Vets: Grain-free pet foods no healthier

Losing weight is tough. It would be easier if a benevolent someone concerned about your health controlled exactly how much you ate and how often you exercised, right? That’s the situation for most dogs and cats in the United States, and yet the majority are overweight or obese.

As with our own dieting woes, the unpleasant prospect of the simple solution — feeding our furry friends less — makes us reach for alternative, quick-fix strategies. Many pet parents have turned to radically new menus. These grain-free, all-meat and raw-food diets are inspired by the meals eaten by their wild relatives.

But are these diets really better for our pets? Veterinarians and researchers say probably not.

According to clinical veterinary nutritionists at Tufts University, grain-free foods were one of the fastest-growing sectors of the pet food market in 2016. “All I ever hear is, oh, on a good diet, it’s grain free,” said Dena Lock, a veterinarian in Texas. The majority of her pet patients are overweight.

Why have these pet diets become so popular?

“It’s a marketing trend,” Lock said.

“Grain-free is marketing. It’s only marketing,” said Cailin Heinze, a small-animal nutritionist at Tufts University’s Cummings School of Veterinary Medicine. “A lot of foods market themselves by what they’re not including,” and the implication is that the excluded ingredient must be bad.

“Grain-free is definitely a marketing technique that has been very successful,” said Jennifer Larsen, a clinical nutritionist at the University of California Veterinary School in Davis. People think that if they pay a lot for food and there are a lot of exclusions on the bag, that the food is healthier, but “they’re buying an idea,” she said, “not necessarily a superior product.”

There is no data to support the idea that grain-free diets are better for pets, Heinze and Larsen noted.

Some pet owners have a false impression that grains are more likely to cause an allergic reaction, but “it’s much more common for dogs to have allergies to meat than to grain,” Heinz said. Chicken, beef, eggs, dairy and wheat are the most common allergies in dogs. It’s not that there’s anything particularly allergenic about these foods, she said, they’re just the most frequently used ingredients.

Marketing campaigns such as Blue Buffalo’s Wilderness or Chewy’s Taste of Wild claim their grain-free, meat-forward formulations better reflect the ancestral diets of our dogs’ and cats’ evolutionary predecessors, but the veterinarians I spoke with questioned this.

Our pets’ wild cousins aren’t that healthy. “People believe that nature is best,” Larsen said, but “animals in the wild don’t live that long and they don’t lead very healthy lives.” For dogs, we know that they have diverged from wolves genetically in their ability to digest starches. “Dogs aren’t wolves,” said Robert Wayne, a canine geneticist at UCLA. “They have adapted to a human diet.”

Research in Wayne’s lab showed that most wolves carry two copies of a gene involved in starch digestion, while dogs have between 3 and 29 copies. According to Heinze, the average dog can easily handle 50 percent of its diet as carbs.

For cats, this argument makes a little more sense. Cats are carnivores rather than omnivores, so they have higher protein requirements than dogs, but “cats can digest and utilize carbohydrates quite well,” said Andrea Fascetti, a veterinary nutritionist at the University of California Veterinary School in Davis.

Many grain-free pet foods are made with starch from potatoes or lentils and they may be higher in fat. If you cut grains but increase calories, your pet is going to gain weight, Heinze said.

Dogs and cats also have a drastically different lifestyle from wolves or tigers. Pets are almost always spayed and neutered which is in itself a risk factor for obesity. And most live inside or in yards, so their energy needs are reduced.

In the wild, wolves and feline predators eat the hair, bones and cartilage of their prey, not just meat. For pet owners who do choose to feed their animals an all-meat diet, it’s essential to add supplements to make sure their pet isn’t missing out on key nutrients such as calcium, Fascetti said. And there’s the environmental impact to consider: Pets consume a quarter of all animal-derived calories in the United States.

Experts caution against feeding pets raw meat. “It’s not uncommon to find things like salmonella and E. coli and listeria in raw meat,” Larsen said. There are a lot of microbes present in farming systems, and unlike when an animal is in the wild, there are many opportunities for bacteria to contaminate meat between the time an animal is slaughtered and when it reaches our kitchens.

Even if eating contaminated meat doesn’t make pets sick, it poses a health risk to pet owners and their children who handle the pet food and waste. The Centers for Disease Control and Prevention and the Food and Drug Administration both warn against feeding raw meat to your pets. “I really can’t advocate it, because it’s not safe for the whole family,” Heinze said.