Quercitin is a naturally occurring bioflavonoid found in fruits and vegetables such as kale, onion, tomatoes and berries. It is used in skincare for its antioxidant abilities, meaning it can neutralise free radicals before they cause any damage to the skin. Studies also show Quercetin to have anti-inflammatory effects, and an ability to protect the skin against aggressors such as UV, histamine and toxic chemicals. It is also believed to support the skin barrier functioning, reducing water-loss via the skin to improve hydration levels in the epidermis.