Kal Quercetin is a non-citrus bioflavonoid. Bioflavonoids are intended to provide antioxidant activity to help fight free radicals and provide nutritive support to help maintain normal capillary permeability. The human body cannot manufacture bioflavonoids and therefore must receive its supply through supplementation or diet. KAL guarantees that NO ingredients other than those listed on this label have been added to this product.