Ascorbic acid: Vitamin C, an essential nutrient found mainly in fruits and vegetables. The body requires ascorbic acid in order to form and maintain bones, blood vessels, and skin. Ascorbic acid also promotes the healing of cuts, abrasions and wounds; helps fight infections; inhibits conversion of irritants in smog, tobacco smoke, and certain foods into cancer-causing substances; appears to lessen the risk of developing high blood pressure and heart disease; helps regulate cholesterol levels; prevents the development of scurvy; appears to lower the risk of developing cataracts; and aids in iron absorption. Ascorbic acid can cause adverse reactions when taken with some drugs.