Key takeaways
- All onion varieties (white, brown, red, shallot, leek bulb) are high FODMAP — fructans accumulate even in small amounts.
- Onion powder is even more concentrated and should be treated as strictly high FODMAP.
- The green tops (leaves) of spring onions are low FODMAP and can be used freely.
- Like garlic, onion fructans are water-soluble — they transfer into stocks and soups, making those broths high FODMAP.
Onion is one of the two most problematic FODMAP foods in everyday cooking — the other being garlic. Both are fructan-heavy, both appear in almost every savoury recipe, and both can cause significant symptoms in even tiny amounts for fructan-sensitive IBS patients.
FODMAP status at a glance
- —Brown / yellow onion: high FODMAP at any amount
- —White onion: high FODMAP
- —Red onion: high FODMAP
- —Shallot: high FODMAP
- —Leek bulb (white part): high FODMAP
- —Spring onion / scallion — green tops only: low FODMAP
- —Chives: low FODMAP
The stock problem
Low-FODMAP onion alternatives
- —Spring onion green tops — use freely; slice and add at the end of cooking
- —Chives — mild onion flavour, low FODMAP, great raw
- —Garlic-infused oil — replaces both onion and garlic depth in fried bases
- —Asafoetida (hing) — a small pinch in hot oil gives an allium note
Re-introduction: after the strict elimination phase, onion is typically one of the harder foods to re-introduce. Start with a very small amount (a few rings) as a controlled test meal, and note symptoms over the following 24 hours.
References
- 1.
- 2.Shepherd SJ, Gibson PR — Fructose malabsorption and symptoms of IBS — Clinical Gastroenterology and Hepatology, 2006
