Most dry cat food contains some form of corn. In recent years, a number of advocates expressed concern about the harmful effects of corn on cat health, including food allergies, diabetes, and obesity. Cat food companies are accused of using corn only because it is inexpensive, not because of the nutritional value it provides. Cat food companies defend their use of corn as providing unique benefits.
My awareness of corn in cat food began when my new kitten, Buddy, began having chronic diarrhea with a corn meal yellow color. Buddy’s veterinarian suggested some expensive tests, but with the yellow color as a clue, I suggested we try a change in diet first. Reading labels, I discovered different cat food brands contained various forms of corn, such as whole corn, corn meal, corn gluten, and corn gluten meal. Buddy’s food contained corn meal. Would food containing gluten rather than corn meal alleviate the diarrhea? Yes! Buddy’s diarrhea problem disappeared with the switch to food with corn gluten meal. Though not a scientifically proven conclusion, Buddy’s cure does suggest that he had a food intolerance to corn meal.
Corn is believed to cause food allergies or food intolerances in cats. Doctors Foster and Smith of the Pet Education website define a food allergy as causing itchiness and skin problems, whereas a food intolerance causes a gastrointestinal reaction such as diarrhea or vomiting. They cite studies which indicate that corn is among the most common food offenders, along with other common ingredients, including beef, lamb, and seafood. Similarly, Hills Pet Nutrition, Inc. maintains that corn resulted in fewer allergy cases than meat based protein sources such as beef and chicken.
So, what is the difference between various corn entities found on ingredient labels? Whole corn contains about 80% carbohydrates (primarily starch) and about 8% protein (Royal Canin USA, Inc, Purdue University, and Bunge Limited). Finely ground whole corn is called corn meal flour. The protein portion of corn is called corn gluten. The dried form of corn gluten is called corn gluten meal.
Veterinarian Lisa A. Pierson states that cats are obligate carnivores – they eat primarily animal based proteins in the wild. Animal based proteins contain all of the amino acids required by a cat’s digestive system. Plant based proteins do not. Pet food companies add in the missing components separately, as exemplified by the addition of the meat based amino acid taurine. Royal Canin USA, Inc. claims that no single source of protein is ideal, and that corn gluten provides a source of protein which augments meat protein. Each has its advantages, and combining different protein sources in a food formulation allows foods to be developed with specific features, such as for weight loss.
According to Dr. Pierson, dry cat food often contains high levels of carbohydrates, 35 -50%. Cats have no dietary need for carbohydrates and in the wild they consume only 3-5% carbohydrates. She believes that too many carbohydrates can cause serious diseases in cats including diabetes, obesity, pancreatitis, and liver disease. Both Royal Canin USA, Inc. and Hill’s Pet Nutrition state that carbohydrates provide a good source of energy for cats.
The jury is still out on the effects of corn in cats’ diets, and I encourage you to read further on the subject in order to make the right decision regarding what to feed your cat.
References
Doctors Foster and Smith, “Food Allergies and Intolerance in Cats”, Pet Education
Hill’s Pet Nutrition, Inc., “Corn ‘” An Amazing Grain”, Hills Pet
Brent Mayabb, DVM, “Corn in Pet Food”, Royal Canin
D. E. Maier, “1995 Indiana Corn Quality Survey ‘” Composition Data”, ANSC.Purdue
Bunge Limited, “Typical Composition of Yellow Dent Corn”, Bunge North America
Lisa A. Pierson, DVM, “Feeding Your Cat: Know the Basics of Feline Nutrition”, Catinfo
