Vitamin C, or ascorbic acid, is a white, crystalline, water-soluble substance found in citrus fruits and green vegetables. As an antioxidant, vitamin C scavenges free radicals in the body and protects tissues from oxidative stress. Vitamin C also promotes the absorption of iron, while preventing its oxidation. Vitamin C is a vital co-factor to the formation of collagen, the connective tissue that supports arterial walls, skin, bones, and teeth. It also assists in the production of thyroxin, the thyroid hormone that regulates metabolic rate. More vitamin C is contained in the adrenal glands than any other organ in the body and is required at higher levels during times of stress. Physical stresses on the body such as infections, cigarette smoking, extreme temperatures, ingestion of heavy metals, and chronic use of certain medications also signal the need for increased intake of vitamin C. Along with ascorbic acid, vitamin C also comes in at least two other forms: chemically bonded to minerals as ascorbates, and as the fat-soluble ascorbyl palmitate. Both of these forms are nonacidic. This TwinLab product contains a unique calcium-bound ascorbate complex. This is a nonacidic form of vitamin C that may have a longer serum half-life than regular ascorbic acid. The product also contains a citrus bioflavonoid complex.