Corn: Evil Filler or Nutritious Additive?
Last week, Skeezix and I visited Iams/Eukanuba's facilities in Dayton, Ohio. This is one in a series of posts on what I learned.
Every discussion of corn in the cat's diet starts out something like this: "You have corn on the cob for dinner, and the next morning, if you care to peek, you'll note it has been expelled from your digestive tract wholly intact. Thus, it's only a cheap nutrition-free filler in pet food."
When it came to discussing the nutritional value and makeup of Iams and Eukanuba foods last week, the word on the tip of everyone's tongue was CORN, spoken with the same derision as one might say "cyanide" or "rat poison."
At the earliest opportunity, I asked Dr Maury Docton, DVM (right), the Technical Services Vet at Iams/Eukanuba, what role corn plays in the composition of their foods, and whether the new grain-free diets are a better bet for our pets.
We were in for an episode of Mythbusters.
There's been a lot of recent press about grain-free diets, with corn, wheat and rice portrayed in a negative light.
According to Dr Maury the most common myths include:
- Corn is not digestible
- Corn causes allergies
- Cats don't have the ability to digest grains
Dr Maury explained that corn is a nutritionally superior grain because it provides a highly available source of complex carbohydrates and substantial amounts of essential amino acids and fatty acids, providing more of the nutritional building blocks the pet needs for repair and maintenance of its body. And, corn minimizes blood glucose response to help maintain a healthy weight and blood sugar level.
To access the nutritional part of corn, you have to remove its outer hull and produce ground corn meal which is highly digestible. Although there are individual variations, once the hull is removed, ground corn is less than 2% fiber; therefore 98% digestible by your cat. Being 98% digestible means that more of the nutrition stays inside your cat, and less ends up in the litter box.
The only part of an ingredient that can trigger an allergy is the protein portion of that ingredient. Unless corn is used as a protein, in its gluten form, it is very unlikely to trigger an allergic reaction -- corn meal contains less than 8% protein. Beef, dairy and fish account for most reported food related allergies in cats. Of food ingredients reported in veterinary medical literature to cause adverse reactions in cats, corn was at the bottom of the list, just above egg*.
The trend to replace grains with fruit and vegetables for the same carbohydrate function is well-meaning, but as yet there is little research documentation to prove how they will affect the energy level and glycemic response of the cat. Although you won't see cats in the wild chowing down corn on the cob, they do consume a diet of up to 10% carbohydrates, which they get from the stomach contents of their prey.
Bottom line: When processed correctly, corn is an excellent source of complex carbohydrates, as proven by data that Iams has collected during 50 years of research. Although cats are obligate carnivores, most do need a small percentage of complex carbohydrates in their diets for energy, and they will get that from a correctly balanced diet.
In rare cases, corn may cause an allergic response, but if your cat eats a food that contains corn and develops an allergic reaction, it's far more likely due to beef, dairy or fish.
Like humans, some cats may need to be on low-carb diets, in which case your vet can recommend the best food for your cat's needs.
In the interest of full disclosure, this trip was fully paid for by Iams/Eukanuba. I've fed my cats Eukanuba for nearly 20 years, and the only cat of mine with digestive issues is the one who won't eat the Eukanuba, but sticks to an all-meat Catkins diet.
* source: Advances in Small Animal Medicine and Surgery, Vol 5, Issue 9, 2002.