The diet of each type of animal must include a specific group of essential nutrients essential amino acids ,essential fatty acids , vitamins and minerals to provide the raw materials needed to synthesize the different kinds of organic molecules the animal must have to sustain life. The essential nutrients are materials the animal because the ability to synthesize particular molecules in a genetic trait acquired through natural selection and because each type old animal has a unique evolutionary history.

In general the more simple and primitive animals are able to synthesize more or the material they require than can the more complex and advances animal. the ability to construct many material was lost during the enzymes required to synthesize them were no longer necessary and were lost from the genetic repertoire

All animals require vitamin c for it is essential in the construction and maintenance of substance that bind cells together specially in skin , bone and muscle. The only animal that require vitamin c in there diet how ever are those with a ancestors that regularly consumed and adequate supply of vitamin c and gradually lost the enzymes necessary for its synthesis.