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Is Grain-Free Dog Food Harmful to Dogs?

Posted: 07/23/2022 | BY: Erin Cain | Categories: Dog , Pet care

Over the last five years, there has been considerable debate surrounding grain-free dog food. Some pet parents swear by it, while others believe it harms dogs. So, what’s the truth? Is grain-free dog food harmful to dogs? In this blog post, we’ll look at the current controversy surrounding grain-free food and help you decide whether or not it’s right for your pup.

What is grain-free dog food?

Grain-free dog food doesn’t contain carbohydrates such as corn, barley, rice, oats, soy, rye, and wheat. Dogs need carbohydrates as part of their nutrition, as carbs supply the body with energy, and the fiber within promotes healthy digestion. Also, grains contain essential fatty acids like linoleic acid and proteins necessary for a healthy canine. A grain-free dog food replaces these carbs with alternative carb sources, such as legumes, pea flour, and potatoes. 

Grain-free dog food initially became popular in 2007 due to a series of dog food recalls. Those traditional diets caused kidney failure and other serious health issues in several dogs. Dog parents became much more invested in the ingredients in their pup’s food, with grain-free foods advertised as a much healthier option than traditional kibble. Thus, the grain-free dog food industry was born, and over the last fifteen years, many pup parents have chosen grain-free foods for their pups.

What is the recent cause for concern with grain-free food?

In 2018, veterinary cardiologists notified the FDA of an increase in dogs with dilated cardiomyopathy (DCM). This heart condition decreases the heart’s ability to pump blood to the rest of the body. Ultimately, the state leads to heart failure. Breeds without any known genetic predisposition suddenly received this diagnosis, so veterinary researchers began investigating what was causing this sudden trend. 

Between January 2014 and April 2019, the FDA studied over 500 reports of DCM in dogs. Part of the investigation examined the dogs’ diets, and the results showed that 90% of affected dogs were eating grain-free food. Of that group, 93% ate food that contained lentils or peas. After testing the foods, the FDA found no abnormalities in the ingredients. This discovery led them to conclude that grain-free diets may be causing the higher rates of DCM in dogs.

Why might grain-free dog food be harmful to pups?

Indeed, grains, starches, or grain substitutes like legumes are usually processed commercially when dog food is produced. None of these ingredients truly belong in a carnivore’s diet. But what do some pet owners and animal researchers object to about grain-free food? Here are some current concerns with this diet:

Low-quality starches: 

Starches are not in grain-free foods because they are nutritionally valuable. The starches, including sweet potatoes and green peas, are used as cheap ingredients that bind kibble together during the cooking process.

Unfortunately, these low-quality starches are highly inflammatory in some canines as they are not biologically appropriate. They add unnecessary calories to the food, which may lead to obesity over time. Research shows starches may be responsible for skin conditions, gastrointestinal disorders, and other canine health issues.

Low-quality proteins:

While soy is a popular protein source for many people, it’s not the best choice when your dog needs nutrients. Dogs can have trouble digesting and processing this highly processed and often genetically modified. Plant-based food could lead to health problems. Other low-quality proteins in grain-free foods, like beans and peas, are overly high in starch.

Although dogs can digest plant materials, as carnivores, that doesn’t necessarily mean that they should as part of an everyday diet.

Genetically-modified organisms (GMOs)

The use of genetic engineering in the production and consumption of food has been steadily on the rise, and that is no different in our pets’ foods. Although GMOs are grown to be more resistant to herbicides, insects, and viruses, they can negatively impact the nutritional quality and value of the food.

For some dogs, GMOs cause inflammation and food sensitivities. Studies have linked them to organ damage, allergies, digestive disorders, immune system diseases, cancers, and cognitive issues in canines. 


Lectins are carbohydrate-binding proteins in plants that can be toxic to humans and animals. These proteins are a natural defense system for plants, and they cause illness in some people and pets that consume them.

Lectins are responsible for inhibiting the absorption of vital nutrients, including iron, zinc, and calcium, as they interfere with the body’s digestive enzymes. They are also known to cause inflammation within the body.


