Vitamin C

Vitamin C, or ascorbic acid, is a water-soluble vitamin humans must obtain from food. It supports collagen formation, antioxidant activity, and several enzyme reactions.

Collagen: A family of structural proteins that gives connective tissues tensile strength. Vitamin C enables enzymes to stabilize collagen’s characteristic triple-helical structure.
Scurvy: A disease caused by prolonged vitamin C deficiency, marked by impaired connective tissue maintenance. Its bleeding gums, bruising, and poor wound healing follow defective collagen formation.
Dietary Reference Intake: A set of nutrient-intake reference values used to plan and assess diets. Its recommended allowances specify daily vitamin C intake by age, sex, and life stage.
James Lind: A Scottish naval surgeon whose 1747 trial compared treatments for scurvy among sailors. His citrus treatment comparison provided early evidence that fruit could prevent scurvy.
Vitamin C synthesis in animals: The production of ascorbate from glucose through a metabolic pathway in many animals. Humans lack a functional enzyme in the final step and therefore depend on dietary vitamin C.
Prolyl hydroxylase: An enzyme that hydroxylates proline residues in collagen and other proteins. It requires vitamin C to maintain the iron needed for collagen hydroxylation.
Wound healing: The coordinated biological process that repairs damaged tissue. Adequate vitamin C supports collagen deposition during tissue repair.
Citrus fruit: Fruits of the genus Citrus, including oranges, lemons, and grapefruit. Citrus is a familiar dietary source, though many other fruits and vegetables contain vitamin C.
Scurvy in the Age of Sail: A widespread deficiency disease among sailors on long voyages before reliable fresh-food supplies. The disease created the practical problem that led to citrus rations and nutrient research.
L-gulonolactone oxidase: An enzyme that catalyzes the final step of ascorbate synthesis in many animals. Humans cannot make vitamin C because the gene encoding this enzyme is nonfunctional.

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