Quercetin
A plant antioxidant found in onions and apples. Standard capsules barely absorb.
Quercetin is a flavonoid antioxidant found in onions, apples, and capers, studied for its antioxidant and anti-inflammatory effects. Like curcumin, its biggest limitation is absorption: quercetin dihydrate, the standard, cheapest supplement form, is poorly absorbed on its own. Phytosome formulations, sold under names such as Quercefit, wrap the compound in a delivery system that measurably improves how much reaches the bloodstream. Quercetin combined with bromelain is another common pairing, though the bromelain addition is more about digestive support than improving quercetin's own absorption.
Reference values
Daily reference values from official nutrition authorities. These are population reference figures, not personal recommendations.
| RDA | Upper limit | Source |
|---|---|---|
| 500 mg | 1000 mg | UK |
Forms and bioavailability
Not all forms are absorbed equally. The form on your supplement label affects how much your body can actually use.
| Form | Absorption | With food | Timing | Evidence |
|---|---|---|---|---|
| quercetin phytosome (Quercefit) | Higher | Either | Either | Likely |
| quercetin dihydrate | Lower | Either | Either | Possible |
| quercetin with bromelain | Lower | Either | Either | Possible |
Stack Almanac tracks which quercetin form you're taking, since a phytosome product and a plain dihydrate capsule are not delivering comparable amounts at the same milligram dose.
Track your Quercetin in Stack Almanac
Last reviewed: 2026-07-08. Reference values are adult-general RDAs from UK. Individual needs may vary. This page is for informational purposes only and is not a substitute for professional medical advice.