Is onion low FODMAP?
No. White, red and brown onions, shallots and onion powder are high FODMAP because of fructans. The green tops of spring onions are low FODMAP.
Main FODMAP group: Fructans
Onion is, with garlic, the most common reason a “simple” meal causes symptoms. It is high in fructans, and it shows up in stocks, sauces, soups, salad dressings and seasoning mixes.
Which parts are low FODMAP?
The white bulb of onions, spring onions and leeks holds most of the fructans. The green tops of spring onions and leeks are much lower and are a standard low FODMAP swap. Like garlic, fructans from onion do not dissolve into oil, so onion-infused oil is a low FODMAP way to keep the flavor.
Cooking does not remove FODMAPs
Frying, roasting or caramelizing onion does not break down the fructans. Onion cooked into a sauce stays high FODMAP even if you pick out the pieces.
Watch for onion powder
Onion powder is concentrated and common in crisps, crackers, sausages and spice rubs. If your symptoms follow processed foods, onion powder is worth checking on the label.
Low FODMAP swaps
- The green tops of spring onions (scallions)
- The green leaves of leeks
- Chives
- Onion-infused oil