askorbiinihappoon

Askorbiinihappo, known in English as ascorbic acid and commonly referred to as vitamin C, is a water-soluble micronutrient essential for humans. It cannot be synthesized endogenously in humans and must be obtained through the diet or supplements. The compound has widespread roles in metabolism and tissue maintenance, and a deficiency causes scurvy.

Chemically, ascorbic acid has the formula C6H8O6. It exists in reduced and oxidized forms, with dehydroascorbic acid as the oxidized product. It acts as a potent antioxidant and reducing agent, and is sensitive to heat, light, and air, which can diminish its activity in foods and supplements.

In the body, ascorbic acid serves as a cofactor for several enzymes, notably prolyl and lysyl hydroxylases required for collagen synthesis. It also facilitates iron absorption by reducing ferric iron to the more soluble ferrous form and participates in neurotransmitter synthesis and immune function. Humans lack the enzyme to synthesize it, unlike many other animals.

Recommended intakes vary by guideline, but common values are about 90 mg per day for adult men and 75 mg per day for adult women; smokers may need more. Rich dietary sources include citrus fruits, berries, peppers, leafy greens, and fortified foods. Severe deficiency leads to scurvy, characterized by gum disease, skin manifestations, and impaired wound healing.

Uses of ascorbic acid include its role as a food additive and antioxidant to preserve color and flavor, as well as applications in cosmetics and medicine. It is generally safe at normal dietary intakes, but high-dose supplementation can cause gastrointestinal upset and diarrhea; typical upper intake limits are set around 2,000 mg per day for adults.