Vitamin A was the first vitamin to be discovered. It has been shown to be essential in maintaining good vision and promoting normal growth. It occurs in animal tissues as retinol but in plants as carotene-a precursor of vitamin A. It is necessary for the health of epithelial cells and the immune system. It's also required for the digestion of protein. Extra amounts are stored in the liver, but megadoses over time can be toxic.� Vitamin D works synergistically with vitamin A. It plays a role in absorbing and regulating calcium and phosphorus. It also helps build strong bones, teeth and skin. It is vital to the health of the nervous system and kidneys. Vitamin D works synergistically with vitamin A. It plays a role in absorbing and regulating calcium and phosphorus. It also helps build strong bones, teeth and skin. It is vital to the health of the nervous system and kidneys.
