Some have suggested adding carnatine, vitamin E and other nutrients, however, most cat foods contain these nutrients and it is still unclear if increased amounts provide any therapeutic benefit or what dose is necessary. This is a dangerous misrepresentation of the truth. The safest way to feed a cat is to use a commercial cat food made by a national name-brand cat food manufacturer. There is a lot of science behind pet food manufacture. Pet food manufacturers try to avoid problems but there is still much to know.
Manufacturers keep abreast of the latest information and change their diets to prevent deficiencies.
It is not in the interest of these manufacturers to make cats sick. Cat foods made by US manufacturers are mostly made from good quality ingredients. It is recognized that pet food ingredients are slightly less digestible than human foods but the difference is small. For example, the amount of energy derived from pet food ingredients is generally accepted as being slightly less than that from human food. Pet food contains extra ingredients to make up for this difference.