Onions are alliums that provide quercetin, sulphur compounds and prebiotic fibres such as inulin, which feed gut bacteria. They are low in calories and add flavour with few drawbacks.
Boil briefly in a small amount of water; folate and quercetin can leach into the liquid, so use it in the dish where possible.
Where Onions, boiled in unsalted water Stands Out
Macronutrients per 100g
Vitamins & Minerals
| Nutrient | Per 100g | % Daily Value* | Level |
|---|---|---|---|
| Potassium | 105 mg | 5% | |
| Chloride | 49.0 mg | 6% | |
| Calcium | 25.0 mg | 3% | |
| Phosphorus | 23.0 mg | 3% | |
| Folate | 8.00 µg | 4% | |
| Magnesium | 7.00 mg | 2% | |
| Vitamin C | 4.00 mg | 5% | |
| Vitamin A (RE) | 1.00 µg | 0% | |
| Niacin equivalents (NE) | 0.500 mg | 3% | |
| Vitamin E (alpha-TE) | 0.310 mg | 3% | |
| Niacin (B3) | 0.300 mg | 2% | |
| Iron | 0.290 mg | 2% | |
| Zinc | 0.200 mg | 2% | |
| Manganese | 0.110 mg | 6% | |
| Vitamin B6 | 0.070 mg | 5% | |
| Pantothenic Acid (B5) | 0.060 mg | 1% | |
| Copper | 0.050 mg | 5% | |
| Thiamin (B1) | 0.030 mg | 3% | |
| Riboflavin (B2) | 0.000 mg | 0% | |
| Selenium | 0.000 µg | 0% | |
| Vitamin B12 | 0.000 µg | 0% | |
| Vitamin D | 0.000 µg | 0% | |
| Iodine | 2.00 µg | 1% | |
| Polyunsaturated fat (PUFA) | 0.140 g | — | |
| Trans fat | 0.000 g | — | |
| Glucose (dextrose) | 1.60 g | — | |
| Sucrose | 1.40 g | — | |
| Fructose | 1.20 g | — | |
| Maltose | 0.000 g | — | |
| Cholesterol | 0.000 mg | — | |
| Beta-carotene | 5.00 µg | — | |
| Biotin (Vitamin B7) | 0.700 µg | 1% | |
| Retinol (vitamin A) | 0.000 µg | 0% |
* % Daily Value is the proportion of an adult
EU Nutrient Reference Value (NRV) supplied by 100g of this food.
NRVs are the labelling standard — the same basis as the “%RI” figures printed on
food packaging — so these percentages are directly comparable with a shop label.
They are a single adult figure and do not vary by age or sex, which is why they
sometimes differ from UK dietary reference values: the NRV for vitamin C is 80mg
where the UK RNI is 40mg. When Nutriofia assesses your own intake in the
reports and trackers, it uses the age- and sex-specific UK values instead.
Fibre is shown without a percentage. Our fibre values use the UK
Englyst NSP method, while the published 30g daily goal is an AOAC figure — the two
are measured differently and a single percentage would mislead.
How we source and normalise our data →
Phytochemicals
Bioactive plant compounds — not classified as essential nutrients but associated with a range of health benefits.