What is FODMAP?
Why FODMAPs cause symptoms
FODMAPs share two properties that make them hard on a sensitive gut: they draw extra water into the small intestine, and they're rapidly fermented by bacteria once they reach the large intestine. In most people this passes unnoticed. In people with irritable bowel syndrome (IBS), the resulting stretching and gas production trigger real symptoms — bloating, cramping, wind, and altered bowel habits.
The six FODMAP subtypes
"FODMAP" isn't one thing — it's an umbrella term for six different types of carbohydrate, each found in different foods:
- Fructans — wheat, rye, onion, garlic, and some vegetables
- GOS (galacto-oligosaccharides) — legumes, chickpeas, lentils
- Sorbitol — a polyol in stone fruits and some sweeteners
- Mannitol — a polyol in mushrooms, cauliflower, and some sweeteners
- Excess fructose — honey, apples, and some fruits in large amounts
- Lactose — milk and some dairy products
This matters because most people with IBS react to only one or two subtypes, not all six. That's why DietTribe's product filter lets you pick specific subtypes to avoid, rather than forcing an all-or-nothing "low FODMAP" toggle.
The diet is a process, not a permanent diet
The low FODMAP diet as researched and popularised by Monash University is designed to run in three phases:
- Elimination — cut out high-FODMAP foods across all six subtypes for a short period (typically 2–6 weeks) to establish a symptom baseline.
- Reintroduction — systematically reintroduce one subtype at a time to identify which specific ones trigger symptoms.
- Personalisation — build a long-term diet that only restricts the subtypes that actually affect you, keeping everything else on the table.
Staying in strict elimination indefinitely is not the goal, and isn't recommended — it can restrict a wide range of otherwise healthy foods unnecessarily. See our guide to the FODMAP diet for IBS for how this plays out in practice.
Where to go for exact food ratings
For precise, lab-tested FODMAP content of specific foods, the Monash University FODMAP food guide (also available as a paid app) is the reference dietitians use worldwide. Our low FODMAP food list guide is a starting point organised by food group — not a substitute for it.
Frequently asked questions
What does FODMAP stand for?
Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols — a group of short-chain carbohydrates found in a wide range of everyday foods, from wheat and onions to apples and milk.
What is the low FODMAP diet?
A structured, short-term elimination and reintroduction process used to identify which specific FODMAP subtypes trigger a person's IBS symptoms — not a permanent way of eating. It is typically followed for a few weeks under dietitian guidance, then foods are reintroduced one subtype at a time.
Is FODMAP the same as gluten intolerance?
No. Gluten is a protein; FODMAPs are carbohydrates, and wheat is high in both. Some people who feel better avoiding wheat are actually reacting to its fructans (a FODMAP), not gluten — which is why cutting out wheat can improve IBS symptoms even in people who don't have coeliac disease or genuine gluten sensitivity.
Do I need to avoid all six FODMAP subtypes?
Almost never. Most people with IBS are sensitive to only one or two of the six subtypes (fructans, GOS, sorbitol, mannitol, excess fructose, and lactose) — which is exactly what the reintroduction phase of the diet is designed to identify.