FODMAP checker
Onion
Onion is one of the highest-FODMAP foods and a very common IBS trigger. It contains fructans in large amounts. All forms — raw, cooked, powdered, and dried — should be avoided during the elimination phase.
Why is onion high FODMAP?
Like garlic, onion is very high in fructans. Even small amounts of onion — including onion powder — contain enough fructans to cause symptoms in people with IBS.
Cooking does not reduce the FODMAP content significantly. Onion pieces in soups or stews will leach fructans into the liquid, making the entire dish high FODMAP.
The green tops of spring onions (scallions) are the exception — only the green part is low FODMAP. The white bulb end is high FODMAP and must be discarded.
Tips & alternatives
- 🧅Spring onion (green tops only)Only the green part of spring onions is low FODMAP. Discard the white bulb end. Add to salads, soups, and stir-fries.
- 🫙Onion-infused oilSame principle as garlic-infused oil. Fry onion in oil, remove all pieces before eating. Gives the flavour without the fructans.
- 🌿ChivesLow FODMAP in standard serving sizes. Mild onion flavour, great as a garnish or in dressings.
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