Onion (Spanish/red, raw)
Vegetables · Alliums
Raw red onion, listed as Spanish/red onion in Monash's app, is low FODMAP at 10 g. The app shows 13 g as moderate and 75 g as high because of fructans. This is a small garnish-sized allowance for this specific entry, not a rating for an unrestricted serving of onion.
Serving sizes for onion (spanish/red, raw)
Use grams for raw red onion. The app's ring descriptions are approximate; both the 10 g and 13 g entries can be described as one ring.
Tested serving sizes
| Serving | Amount | Main FODMAP | Rating |
|---|---|---|---|
| 1/2 medium onion | 75 g | Fructans 0.58 g | |
| 10 g portion | 10 g | Fructans 0.08 g | |
| 13 g portion | 13 g | Fructans 0.1 g |
Breakdown for 0.5 medium onions
Is onion (spanish/red, raw) low FODMAP?
Fructans are amber at 13 g and red at 75 g in the raw red-onion entry. Its 10 g green portion is more specific than the site's older combined onion entry, which groups several varieties together. For red onion, use this variety-specific guide rather than treating the combined entry as evidence that all onion varieties have the same limit.
Onion (Spanish/red, raw) and IBS: what to know
The listed low and moderate red-onion amounts are close together, making a scale more useful than an estimated ring or spoonful. That difference describes the tested food, not an exact personal symptom boundary. When tracking a meal, include red onion in salsa or a dressing as well as the slices visible on top.
Gut-friendly ways to eat onion (spanish/red, raw)
Weigh the red onion after removing the peel, then slice or dice your portion for a garnish. Spread a small amount through a salad to distribute the flavour. If a recipe needs a larger volume of allium garnish, compare chives or spring onion green tops using their own guides. Pickled red onion requires preparation-specific information.
Frequently asked questions
How much raw red onion is low FODMAP?
Monash lists 10 g green, 13 g amber and 75 g red for Spanish/red onion, raw. Weigh the edible portion rather than assuming every onion ring has the same weight.
Why does the general onion page give different advice?
The general onion entry combines brown, white and red onions in older catalogue data. This separately verified raw red-onion entry provides the more specific 10 g green portion.
Does the 10 g portion apply to pickled red onion?
This check covered raw red onion only. Pickling is a different preparation, so neither this 10 g value nor a different pickled-onion entry establishes a tested allowance for every jar or homemade pickle.
Is Vidalia onion the same as red onion?
No. The raw Vidalia onion guide has a different verified green portion of 22 g. Use the variety you actually have rather than substituting its FODMAP allowance.
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Sources and editorial notes
- Monash University FODMAP Diet App
App entry checked directly on 27 September 2026: Onion, Spanish / red, raw. Supports the listed portion weights, traffic-light ratings and FODMAP groups. The exact compound quantities shown in the catalogue breakdown were not verified by this app check.