Vitamin A is used by the body for normal growth, and for the production and maintenance of skin, teeth and bone. The form of vitamin A found in mammals is called retinol. The body makes vitamin A from carotene, which is found in the yellow pigment of some plants. Good sources of vitamin A are thus yellow and yellow-orange fruits and vegetables (squash, oranges, cantaloupes, etc.), as well as butter, egg yolks, and cod liver oil.

A deficiency in vitamin A causes interference with growth, reduced resistance to infections, night blindness and impaired visual acuity. Vitamin A is also an anti-oxidant, and so it is thought to be helpful in preventing cancer. Excessive intake of vitamin A can be toxic, so megadoses are not recommended.