Retinoic acid is a naturally occurring form of Vitamin A, which was the first vitamin to be scientifically recognized and catalogued. A fat-soluble alcohol, vitamin A can be found in meats, dairy products, and cod liver oil, while a variety of fruits and vegetables contain carotene, the precursor of the vitamin.

An essential part of the human diet, retinoic acid is involved in a variety of bodily functions. The substance, for instance, plays a part in the embryonic development of the hindbrain and faciocranial nerves, as well as the differentiation of neurons. Maintenance of healthy skin, hair, mucous membranes, bones, and teeth, are also facilitated by retinoic acid. In fact, the biochemical, which is believed to increase the rate of cell division and turnover, is often used topically in skin-improvement treatments, such as Renova and Retin-A.

Although the body needs sufficient amounts of retinoic acid to sustain good health, excessive amounts of the vitamin can be toxic. Known as hypervitaminosis A, the condition may cause edema, lesioning of the skin, and liver damage. Overconsumption of vitamin A is perhaps most pronounced among natives of Alaska, who may suffer acute symptoms of painful headaches and extreme drowsiness from eating polar bear liver. Those that chronically intake too much vitamin A may also experience irritability, generalized pain, and loss of appetite.