The Kernel of Truth About Corn

Somewhere along the line, grains – and in particular, corn – have gotten a bad rap where pet food is concerned. And as a result, increasingly, clients are telling us they’re choosing (or looking for a recommendation from us for) grain-free diets for their pets. But here’s the thing: Grains aren’t the bad guys that Dr. Google, a dog breeder, a clerk in a pet store, an ad on TV, marketing on product packaging, or a well-meaning fellow dog-enthusiast at the dog park are making them out to be.

Let’s take a look at the three most common misconceptions driving people’s concerns about corn in particular.


If you’re thinking that the ancestors of cats and dogs didn’t have grains on their menu and so their modern-day counterparts aren’t capable of digesting them – or if you think the issue is that cats and dogs lack the necessary enzyme in their saliva to digest starch – you’re only partly right.

The fact is: Grains were introduced to the diets of cats and dogs when we started domesticating them thousands of years ago. During that time, cats and dogs have become quite good at digesting grains. Evolution will do that. If you compare, for example, the genes of dogs and their wolf ancestors (a Swedish geneticist did exactly that), you’ll find that domesticated dogs express genes responsible for digesting starch at levels at least 7 times higher than wolves. So dogs have the tools (i.e., the genes) to do it, but do they use them? In fact, they do. And so do cats. Digestibility studies have shown that when cats and dogs are fed a diet containing 50% corn, they’re able to digest more than 95% of it.

As for that digestive enzyme (amylase) that cats & dogs lack in their saliva? Not an issue. Why? Because it’s secreted in their intestines where it does the work of digesting starch.

Meanwhile, keep in mind that it’s the cellulose in plant materials that make them harder to digest than other ingredients. That’s why you’ll see undigested whole kernels of corn in your pet’s poop if you feed him/her whole kernels of the stuff. But the corn in pet food is different. Properly processed pet foods contain corn that’s been ground and cooked (thereby breaking down that cellulose), making corn almost 100% digestible.

Nutritional Value

If you think corn is just a pet food filler (essentially empty calories that have no nutritional value), you’re right about fillers serving no nutritional purpose. But corn is no filler.

The fact is: Corn packs a nutritious punch and is one of the most nutritionally superior grains used in pet food. What it brings to the table (or rather, the food bowl) is a variety of valuable (& in some cases, essential) nutrients:


Amino acids are the building blocks of protein. “Essential” amino acids are ones the body needs but can’t make so have to come from food. Different ingredients contain different amounts of those amino acids and are assigned a “biological value” (BV) accordingly. Corn and meats such as beef and chicken have almost identical BVs. In other words, corn is almost as good a source of protein as certain meats. And when you combine corn with other plants, it’s BV is even better. Who knew?? (Probably not your average Joe or Josephine who dishes out nutrition advice without the training or science to back it up.)

So, some corn is included in pet food along with meat in part because corn provides a less expensive protein source than meat and is more resistant to spoilage.

Complex carbohydrates

Carbs break down into simple sugars that supply the energy cells need to function. Carbs are a “must have.” Animals with high energy demands (athletes and pregnant or lactating individuals, for example) need higher levels of carbs while sedentary animals (the proverbial couch potatoes) need less. But all cats and dogs need some level of carbs to provide their bodies with energy. Corn is one such source. And it’s a complex carb that breaks down more slowly than a simple carb, so as carbs go, it’s better at managing blood sugar levels.

Essential fatty acids

Corn has lots of linoleic acid in it – an omega-6 fatty acid that contributes to healthy skin and a shiny coat. “Essential” means the same thing here: need it, can’t make it, gotta get it from food.

Vitamins & minerals

Corn contains B vitamins, vitamin E, magnesium, and phosphorous to name just a few.


Corn is a win-win for digestive health because it adds fibre to a pet’s diet. Fibre helps with gut motility (moving things along) and improves the quality of your pet’s poop. And who doesn’t want quality poop? What’s more, while corn is no fill-er, the fibre it provides tends to be fill-ing and can help a pet feel more satisfied after a meal.


If you think you need to avoid corn in your pet’s food because you’re afraid it’ll cause allergies, you’d be right to avoid it if your pet actually is allergic to corn. But allergies to corn are RARE in cats and dogs.

The fact is: True food allergies that cause either gastrointestinal or skin issues are uncommon in cats and dogs. Only about 10 to 20% of allergies are caused by food. Most allergic skin reactions are caused by flea bites or environmental allergens (pollen, dust mites, and so on). And most GI sensitivities to food aren’t due to allergic reactions per se but rather something in the makeup of a diet (how much fat and fiber it contains, how digestible it is, and so on). When cats and dogs DO have bona fide food allergies, it’s usually to an animal protein (beef, chicken, or lamb, for example). Other culprits include fish, dairy, egg, soy, and wheat. But RARELY corn.

A Final Note

None of this is to say that you shouldn’t feed your pet a grain-free diet. Just don’t avoid diets containing grains for the wrong reasons. And if you’re going to go grain free, be sure you know what you’re getting: not all grain-free diets are free of starch (it’s just supplied in a different form, like potato, for example) nor are they all balanced to provide optimal nutrition.

Dr. Iz Jakubowski