Quercetin
Quercetin is a plant flavonoid found in foods such as onions and apples.
Also listed as Quercetin Phytosome, Sophora Japonica, Quercetin Extract, Apple extract
What it is studied for
The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.
What is quercetin?
Quercetin is a plant flavonoid found in foods such as onions and apples. Laboratory studies show antioxidant activity and inhibition of histamine release; these mechanisms do not establish allergy treatment in people. 1
Key studies
The most recent publications linked to Quercetin's ratings.
Why people take it
SuppCo community snapshot, 2026-09-28. Reasons for use are not evidence that it works.
Questions people ask
Can it replace blood-pressure medication?
The reviews evaluate modest blood-pressure changes, not equivalence to prescribed treatment. 2
Is it a proven antihistamine?
Histamine inhibition in laboratory experiments is not proof of clinical allergy relief. 1
Are food amounts similar to capsules?
The German safety review distinguishes ordinary dietary exposure from much higher supplement doses. 3
Related nutrients
Catechin
MyricetinSources
- Quercetin Memorial Sloan Kettering Cancer Center
- Safety Aspects of the Use of Quercetin as a Dietary Supplement Molecular Nutrition & Food Research, 2018
