Is Onion Low FODMAP?
No. Onion is high in FODMAPs, and it is one of the most common IBS triggers.
Main FODMAPs: Fructans
Why
Onions are rich in fructans, a carbohydrate that is poorly absorbed in the small intestine and fermented by gut bacteria. That fermentation can cause gas, bloating, and pain. All common types, including white, yellow, red, and shallots, are high, and cooking does not remove the fructans.
Good to know
- Onion powder, dried onion, and onion salt are just as high, and they are in many stocks, sauces, and seasoning blends.
- The fructans stay in the food, not the oil, so frying onion and then removing it still leaves some behind in the dish.
- The green tops of spring onions (scallions) and chives are generally much easier to tolerate than the white bulb.
Low FODMAP swaps
- Green tops of spring onions or chives for fresh onion flavor
- Garlic-infused or onion-infused oil, where the fructans stay out of the oil
- A pinch of asafoetida (hing) fried in oil; check that it is not mixed with wheat flour
Related foods
Related reading
- Is Garlic Low FODMAP? Garlic, Onion, and What to Use Instead
- How to Read a Food Label for Hidden FODMAPs
Good to know: FODMAP content varies with variety, ripeness, preparation, brand, and serving size, and everyone's tolerance is different. This page gives general guidance without exact serving thresholds. For tested serving sizes, check the Monash University FODMAP Diet app and talk to your dietitian.
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