are potatoes good for dogs

Are potatoes good for dogs? Can my dog eat peas? Is a dog food OK as long as it doesn’t have corn, soy or wheat?

These are really common questions here at DNM and they’re valid ones. You want to avoid feeding harmful ingredients to your dog and that’s a good thing. But there’s a lot of marketing out there telling you some carbohydrates (like potatoes and peas) are a healthy addition to your dog’s diet.

But here’s the problem … that marketing is from people who want to sell you their food.

The truth is, there are some pretty compelling reasons not to feed any type of starchy carbohydrate to dogs. Let’s look at the top reasons to avoid starch …

#1 Mycotoxins

Mycotoxins are toxic byproducts of mold or fungus. Mycotoxins contaminate crops before they’re harvested or after they’re stored. They’re most commonly found in corn, barley, wheat, beets, peanuts and cottonseed, but other frequently affected foods include; sorghum, pearl millet, rice, wheat, soybean and sunflower seeds.

One of the most well-known mycotoxins is aflatoxin … and it’s the most carcinogenic (cancer-causing) naturally occurring substance known to man. A global survey conducted between 2004 and 2013 found mycotoxin contamination in over 76% of the samples of grains and byproducts destined for animal foods.

Aflatoxins target many of the organs in dogs but especially the liver, where they can cause toxicity, immunosuppression and cancer.

In the US, both human and pet foods are limited to 20ug of mycotoxin per kg. But grains usually contain several different types of mycotoxins and they can interact with one another to increase their toxicity. And the effects of mycotoxin exposure are cumulative and build up in your pet over time.

A 2015 study published in Animal Feed Science & Technology analyzed 48 commercial dry dog foods for the presence of five different mycotoxins. Half of the foods tested were low price and the other half were premium or super-premium foods.

bad foods for dogs

The study found that all of the lower priced foods and all but one of the premium foods were contaminated with at least two types of mycotoxin. Additionally, 52% of the samples were contaminated with three different mycotoxins while 25% were contaminated with four different types of mycotoxin. One premium brand was contaminated with all five mycotoxins that were tested for.

Many pet food companies test their ingredients for mycotoxin contamination and ask their suppliers for a certificate of analysis showing mycotoxins have been checked. But even if the food is under the allowable FDA limit, it doesn’t account for the dangers of combining mycotoxins. When more than one type of mycotoxin is present, they can interact and become more toxic – so the safe limit is likely only safe if there’s one type of mycotoxin present.

Dr Trevor Smith, an animal and poultry science researcher at the University of Guelph, claims that mycotoxin contamination is the largest concern in pet foods today. According to Smith,

“when half of the food is of vegetable origin, there will always be some degree of contamination. If the food is mainly of animal origin, the chances of contamination are greatly reduced.” 

#2 Antinutrients

Antinutrients are naturally occurring or man-made substances in food that can interfere with the absorption of vitamins, minerals and other nutrients, and interfere with digestive enzymes. In a nutshell, they can rob your dog of nutrition. Antinutrients are most commonly found in grains, beans, legumes and nuts.

bad foods for dogs

These include:

1. Phytic Acid (Or Phytate)

Phytic acid is found in grains and legumes (like peas, which are commonly found in grain-free pet foods). It’s an antinutrient because it can bind to important minerals such as copper, iron, magnesium and zinc, and make them unavailable to your dog. Phytic acid can rob your dog of up to 80% of these critical nutrients.

2. Lectins

Lectins are found in large amounts in beans and some grains and, like phytic acid, can also reduce nutrient absorption. But lectins can do more damage than that … they can damage the cells that line your dog’s intestines. When this happens, the ability of nutrients to be able to pass through your dog’s intestines and into his body are affected. It can also disrupt the delicate balance of flora living there and trigger allergy and autoimmune reactions.

There are many other antinutrients in grains and starches, including gluten (which can cause leaky gut syndrome and autoimmune disease), tannins (which can upset the gastrointestinal tract) and oxalates (which can cause kidney stones).

#3 Glycemic Load

glycemic load calculations

The glycemic load of foods is an indication of how quickly it raises the blood sugar. A small, steady amount of carbohydrate or starch in the diet is fairly harmless, but when large amounts of starchy carbohydrate are added to the diet (and most dry dog foods are 30-60% carbohydrate), this can cause obesity and insulin resistance.

Insulin is a hormone found in all humans, dogs and cats. One of insulin’s primary purposes is to get sugar from the blood into the cells. Insulin is the only hormone that does this.

On the other hand, your dog has multiple hormones that raise blood sugar … and this tells us a lot about the type of diet dogs are designed to eat. The body is much better prepared to raise blood sugar when carbohydrate is scarce, than it is to lower it when too much carbohydrate is eaten.

When your dog eats carbohydrates, they’re broken down into glucose, which is the form the body can use for fuel. When this happens, insulin is released to move the blood sugar, or glucose, into the cells. And how quickly this happens is the food’s glycemic load.

