Ascorbic acid

Ascorbic acid, commonly called vitamin C, is a water-soluble nutrient and reducing agent. Humans must obtain it from food because they cannot synthesize it.

Redox reaction: A chemical reaction in which electrons move between substances, changing their oxidation states. Ascorbic acid acts as an electron donor in reactions that maintain cellular redox balance.
Scurvy: A disease caused by prolonged vitamin C deficiency, marked by impaired connective-tissue maintenance. It is the characteristic disease prevented by adequate ascorbic acid intake.
James Lind: A Scottish naval surgeon whose 1747 trial compared treatments for scurvy among sailors. His controlled comparison showed that citrus fruit rapidly improved scurvy symptoms.
Vitamin E: A group of fat-soluble compounds that protect cell membranes from oxidative damage. Unlike water-soluble ascorbic acid, vitamin E acts mainly in lipid environments.
Collagen: A structural protein that forms a major component of connective tissues in animals. Ascorbic acid enables enzymes to modify collagen residues, supporting stable collagen structure.
Dietary Reference Intake: A set of nutrient intake standards used to assess and plan diets. Its vitamin C recommendations translate nutritional evidence into daily intake targets.
Albert Szent-Györgyi: A Hungarian biochemist who isolated and studied compounds including hexuronic acid, later identified as vitamin C. His research helped establish the identity of ascorbic acid.
Glutathione: A small sulfur-containing molecule that serves as a major cellular antioxidant and redox buffer. It is an intracellular antioxidant system distinct from dietary ascorbic acid.
Prolyl hydroxylase: An enzyme that hydroxylates proline residues in proteins, including collagen. Ascorbic acid helps keep its iron cofactor in the active state during collagen modification.
Food preservation: Methods that slow food spoilage and maintain food quality during storage. Ascorbic acid limits oxidation and is used to protect color and flavor in foods.

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