Grain free dog food: the real pros and cons

January 27, 2026

Grain-free dog food went from niche health-food-store product to one of the best-selling categories in pet food in about a decade. By 2018, grain-free formulas accounted for roughly 44% of all dog food sold in specialty pet stores, according to market data from Nielsen. Then the FDA stepped in with an investigation, and suddenly everyone was confused.

I get asked about grain-free more than almost any other feeding topic. People want a straight answer: is it good or bad? The honest answer is more complicated than either camp wants to admit.

Where the grain-free trend came from

The idea behind grain-free dog food borrows heavily from human health trends, specifically the popularity of low-carb and paleo diets. The argument goes: wolves don't eat wheat, so dogs shouldn't either. Dogs are closer to their wild ancestors than we think, so grains are an unnatural addition to their diet.

There's a kernel of truth buried in there (no pun intended). Dogs are facultative carnivores who evolved eating primarily meat. But domestic dogs aren't wolves. A 2013 study published in Nature identified 36 genomic regions that differ between dogs and wolves, and 10 of those involve starch digestion and fat metabolism. Dogs have more copies of the AMY2B gene, which produces amylase for digesting starch. They literally evolved to eat grains alongside humans.

That doesn't mean grains are required. It means dogs can digest them just fine, which undermines the central marketing claim of most grain-free foods.

The actual pros

There are legitimate reasons to feed grain-free, though they apply to fewer dogs than the marketing suggests.

Some dogs have genuine grain allergies or sensitivities. Food allergies in dogs are real but less common than people assume. A 2016 review in BMC Veterinary Research analyzed 297 dogs with confirmed food allergies. The most common allergens were beef (34%), dairy (17%), chicken (15%), and wheat (13%). So wheat allergy exists, but it's the fourth most common food allergen in dogs, behind three protein sources. Rice and corn allergies were even rarer.

If your dog has been through a proper elimination diet with your vet and grains turned out to be the problem, grain-free food is the obvious solution. No argument there.

Some grain-free foods are higher in protein and use higher-quality ingredients than their grain-inclusive counterparts in the same price range. This isn't inherent to being grain-free, though. It's a side effect of grain-free brands positioning themselves as premium products.

Dogs with specific digestive conditions sometimes do better on certain grain-free formulas. Again, this should be diagnosed and monitored by a vet, not guessed at based on internet forums.

The cons (and the FDA investigation)

In July 2018, the FDA began investigating reports of dilated cardiomyopathy (DCM) in dogs eating grain-free diets. DCM is a serious heart condition where the heart muscle weakens and can't pump blood effectively. It had been showing up in breeds not typically prone to the condition.

By 2019, the FDA had received over 500 reports. The diets involved tended to share certain characteristics: they were grain-free, they listed legumes (peas, lentils, chickpeas) or potatoes as primary ingredients, and many came from smaller manufacturers without board-certified veterinary nutritionists on staff.

Here's the tricky part: the FDA investigation didn't establish a definitive cause. They found a correlation, not causation. The mechanism isn't clear. Some researchers suspect that legume-heavy diets interfere with taurine absorption (taurine deficiency is a known cause of DCM). Others think it might be related to the overall nutrient profile of these diets. A 2020 study from Tufts found that some grain-free diets had lower levels of certain amino acids, but not all did.

The investigation remains open. The FDA hasn't recalled any grain-free foods or told people to stop feeding them. But most veterinary nutritionists now take a cautious stance: unless your dog has a diagnosed grain allergy, grain-inclusive food is the safer default.

What grains actually do in dog food

Grains aren't filler, at least not good ones. Whole grains like brown rice, oatmeal, and barley provide digestible carbohydrates for energy, dietary fiber for gut health, and B vitamins. They also provide a calorie source that's less expensive than animal protein, which is why they've been in dog food since the beginning.

When a food removes grains, something has to replace them. Usually it's legumes (peas, lentils, chickpeas), potatoes, or sweet potatoes. These aren't bad ingredients on their own. But when they make up 30-40% of the formula (as they do in many grain-free foods), you're getting a diet that's still carb-heavy, just with different carbs. The "grain-free = low-carb" assumption doesn't hold for most commercial grain-free kibble.

Some grain-free dry foods actually have more total carbohydrates than grain-inclusive options. The only way to truly reduce carbs is to feed wet food, raw, or a fresh-cooked diet.

The cost difference

Grain-free food generally costs 15-40% more than comparable grain-inclusive formulas. Part of this reflects ingredient costs (legumes and potatoes can be more expensive in the quantities needed). Part of it is branding. The "grain-free" label signals premium, and companies price accordingly.

If you're feeding grain-free because you believe it's healthier for a dog with no grain sensitivity, you're paying a premium for a dietary change that probably isn't helping and might (per the FDA's ongoing investigation) carry some risk.

How to decide for your dog

Feed grain-free if your dog has a vet-diagnosed grain allergy or intolerance confirmed through an elimination diet. That's the clearest use case.

Consider grain-inclusive if your dog has no issues with grains. This is the position of the American College of Veterinary Internal Medicine, the World Small Animal Veterinary Association, and most board-certified veterinary nutritionists. It's the lower-risk option given current evidence.

If you're currently feeding grain-free and want to switch, do it gradually over 7-10 days by mixing increasing proportions of the new food with the old. Sudden switches cause digestive upset regardless of the food quality.

Either way, the quality of the overall formulation matters more than the presence or absence of grains. Look for foods made by companies that employ veterinary nutritionists, conduct feeding trials, and publish their nutrient profiles. AAFCO-compliant is the minimum, not the standard to aim for.

My take

The grain-free trend got way ahead of the science. Most dogs don't need it, the benefits are overstated for dogs without grain allergies, and the potential DCM connection (even if unproven) is reason enough to default to grain-inclusive for most dogs. If your dog is doing well on grain-free food, don't panic. But if you're choosing a new food and your dog doesn't have a diagnosed grain issue, I'd go grain-inclusive and spend the savings on better-quality protein.