Grain-free cat food is a type of cat food that does not contain grains and is usually composed of natural ingredients such as animal protein, meat, fish, poultry, vegetables and fruits. Grain Free: Traditional cat food often contains grains, such as corn, wheat, and rice, but these grains may cause cat allergies or indigestion. Grain-free cat food does not contain grains, so it can reduce the risk of cat allergies or indigestion