Mega cbr is a complex of Vitamin C ascorbic acid , citrus bioflavonoids, and rutin, a non citrus bioflavonoid. Vitamin C and bioflavonoids occur naturally together in plants, where they provide a synergistic antioxidant effect. Vitamin C, also referred to as ascorbic acid, is the single most commonly used vitamin supplement. It plays a major role in the formation of collagen a structural protein in connective tissue , amino acid metabolism and hormone synthesis, and the utilization of many nutrients, such as folic acid and iron. It is also a key factor in the body's natural defenses.