Vitamin A was the first vitamin to be discovered and named, back in 1913. Scientists noticed that animals whose diets lacked certain foods got inflamed eyes. In the 1930's, scientists discovered that a substance in plants called beta carotene (BAY-tuh CARE-uh-teen) could be converted to Vitamin A in the body. Vitamin A is a family of compounds that includes retinol (RET-uh-nahl) and carotenoids (kuh-RAH-tuh-noids), which help regulate and maintain several essential bodily functions. It combines with a special protein in the retina of the eye that's necessary for night vision. It's important for smooth skin, sharp vision, maintaining moisture in tissues, and even bolstering the immune system to lower the risk of developing certain types of cancer. Some evidence indicates that Vitamin A helps prevent oxidation of L-D-L cholesterol, thus helping prevent heart disease. Beta carotene and other substances found in dark green, orange, and dark yellow vegetables and fruits may protect skin from cancer and other damage caused by exposure to the sun and protect the body from environmental pollutants. Good sources of Vitamin A include sweet potatoes, carrots, spinach, cantaloupe, broccoli, watermelon, and squash. A deficiency of Vitamin A causes changes in the skin, eyes and eyesight, and teeth. Lack of the vitamin can also cause retarded growth, deformed bones and teeth, and blindness.