Vitamin C, or ascorbic acid, is a water-soluble vitamin, which means it is not stored in the body and must be replenished daily. It is responsible for the growth and repair of tissue in all parts of your body. Vitamin C is necessary to form collagen, a protein used to make skin, scar tissue and blood vessels. A natural antioxidant, Vitamin C also blocks damage caused by free radicals, which are by-products of the digestive process and can also be found as toxins in the air.