Natural Factors Quercetin Complex - With antioxidant bioflavonoids. Flavonoids, such as quercetin, grape seed extract, coenzyme Q10, and other antioxidant nutrients are found in high amounts in vegetables and fruits. Increased intake of these powerful nutrients can be helpful in the prevention and management of many conditions, including inflammation, cardiovascular disease, and diabetes. They can also help to maintain optimal health and prevent accelerated aging. Natural Factors Quercetin Complex is an exceptional antioxidant formula specially developed to maintain optimal health, combat disease, and prevent accelerated aging.