Grain-free cat food: what the evidence says

If you have spent any time reading about grain-free pet food online, you have probably encountered the warning: the FDA investigated a link between grain-free diets and heart disease. That warning is repeated across pet forums, vet clinic blogs, and product reviews. It is also being misapplied to cats almost every time.

That mix-up matters. The cat side of the heart-disease question runs on a different and much older track, one the industry has largely already settled. Here is what the evidence actually says.

What grain-free actually means

Grain-free cat food contains no wheat, corn, rice, barley, oats, or other cereal grains. That is the whole definition. It does not mean low-carb, high-protein, or limited-ingredient. It just means no grains.

Kibble needs starch to form a stable extruded pellet, so grain-free kibble has to replace the grain with something else. In practice that means peas, lentils, chickpeas, potato, sweet potato, or tapioca. Wet and canned foods do not need that starch backbone, so they are often naturally lower in carbohydrate whether or not the label says “grain-free.”

If grain-free is the only thing you know about a food, you know less than you might think.

Do cats need grains?

No. Cats are obligate carnivores, which means their nutritional requirements are met by animal tissue and they have no biological need for grains, legumes, or any plant-based carbohydrate. We covered this in detail in Why your cat cannot just eat anything.

Cats can metabolise some carbohydrate, and small amounts are not harmful in a complete and balanced food. But unlike dogs and humans, cats have no dietary carbohydrate requirement. Whether the carbs in a kibble come from rice or from peas matters very little to the cat's nutrition. What matters is whether the food meets the cat's actual requirements for protein, taurine, arachidonic acid, preformed vitamin A, and the other nutrients only animal tissue reliably supplies.

So “grain-free” on its own does not make a food better or worse for a cat. It just describes one ingredient category that is not there.

The DCM investigation, and why it is a dog story

In 2018 the US Food and Drug Administration opened an investigation into a possible link between certain grain-free dog diets and dilated cardiomyopathy in dogs. The diets of interest were typically high in peas, lentils, and other pulses. The FDA published updates through 2019 and 2020, then a 2022 statement noting they had not been able to establish a causal relationship.

The investigation was about dogs. The reported cases were dogs. The diet patterns under examination were dog foods. Cats were not the focus, and the FDA's communications did not draw conclusions about cats.

This is the part that gets lost in translation. A warning that grain-free pet food might cause heart disease became a generic message applied to both species, when the underlying investigation was looking at one of them.

What about heart disease in cats?

Cats do get dilated cardiomyopathy. The cat version of the story is older and much better understood.

In 1987 a research team at UC Davis, led by Paul Pion DVM, identified taurine deficiency as the cause of DCM in domestic cats. Taurine is an amino acid that cats, unlike dogs and humans, cannot synthesise in adequate amounts and must obtain from their diet. Animal tissue is the natural source. Cats fed diets too low in taurine were developing DCM, and the disease was reversible when taurine was restored.

After that discovery, the pet food industry began supplementing taurine in complete and balanced cat foods, and AAFCO set a minimum taurine requirement for cat diets. Modern complete and balanced cat foods, grain-free or otherwise, supplement taurine. DCM from dietary taurine deficiency in cats is now uncommon.

This does not mean DCM in cats is impossible, only that the diet-driven version of it is something the industry addressed nearly forty years ago, and that addressing it had nothing to do with whether the food contained grains.

So is grain-free safer for cats? Worse? Neither?

The honest answer is that grain-free, by itself, does not tell you whether a cat food is good or bad. Quality runs across both kinds: there are excellent grain-free foods and mediocre ones, and the same is true of foods with grains. For cats specifically, the grain question is largely a marketing axis, not a nutritional one.

What the FDA investigation does suggest, cautiously, is that very high inclusion rates of pulses in extruded diets are worth keeping an eye on in dogs. There is no equivalent body of evidence suggesting the same concern in cats. If you want to be conservative you can avoid foods where the first several ingredients are pulses, but that is a precaution borrowed from a different species’ investigation, not a cat-specific recommendation.

What grain-free does not tell you

A “grain-free” claim says nothing about:

• Whether the named first ingredient is an animal protein
• The total protein percentage, or how much of it is plant-derived (pea protein, potato protein) versus animal-derived
• Whether the food is complete and balanced for your cat's life stage
• The carbohydrate level, which can still be high if pulses and potato make up the bulk of the recipe
• Whether the food uses synthetic preservatives, synthetic colours, or collective labelling like “meat and animal derivatives”

For more on reading what is on the label, see the Label Guide and Guaranteed Analysis Explained.

What to actually look for

For a cat food, grain-free or not, the things that matter are:

A named animal protein as the first ingredient. “Chicken,” “salmon,” or “lamb” tells you more than “meat” or “poultry by-product meal.”

A complete and balanced statement for the right life stage. In Australia look for compliance with AAFCO or the voluntary AS 5812 standard. Without this, the food is not guaranteed to meet your cat's nutritional requirements.

Transparency on the rest of the ingredient list. Specific named ingredients beat collective terms.

Protein that reflects animal sources. A grain-free food can pad its protein percentage with pea and potato protein. The first few ingredients tell you whether the protein is mostly animal.

If a grain-free food ticks those boxes, it is a reasonable choice. If a food with grains ticks those boxes, it is also a reasonable choice. The grain question is downstream of the questions that actually matter.

The Australian grain-free picture

In the KibbleGuide catalogue, the brands that lean grain-free across most of their range include Orijen, Ziwi Peak, Feline Natural, Frontier Pets, Trilogy, and Taste of the Wild. Applaws is mostly grain-free in its canned and pouch range. Several mainstream brands, including Royal Canin, Hill's Science Diet, Purina Pro Plan, and Advance, generally include grains in their cat formulations.

None of that ranks the brands. Plenty of grain-inclusive Australian cat foods are well-formulated, and plenty of grain-free ones are. The KibbleGuide brand pages and ingredient breakdowns will get you further than the grain-free claim on the front of the bag.

The bottom line

For cats specifically: grain-free is not a quality signal, not a health signal, and not a danger signal. The FDA DCM investigation was about dogs. Cat DCM is largely a taurine story that the industry resolved decades ago. Whether the carbohydrate in your cat's food comes from rice or from peas matters less than whether the food meets your cat's actual requirements as an obligate carnivore.

Choose on the basis of what is in the food, not what is missing from it.

Related reading

• Why Your Cat Cannot Just Eat Anything Peer-reviewed research on obligate carnivory and why cats do not need grains in the first place.
• Guaranteed Analysis Explained What the numbers on the label actually measure, and what they leave out entirely.
• The Label Guide How to read an Australian cat food label and what each ingredient term legally means.

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