Vitamin C (ascorbic acid) is one of the most important antioxidants. Blood levels of vitamin C are used to measure nutritional, immune, and cardiovascular status. It's needed for growth, development and repair of all body tissues. Vitamin C deficiency may be caused by malnutrition (scurvy), malabsorption, inflammatory bowel disease, alcoholism, pregnancy, hyperthyroidism, and kidney failure. Smokers have also been shown to have lower levels than non-smokers. Alternative Name(s): Ascorbic Acid