The oldest known nutrient-deficiency disease, called scurvy (SKUR-vee), was commonly diagnosed in sailors and was easily cured by eating citrus fruit. In fact, the nickname for British sailors became 'limeys.' It wasn't until 1932, however, that researchers isolated Vitamin C and named it 'ascorbic (uh-SCORE-bick) acid.' Vitamin C helps form and maintain collagen (CAH-luh-jun), a protein that forms the basis for connective tissue, the most abundant tissue in the body. A deficiency of the vitamin causes bleeding gums, dry skin, damage to blood vessels, loose teeth, gangrene, depression, and stomach disorders, among other problems. It's also good for iron deficiencies, because it helps the body absorb iron. Research has shown that regular consumption of C may help eliminate the effects of oxidation in the body, which may reduce the risk of certain diseases, including heart disease and cancer. However, taking it won't prevent these diseases alone, unless it's combined with a low-fat balanced diet, regular exercise, and avoidance of unhealthful lifestyle practices, such as smoking and excess drinking. Eating plenty of fresh vegetables and fruits, especially citrus, can satisfy your basic requirement for this important vitamin.