Vitamin C is a water-soluble vitamin, meaning that the body doesn’t store it and must acquire it from food, including citrus fruits, broccoli, and tomatoes. It is needed to make collagen, as well as healing wounds, repairing and maintaining bones and teeth. Vitamin C is an antioxidant, which blocks some of the damage caused by free radicals, substances that damage DNA. The build-up of free radicals over time may contribute to the aging process. It is used in cosmetics and skin care to reduce erythema from overexposure to the sun.