The first vitamin ever discovered, vitamin A is one of four fat soluble vitamins. This vitamin, along with the other fat soluble vitamins D, E and K, dissolves more easily in oil than in water.
Retinol is another term for vitamin A and indicates that it is involved in the retina of the eye.
Other names for vitamin A are retinene, retinoic acid and retinyl palminate. There are four types of vitamin A that are contained in the retina and each of these types contain photopigments that adapt to changes in light. A intake decreases the retina's ability to respond to these changes. Vitamin A is essential for maintaining healthy hair, skin, and mucous membranes throughout the body. Vitamin A is also necessary for strong teeth.