The Low FODMAP Diet

A dietitian-guided approach for IBS symptoms

What are FODMAPs?

FODMAPs are a group of small sugars and fibres found in many everyday foods that are poorly absorbed in the small intestine. In sensitive people they draw water into the gut and are fermented by bowel bacteria, producing gas — leading to bloating, pain, wind and altered bowel habit. FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols.

The low FODMAP diet was developed at Monash University here in Australia and improves symptoms in about 3 out of 4 people with IBS.

Examples of high and low FODMAP foods

• Higher FODMAP: onion, garlic, wheat-based bread and pasta (in larger amounts), legumes, apples, pears, mango, watermelon, honey, milk and soft cheeses, cauliflower, mushrooms, sugar-free gums/mints (polyols)

• Lower FODMAP: rice, oats, quinoa, sourdough spelt bread, potatoes, carrots, zucchini, green beans, spinach, tomatoes, bananas (firm), oranges, strawberries, grapes, lactose-free milk, hard cheeses, plain meats, fish, eggs, tofu, garlic-infused oil

Portion size matters — many foods are low FODMAP in small serves. The Monash University FODMAP Diet app is the most reliable, up-to-date guide and we strongly recommend it.

The three phases — this is not a forever diet

• Phase 1 — Elimination (2–6 weeks): replace high FODMAP foods with low FODMAP alternatives to settle symptoms.

• Phase 2 — Reintroduction (6–8 weeks): systematically re-test each FODMAP group to identify which ones trigger your symptoms and in what amount. Most people tolerate several groups well.

• Phase 3 — Personalisation (long term): return to the most varied diet your gut allows, restricting only your proven triggers.

Staying strictly low FODMAP long term is unnecessary and not recommended — it restricts foods that feed healthy gut bacteria and makes eating socially difficult.

Important practical points

• Work with an accredited practising dietitian — guided patients get much better results and maintain better nutrition

• Do not start the diet before coeliac testing — you must be eating gluten-containing wheat for coeliac tests to be accurate

• The diet is not designed for weight loss and needs care in pregnancy, in children, or if you have a history of disordered eating — tell us if any of these apply

• If there is no improvement after 4–6 weeks of doing it well, the diet is unlikely to be your answer — other effective IBS treatments exist

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This information is general and not a substitute for personalised medical advice. Please discuss any questions with your gastroenterologist or GP. If you develop severe symptoms, call 000 or go to your nearest emergency department.