The only foods that cause a quick spike in glucose and insulin secretion are carbohydrates.

Why is spiking insulin unhealthy? Over time, the dog’s body will become less sensitive to insulin and insulin resistance can occur. And that’s bad because the pancreas will have to work harder to produce more and more insulin and can become exhausted … and your dog can develop diabetes.

But that’s not the only risk. Insulin resistance can also increase the risk of thyroid disease and some types of cancer. And because one of insulin’s jobs is to store body fat, the dog eating a lot of carbohydrate can become fat … and you’ll find it really hard to take the weight off.

Other Dangers Of Carbohydrate

There are 6 key reasons to avoid starchy carbs in your dog’s diet.

carbohydrates bad for dogs

Given this, you’d think most commercial pet foods would steer clear of carbohydrates. But they don’t!

Why Are Carbs In So Many Foods And Treats?

Why are carbohydrates in so many dog foods and treats?

They’re cheap.

Let’s face it, pet foods can be expensive and carbohydrates can provide energy without adding much cost. But because they’re so nutritionally incomplete, you’ll also see other ingredients added to dog foods to make up for the lack of nutrition in the carbs. So you’ll see:

dog food ingredients

  • Added vitamins
  • Added minerals
  • Added free amino acids (because carbohydrates are an incomplete source of protein)

But if budget isn’t as important as your dog’s health, there are some ways to reduce the carbohydrate load in your dog …

Cutting Back On The Carbs

Ready to cut the carbs out of your dog’s diet? Here are some solutions, listed in order from most desirable to least desirable …

1. Feed A Raw Diet

There’s nothing magical about raw diets … the only reason raw feeders see fewer health issues in their dogs is because they don’t contain starchy carbohydrates. Fruits and vegetables are fine … they don’t contain phytic acid, they have a low glycemic load and they can be loaded with vitamins and minerals. But raw diets are free of peas, potatoes and cereal grains and that’s why so many dogs do so well on them.

2. Cook For Your Dog

This is a tough one because so many cooked diets are loaded with carbohydrates. Fresh foods are always better than processed foods, so if you cook for your dog, try to keep the carbohydrates to less than 10% of the diet and load your dog up on protein and fat instead.

3. Feed A Low Starch Dog Food

Note that I didn’t say feed a grain-free diet. Grain-free diets can be higher in starch than regular foods … they just replace the grains with potatoes and peas.

What you’ll want to find is a food with the least amount of carbohydrate … and that means no more than 15%. The problem is, pet food manufacturers aren’t forced to tell you how much carbohydrate is in the food … so they don’t!

Fortunately, it’s pretty easy to calculate the amount of carbohydrate in your dog’s food.

pet food nutrition

Flip your bag of dog food over and you’ll find something called the Guaranteed Analysis. This is the guaranteed minimum amounts of certain nutrients in the food. Next, find the percentage of protein, fat, moisture and ash and then add them together.

If the ash content isn’t listed on the food, just use 7% for kibble and 2% for canned food. Ash content can vary but for most dry foods it typically ranges from 5% to 8%.

Subtract that total from 100 and that will give you the percentage of carbohydrate in the food. Here’s the math:

Let’s look at a couple of random examples … a regular dry food and a grain-free food (these are completely random and are not an endorsement of any kind).

Here is Fromm Gold Holistic Large Breed Adult Dry Dog Food


If you turn the bag over, you’ll find the Guaranteed Analysis. So let’s plug the numbers in.

100 – (23 (Protein) + 12 (Fat) + 10 (Moisture) + 7 (Ash)) = 48% Carbohydrate

Next let’s look at another food: Addiction Grain-Free Salmon Bleu Dry Dog Food.


Let’s see what the carbohydrate content is in this food:

100 – (24 (Protein) + 13 (Fat) + 10 (Moisture) + 10 (Ash)) = 43% Carbohydrate

You can see that both these foods are very high in carbohydrate. Again, you’ll want to keep your carbs under 15% (and if you start looking at foods, you’ll see that’s a very rare find).

What Happens If You Do Nothing?

The worst thing you can do is to keep doing what you’re doing because your dog “appears” to be healthy. Whether it be weeks, months or years from now, you and your vet probably won’t make the connection between his allergies, cancer, liver or kidney disease, and the lifetime of eating an unnecessary food that can cause very real health issues if it’s fed in excess.

If kibble is all you can afford, then try to add some protein or healthy fat (like hemp oil, eggs or whole fish) to your dog’s diet … at the minimum it will lower the glycemic load and replace some of the missing vitamins and minerals. But doing nothing is setting your dog up to fail.

Don’t rely on pet food companies to tell you what’s right for your dog … even the best companies have to care about their financial health before they can ever consider your dog’s health. Quality ingredients cost money and most dog owners aren’t prepared to pay that price for their dog’s food. Hopefully you’re an exception and you’ll start to see the connection between your dog’s health and the foods that you give him.