Vitamin A (beta carotene). A capsule of beta carotene, a precursor of vitamin A. In nature this is a yellow pigment found in a variety of fruits and vegetables, including carrots. In the human liver, beta carotene is converted to the primary alcohol vitamin A. This vitamin is essential for normal growth, formation of bones and teeth, cell structure, protection against digestive and urinary tract infections, and for night vision. Deficiency of vitamin A can result in weight loss, stunted growth in children, and night blindness.