Quercetin is a highly potent bioflavonoid found in a variety of foods. It also serves as a building block for flavonoids. It is found in many foods, such as onions (especially red onions), apples, tea, nuts, various types of berries, cauliflower, and cabbage. Quercetin possesses powerful antioxidant properties, like other bioflavonoids, and has the ability to stabilize cell membranes. These benefits contribute to the proper functioning of the bodys defense mechanisms. In addition, quercetin has significant anti-inflammatory action, due to the direct inhibition of several initial processes of inflammation. For example, it inhibits both the production and release of histamine and other allergic/inflammatory mediators. According to research studies, it may have positive effects on allergies/inflammation and respiratory diseases, such as bronchitis and asthma. Note: The product contains quercetin dihydrate. It is recommended to take vitamin C for optimal activity.