What quercetin is
Quercetin is a flavonoid, a yellow plant pigment found in onions, apples, capers and many berries. Food supplies it in small amounts, usually a few milligrams to tens of milligrams a day, while supplements deliver it in a single capsule. It is sold in different forms: quercetin dihydrate, which is the pure compound with two molecules of water, and complexes in which quercetin is combined with other ingredients.
What the EU allows us to say
No health claim for quercetin has been authorised in the EU, and the EU Register of nutrition and health claims contains no approved wording for it, so we make no statement about what it does in the body. The only authorised claims on this page belong to the vitamin C in the Solgar complex, under Regulation (EU) No 432/2012:
- Vitamin C contributes to the normal function of the immune system.
- Vitamin C contributes to the protection of cells from oxidative stress.
- Vitamin C contributes to the reduction of tiredness and fatigue.
These apply to the vitamin, which is present at 500 mg (625% of the nutrient reference value) per daily portion. They do not extend to the quercetin, bromelain or bioflavonoids in the same capsule.
Quercetin products in this category
| Product | Form | Quercetin per daily portion | Other ingredients per daily portion | Label dose |
|---|---|---|---|---|
| OstroVit Quercetin Dihydrate, 75 mg | vegan capsule | 75 mg | none | 1 capsule |
| Solgar Quercetin Complex with Ester-C | capsule | 500 mg | 500 mg vitamin C as Ester-C (625% NRV), 50 mg calcium, 50 mg bromelain, citrus bioflavonoid complex | 2 capsules |
Single compound or complex
The OstroVit capsule contains only quercetin, so you see exactly what you are paying for and the price per day is low. The Solgar complex has more than six times as much quercetin and adds vitamin C in the Ester-C form, which is calcium ascorbate, together with bromelain and citrus bioflavonoids. If you already take vitamin C, add up the total from both products, and check the amount against the immune support overview.
Warnings on the labels
The OstroVit label says not for children, pregnant or breastfeeding women. The Solgar label asks pregnant and breastfeeding women, people who take medicines and people with a medical condition to consult a doctor first, and to stop use if adverse effects occur. Bromelain is an enzyme from pineapple, so people with a pineapple allergy should avoid the complex.
Related pages
Zinc and vitamin D also have authorised claims about the immune system and are gathered on the zinc and vitamin D pages. Elderberry is described on the elderberry page.
Frequently asked questions
Does quercetin have an authorised health claim?
No. The EU has not authorised a claim for quercetin, so no quercetin product may promise anything about health.
How much quercetin is in the products here?
75 mg in one OstroVit capsule and 500 mg in the two capsules of the Solgar complex. The EU sets no reference value for quercetin.
Is quercetin the same as vitamin C?
No. Vitamin C is a vitamin with an official reference value and authorised claims. Quercetin is a plant flavonoid with neither.
Can I take quercetin with zinc?
Many people do, and some combine them in separate products. Count the zinc from every product and keep to each label dose.
Which one should I choose?
Choose OstroVit if you want quercetin alone at a lower dose. Choose Solgar if you want the combination and are comfortable with the added vitamin C, calcium and bromelain.
Sources
- Regulation (EU) No 432/2012 (authorised health claims)
- EU Register of nutrition and health claims
- NIH Office of Dietary Supplements: Vitamin C
- EFSA: Health claims
Content reviewed by Inese Kalniņa, dietitian.
2026-07-25