One of the most controversial aspects of human and pet food processing is the inclusion of glyphosate, an herbicide commonly known by its brand name, Roundup. Glyphosate is sprayed on soybeans and corn genetically engineered to withstand the herbicide. Recent FDA studies found that 63% of corn and 67% of soybean samples had glyphosate. While some scientists argue that glyphosate is relatively harmless to people, others, including the World Health Organization (WHO), view it as a cancer-causing carcinogen.

Glyphosate causes autoimmune diseases and allergies and damages the kidney lining, leading to kidney disease. Damage to the immune system and mucous membranes leads to leaky gut and inflammatory bowel disease (IBD). It’s little wonder that glyphosate is a cause for concern in grain-free dog food.

The grain-free dog food and heart disease connection

Although it’s still a working theory, researchers have noted a connection between DCM and canine heart disease and grain-free dog food that lacks appropriate levels of taurine. This amino acid metabolizes fats and is necessary for heart health in people and cats. However, dogs are usually able to make taurine themselves indirectly through diet. Taurine also plays a vital role in the immune system, brain, and eye functions. 

Taurine is found in meat abundantly. Unfortunately, some dogs, especially large breeds like Great Danes, Dobermans, and Retrievers, seem to have difficulty manufacturing taurine if they eat a diet low in animal proteins. Until 2020, the taurine deficiency theory was considered the potential link between the higher rates of DCM in dogs on grain-free diets.

The Journal of Animal Science published a peer-reviewed research article in summer 2020 that disputes the DCM-grain-free food connection. The authors argue that, despite the previous FDA study, their research establishes no definitive link between grain-free diets and DCM. The researchers claim that the FDA and subsequent studies around this subject may be influenced by sampling bias. Without actual evidence, the link in question is without merit. 

So is grain-free dog food safe for dogs, or not?

Currently, there is no proven scientific evidence that grain-free food will cause heart disease in dogs. That doesn’t necessarily mean it is safe or appropriate for every dog — like people, some dogs require specialized diets for various reasons. As the Journal of Animal Science states, more careful analysis and further study must occur before anyone can say grain-free food is terrible for all canines. 

That said, the FDA’s study was distributed to the veterinary community, and out of a preponderance of caution, many vets are discussing grain-free canine diets with pet parents and the possibility of the heart disease connection.

Talk with your veterinarian or a canine nutritionist if you have concerns about your dog’s grain-free diet. They can help you to determine whether you should be worried and what diet your dog should consume daily. For some pups, a fresh or raw food diet may be medically necessary and biologically appropriate.

Many pet foods — grain-free or not — are processed in kibble form, which has its nutritional drawbacks. Many human foods are the same. Perhaps the best approach dog parents can take is to speak with their vet, avoid being swayed by advertising and veterinary nutrition influencers, and do their homework on their dog’s food ingredients.

Let pet insurance help cover future canine illnesses.

A pet insurance policy for your pup is a smart purchase in the long run. Should your dog develop heart disease or another medical condition in the future, your dog’s health insurance plan will reimburse you for up to 90% of veterinary costs. That’s not only a lifesaver for your finances but also your dog’s longevity. 

Get a free, personalized quote from Pet Insurance Review for your dog so you can protect your pup now and in the future.


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  3. FDA. (2019). FDA Investigation into Potential Link between Certain Diets and Canine Dilated Cardiomyopathy. Retrieved from
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  7. Hannaby, L. (2021). Lectins and Should My Dog Eat Them? Retrieved from
  8. Thixton, S. (2015). Herbicide Glyphosate Found In Pet Foods. Retrieved from
  9. White, P. (2021). Grain Free Diets, Taurine Deficiency, and Heart Disease – What’s the Story? Retrieved from
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The information contained on this blog is intended for informational and educational purposes only and should not be construed as medical advice. It is not a substitute for professional veterinary care. Always consult with your veterinarian before making any changes to your pet's health care or treatment plan.

The authors of this blog are not veterinarians and do not claim to be experts in pet health. The information provided here is based on our own experiences and research, as well as information from reputable sources. However, we cannot guarantee the accuracy or completeness of this information.

We encourage you to do your own research and consult with your veterinarian before making any decisions about your pet's health.

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