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Summary of Corn in Pet Foods Article

This is a summary of Dr. Marie's article about corn in pet foods. You can find the original, full length article here: Corn in pet foods.

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Everything you need to know about corn in pet foods.

(The following is a summary of an in depth article written by Dr. Marie Haynes of Ask A Vet Question. You can read the full article here: Corn in pet foods.)

Is corn in pet food a bad thing?

The benefits of corn

Corn has a lot of really nutritious qualities including high digestibility, and great nutrients such as essential fatty acids, carotene and vitamin E. It is also a good source of protein.

The makeup of corn:

Corn is made up of corn bran (which is the outer portion containing fiber), corn grits, and corn gluten (which when ground into meal is a very concentrated source of protein.)

"Corn gluten meal" doesn't sound very appetizing, but actually is a very good source of protein and nutrients. Corn gluten meal on its own is not a complete source of nutrition as it is lacking the amino acids lysine and tryptophan. Therefore, when corn is present in a diet, we do need another protein source (usually meat) to complete the nutrient profile.

Corn and Allergies

You will read on the internet that many allergies in pets are caused by corn, but the truth is that corn is actually less likely to cause allergies than many other ingredients. One study showed that corn was responsible for only 3% of allergies in dogs. Another study showed that corn and rice were very similar in the fact that neither of them were highly allergenic.

Does corn contribute to behavior problems?

Some people have claimed that a diet containing corn will contribute to behavior problems. This is because corn does not contain tryptophan. If an animal is low in tryptophan, it can affect the serotonin levels in the brain. However, a thorough review of the literature shows that as soon as you add another protein source to the diet, there will be sufficient tryptophan. There are no studies that show that corn as an ingredient in pet food contributes to behavior issues.

What if corn is the first ingredient?

It is really hard to read a food label and determine whether or not it is good quality. Some foods may look superior if they have, for example, chicken as the first ingredient (i.e. before any corn or corn gluten is mentioned). However, once the water is removed from the chicken and it is broken down into meal (in order to be made into kibble), then it actually is likely to weigh less than the corn portion listed on the ingredient list. Some food companies will purposely purchase their chicken as meat rather than chicken meal simply so that they can list it on the ingredient list as the first ingredient.

Another thing to consider is that there are different qualities of corn and meat. Just because meat is listed first doesn't mean it is high quality meat. As a veterinarian, I can't read the ingredients on a food label and tell you if it is a good food.

Corn Quality

In the United States there are 5 different grades of corn. Lower grades of corn will be more susceptible to aflatoxin contamination and grain mites (which contribute to allergies.) A reputable food company will use human grade (i.e. Grade 1 or 2) corn in their products.


There are a lot of good things that can be said about corn. It is not by any means perfect. But, we should not be too quick to judge a pet food simply because there is corn on the label.

For references, read the original, full length article, here.

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Dr. MarieDr. Marie is a veterinarian who practices in a busy animal hospital in Ottawa, Ontario. She created Ask A Vet Question as a resource for good, accurate veterinary advice online. Dr. Marie treats dogs, cats, hamsters, guinea pigs, and rats. She has been a vet since 1999.

Is an online vet visit just as good as a trip to your veterinarian? No! But, many times, asking an online veterinarian a question can help save you money. While Dr. Marie can't officially diagnose your pet or prescribe medications, she can often advise you on whether a vet visit is necessary. You can also ask Dr. Marie for a second opinion on your pet's condition.