Vitamin C or -ascorbate is an essential nutrient for higher primates, and a small number of other species. The presence of ascorbate is required for a range of essential metabolic reactions in all animals and plants. It is made internally by almost all organisms, humans being one notable exception. It is widely known as the vitamin whose deficiency causes scurvy in humans. It is also widely used as a food additive.The pharmacophore of vitamin C is the ascorbate ion. In living organisms, ascorbate is an antioxidant, as it protects the body against oxidative stress, and is a cofactor in several vital enzymatic reactions.The uses and the daily requirement of vitamin C are matters of on-going debate.