Solgar Vitamin A has many different functions. First it is related to the main-tenance of normal vision in dim light or the prevention of night blindness. It also aids in the growth and formation of body cells, making it essential for body growth. It is especially needed for bone growth. If the intake is not sufficient, bones will stop growing before the soft tissues are fully mature. Vitamin A is also needed for normal tooth development because the enamelforming cells are affected by lack of vitamin A. It is also important in the maintenance of healthy epithelial tissues. There are two kinds of epithelial tissues: (1) those that cover the outer surface of the body -- the resistant, protective skin (epidermis), and (2) those that line all the mucous membranes. Without vitamin A, the epithelial cells become dry and flat and gradually harden to form scales that shed. Vitamin A is also necessary for the health of the membranes lining the stomach, intestinal wall, bladder and urinary passages and for the health of the sex glands and uterus. Lastly, solgar vitamin A works better when there are sufficient body levels of zinc and an adequate intake of protein.