Quercetin is a naturally accounting bioflavonoid found in high concentrations in red wine, onions and green tea. Quercetin possesses powerful antioxidant properties and like other bioflavonoids, has the ability to stabilize cell membranes. These qualities contribute to Quercetin's ability to support healthy histamine levels and balanced immune function. In addition, clinical studies have demonstrated that Quercetin may support prostate health.