Vitamin C (ascorbic acid) is potent antioxidant and an essential nutrient necessary in small quantities to maintain a variety of metabolic functions in animals and plants. Vitamin C primarily exists in its reduced form, ascorbic acid. In humans, it can be obtained mostly from foods. Sources of vitamin C include fresh fruits (especially citrus) and vegetables, as well as oral supplements. Sunlight and environmental pollution can deplete vitamin C in the skin. Vitamin C supplementation is often used for preventing and lessening the severity of the common cold. Although unproven, vitamin C has been reported to improve arthritis, gum disease, osteoporosis, gum disease, asthma, bronchitis, depression, infertility, immune function, hay fever, difficulty thinking, dementia, Alzheimer’s disease, physical and mental stress, fatigue, autism, and attention deficit-hyperactivity disorder (ADHD), eye disorders, heart disorders (including preventing clots in veins and arteries, heart attack, stroke, and controlling high blood pressure and elevated cholesterol), bronchitis, human immunodeficiency virus (HIV) disease, stomach ulcers caused, tuberculosis, dysentery, bladder and prostate infections, enhancing physical endurance, and slowing aging, Vitamin C can be applied to the skin for protection from damage caused by ultraviolet (UV) light (sun exposure), pollutants, and other harmful environmental factors. Many skin care products contain vitamin C to improve fine lines and reduce both discoloration and inflammation. However, these products may not be effective on the skin because the concentration of ascorbic acid is too low, it cannot be easily absorbed by the skin, or air and light exposure de-stabilizes the product. At high enough concentration (at least 10%), and properly formulated, this antioxidant can protect against UV damage.