Onion
The flavour base of most cuisines, with quercetin and prebiotic fructans.
Nutrition per 100 g
Standardised to 100 g of onion, raw for fair comparison. Typical serving: 1 medium onion, raw (110 g) — 44 kcal per 110 g serving.
| Nutrient | Per 100 g | Per serving (110 g) | Per 100 kcal |
|---|---|---|---|
| Energy | 40 kcal | 44 kcal | 100 kcal |
| Protein | 1.1 g | 1.2 g | 2.7 g |
| Carbohydrate | 9.4 g | 10.3 g | 23.4 g |
| Fat | 0.1 g | 0.1 g | 0.2 g |
| Fibre | 1.7 g | 1.9 g | 4.3 g |
Figures are typical values and vary with variety, preparation and brand.
Micronutrients
Vitamins and minerals per 100 g of onion, with a typical serving and FDA Daily Value for adults.
| Nutrient | Per 100 g | Per serving (110 g) | % DV |
|---|---|---|---|
| Vitamins | |||
| Vitamin C | 8.1 mg | 8.9 mg | 9% |
| Minerals | |||
| Calcium | 17 mg | 18.7 mg | 1% |
| Iron | 0.24 mg | 0.26 mg | 1% |
| Magnesium | 11.4 mg | 12.5 mg | 3% |
| Phosphorus | 41 mg | 45.1 mg | 3% |
| Potassium | 197 mg | 217 mg | 4% |
| Sodium | 1 mg | 1.1 mg | <1% |
| Zinc | 0.17 mg | 0.19 mg | 2% |
| Selenium | 0.5 µg | 0.55 µg | <1% |
| Copper | 0.058 mg | 0.064 mg | 6% |
| Manganese | 0.12 mg | 0.13 mg | 5% |
| Iodine | 0 µg | 0 µg | 0% |
Source: USDA FoodData Central — Onions, red, raw
% DV uses FDA Daily Values for adults. Nutrients that USDA does not report for this entry are omitted. Values vary with variety, preparation and brand.
Why eat onion?
- Adds depth so meals need less salt and fat to taste good.
- Fructans act as prebiotics for gut bacteria.
- Red onions are particularly high in quercetin.
How to include it
- Cook slowly in oil for 20 minutes to build a sweet base.
- Quick-pickle red onion in vinegar for salads and tacos.
- Roast wedges whole alongside a tray bake.
Things to consider
- One of the strongest FODMAP triggers for people with IBS.
- Raw onion is much harsher than slow-cooked.
Educational content. This article is for general information and is not medical advice. Speak to a qualified health professional about your individual circumstances.
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