Quercetin fisetin supplements is a naturally occurring flavonoid found in many foods, including apples, onions, tea leaves and red wine. Quercetin dihydrate is the most common form of quercetin. The name comes from the Latin word for oak because it was first isolated from oak bark. It has antioxidant properties and helps protect cells against damage caused by free radicals.* Antioxidants are important for supporting overall health, as they help neutralize free radicals that can cause damage to cells in the body.* Quercetin is a powerful antioxidant flavonoid that can help to support immune function, cardiovascular health, and kidney support.* It is one of the most abundant dietary flavonoids in onions with other sources including tea leaves, apples, berries, grapes and red wine. Quercetin also has potent anti-inflammatory properties which makes it useful for supporting respiratory health as well.* This quercetin dihydrate, or quercetin supplement, is available in powder and gelatin capsule form. Each serving contains 500 mg quercetin and does not contain any fillers and additives. In addition, the capsules comes in 100 & 300 counts.