Corn has been a controversial ingredient in cat food for as long as I can remember. Do cats need corn? Why is corn a common ingredient used by so many pet food companies?
Before we start let's look at cats' digestive system. Cats have a much shorter digestive tract than humans, dogs and many other mammals. Food only stays in their system for a few hours compared to 24 hours for humans. Their digestive system is designed to consume a smaller amount of food that is highly dense and packed with energy, vitamins, minerals and so forth.
Cats' liver is constantly working at a high enzyme activity which is perfect for a high protein diet. We are able to lower our liver enzyme activity when we consume low protein foods. However, cats cannot decrease activity of enzymes when fed low-protein foods. Also, cats are not equipped with the ability to break down the cell walls of vegetables and extract the nutrients from a plant. They require high grade protein to sustain their daily needs. This makes cats obligate carnivores and should only be fed on meat based foods.
Many companies use corn because it contains low grade protein which is much cheaper than muscle meat. Though many companies have figured out the technology to process corn so that cats can digest it or will not develop allergy, the protein is far from ideal. Since corn does not provide many important vitamins and nutrients such as taurine (found primarily in muscle meat), many companies fortify their products with artificial nutrients.
Some companies claim that corn provides amino acids or fatty acids for cat food. But quite the contrary, corn lacks those important nutrients that our cats need. The rule of thumb is that if your cat food has corn (corn bran, corn germ meal, ground corn, corn gluten, corn gluten meal, etc) as one of the top ingredients, you should definitely avoid it.