Cats need lots of protein and the right amino acids in their diet, and too low levels can be dangerous. Even a single meal without the amino acid arginine can be fatal, and a lack of taurine can lead to serious complications such as heart disease and blindness. Because animal products contain large quantities of both arginine and taurine, cat food must contain animal protein. A completely vegetarian diet is not suitable for cats.
Cats also need fat in their diet, partly for energy but also for the three essential fatty acids. One of these, arachidonic acid, is always included in cat food. Omega-3 fatty acids EPA and DHA are not considered essential for cats but have health-promoting properties which can benefit the development of the brain. EPA and DHA should therefore always be present in kitten food.