Quercetin 500 features 500 mg of quercetin in one capsule to promote a healthy immune response, support cardiovascular and endothelial health, and support antioxidant status.* Why quercetin? Quercetin is one of the most studied dietary flavonoids and is often found in a variety of plant foods including fruits, vegetables, and tea. Although a lot of foods contain quercetin, the daily intake of quercetin for a person following a typical Western diet is estimated to be between 0 and 30 mg per day. However, research shows that the immune and cardiovascular benefits of quercetin are reached at supplemental intakes of 500 mg to 1,000 mg per day.