Which chemical compound is commonly called vitamin C?

Ascorbic acid is the chemical compound commonly called vitamin C.

Vitamin C is a water-soluble vitamin and antioxidant found in foods such as citrus fruits, peppers, broccoli, and blackcurrants. Humans cannot synthesize it because they lack the enzyme needed for the final step of its production, so it must come from the diet.

Ascorbic acid is required for collagen formation, which supports connective tissue, skin, blood vessels, cartilage, and bone. It also helps maintain normal immune function and improves absorption of non-heme iron from plant foods.

Severe deficiency causes scurvy, historically a major problem among sailors on long voyages. Vitamin C is not the same as citric acid, the sour acid abundant in citrus fruits. Both can occur in oranges, but they perform different chemical and biological roles.