Vitamin A. Molecular model of vitamin A, also called retinol (formula: C20H30O). The atoms are spherical and colour-coded: carbon (blue), oxygen (red) and hydrogen (white). Vitamin A is essential for normal growth, for bone and teeth formation, night vision and for protecting against infection. It is found in animal foods such as liver, fish- liver oil, eggs and dairy products. Carotene, from sources such as green vegetables and fruits, is converted into vitamin A in the liver. Deficiency leads to night-blindness, dry skin and eyes, and reduced resistance to infection. Prolonged excess intake can cause hypervitaminosis A, leading to nausea, hair loss and liver damage.