Vitamin A: Essential for

healthy eyes and vision

growth, repair and cell differentiation

health of epithelial cells (Epithelial cells form the barrier between an organism and its external environment. These cells either may be involved in the secretion or uptake of liquids or nutrients, or may perform a simple barrier function.)

protection against infection

a healthy reproduction system
Absorption and metabolism
Fat is necessary for vitamin A absorption.
Deficiency
Symptoms include night blindness, xerophthalmia, dry skin, retarded growth, increased susceptibility to infection and cancer.
Sources
Good sources of pre-formed vitamin A include liver, butter, whole milk and egg yolks.