Vitamin C

About Vitamin C

Vitamin C, or ascorbic acid, is a water soluble vitamin required for collagen synthesis, where it acts as a cofactor for the enzymes that hydroxylate proline and lysine. It is also a major water soluble antioxidant, supports immune function and wound healing, and enhances absorption of non heme iron from plant foods eaten at the same meal. Unlike most mammals, humans cannot make vitamin C because of a mutation in the gene for L gulonolactone oxidase, so it must come from the diet, chiefly fruits and vegetables. Official recommended intakes vary by age, sex and life stage, and smokers are generally considered to have higher requirements. Deficiency causes scurvy, marked by bleeding gums, loose teeth, small skin hemorrhages, poor wound healing and fatigue, a disease that once devastated sailors on long voyages. In 1747 the naval surgeon James Lind ran one of the earliest controlled clinical trials, showing that citrus fruits cured scurvy. An upper intake level has been set because very large intakes can cause digestive upset and may raise kidney stone risk in susceptible people.