometriosis and others.

It is vital that a proper diagnosis is made to ensure an appropriate form of therapy followes. (3) Please contact an Accredited Practising Dietitian (Australia) or Registered Dietitian (NZ, Canada & USA) to determine the best nutrition plan.

Does the Low FODMAP Diet Work?

The purpose of the low FODMAP diet is to relieve the symptoms associated with IBS.

Over the past 2 decades, several studies have investigated the efficacy of the diet low FODMAP diet in relieving IBS and IBS-type symptoms, with more recent research suggesting that the low FODMAP diet may provide symptom relief for up to 86% of patients. (4)

The diet is now internationally recognised as the accepted dietary management strategy for patients with IBS. (3) It has been successful in not only research settings, but also specialised clinics around the world. (3, 4)

I have been diagnosed with IBS, where-to from here?

The low FODMAP diet includes a 3-phase process including FODMAP elimination, reintroduction and then personalisation. Click HERE to view the 3-phase process in greater detail. 

Before attempting the diet, please contact an Accredited Practising Dietitian (Australia) or Registered Dietitian (NZ, Canada & USA), as such practitioners are experts in the implementation of the FODMAP diet. It is never recommended to attempt the diet without professional consultation, as this can lead to misdiagnosis or self-diagnosis of other conditions, harm to the intestinal microbiome and inappropriate management of your symptoms. (3) 

Most people will see improvements in their symptoms following the diet under the guidance of a dietitian. If not, the recommendation is to consider additional, or other dietary and non-dietary approaches based on your dietitian's recommendation. (3) 

Final Thoughts

The low FODMAP diet is an internationally recognised treatment plan for sufferers of IBS. The diet surrounds the concept of FODMAPs, short-chain carbohydrates that can be poorly absorbed in the gut and cause symptoms of bloating and gas production. Following a diet containing foods low in FODMAPs my relieve IBS symptoms and improve quality of life.

It is always important to contact your Accredited Practising Dietitian before you attempt the diet, in order to ensure your symptoms are managed effectively and safely. 


1. Shepherd, Susan J; Lomer, Miranda C E; Gibson, Peter R (2013). Short-Chain Carbohydrates and Functional Gastrointestinal Disorders. The American Journal of Gastroenterology, 108(5), 707–717. doi:10.1038/ajg.2013.96 

2. Gibson PR. History of the low FODMAP diet: History of the low FODMAP diet. J Gastroenterol Hepatol [Internet]. 2017;32 Suppl 1:5–7. Available from: http://dx.doi.org/10.1111/jgh.13685

3. Barrett JS. How to institute the low-FODMAP diet: How to institute the low-FODMAP diet. J Gastroenterol Hepatol [Internet]. 2017 [cited 2022 Mar 17];32 Suppl 1:8–10. Available from: https://pubmed.ncbi.nlm.nih.gov/28244669/

4. Nanayakkara WS, Skidmore PM, O'Brien L, Wilkinson TJ, & Gearry RB (2016). Efficacy of the low FODMAP diet for treating irritable bowel syndrome: the evidence to date. Clinical and experimental gastroenterology9, 131–142. Available from: https://doi.org/10.2147/CEG.S86798


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