The most commonly discussed vitamin, ascorbic acid (vitamin C), is a strong reducing compound that has to be acquired via dietary ingestion. Major dietary sources include fruits (especially citrus) and vegetables (e.g., tomatoes, green peppers, cabbage, leafy greens, and potatoes).
Ascorbic acid is important in formation and stabilization of collagen by hydroxylation of proline and lysine for cross-linking and conversion of tyrosine to catecholamines (by dopamine-hydrolase). Ascorbic acid is essential for the enzymatic amidation of neuropeptides, production of adrenal cortical steroid hormones, and metabolism of tyrosine and folate. It also plays a role in lipid and vitamin metabolism and is a powerful reducing agent or antioxidant. Specific actions include activation of detoxifying enzymes in the liver, antioxidation, interception and destruction of free radicals, preservation and restoration of the antioxidant potential of vitamin E, and blockage of the formation of carcinogenic nitrosamines. Vitamin C promotes collagen synthesis, maintains capillary strength, facilitates release of iron from ferritin to form hemoglobin, and functions in the stress response. In addition, vitamin C appears to function in a variety of other metabolic processes in which its role has not been well characterized.
The deficiency state, known as scurvy, is characterized by hemorrhagic disorders, including swollen, bleeding gums and impaired wound healing and anemia.
Decreased In