Grain-Free Cat Food Pros and Cons — What It Is, Heart Disease Discussion & When It Makes Sense

Grain-free cat food: pros and cons. Grain-free food is one of the most talked-about labels in pet food, and one of the most misunderstood: it means the food contains no grains — no wheat, corn, rice, barley, or oats — and uses potatoes, sweet potatoes, peas, or lentils as the carbohydrate source instead. It does not mean the food is higher in protein, lower in carbohydrates, or better for your cat. This guide explains what grain-free food is, what its pros and cons are, what the veterinary discussion about it really says, and when grain-free food makes sense — and when it does not. No brand is recommended here, and no claim is made that grain-free food is better or worse in general: the answer depends on your individual cat.

The short version is: grain-free food is a reasonable choice for a cat with a diagnosed grain allergy, which is uncommon, and it is not a better choice for a cat without one. The evidence for the claimed benefits is limited, and there is an ongoing veterinary discussion about a possible link between grain-free diets and heart disease in cats that has not been settled. The rest of this guide explains both sides, so you can judge for yourself — and the judgement that matters most is your vet's, who knows your cat's health.

What grain-free food is — and what it is not

Grain-free food contains no grains, and it uses potatoes, sweet potatoes, peas, or lentils as the carbohydrate source instead. It is not carbohydrate-free: a grain-free food still contains carbohydrates, because the potatoes or peas that replace the grains are carbohydrates too, and the total carbohydrate content of a grain-free food is often similar to that of a food with grains. It is not necessarily higher in protein: some grain-free foods are higher in protein than foods with grains, and some are not — the protein level depends on the recipe, not on the absence of grains. And it is not necessarily more natural: potatoes and peas are no more natural for a cat than rice or oats, and the idea that grains are unnatural for cats is a marketing claim, not a nutritional one.

Grains are not fillers: wheat, corn, rice, barley, and oats supply energy, fibre, and nutrients, and they are used in pet food because they are digestible and nutritious, not because they are cheap. A food with grains can be complete and balanced, and a food without grains can be incomplete and unbalanced — the presence or absence of grains tells you almost nothing about the quality of the food. What matters is whether the food is complete and balanced, whether the manufacturer employs veterinary nutritionists and runs feeding trials, and whether it suits your individual cat. The how many calories should a cat eat per day guide gives the calorie tables for cats by weight, and the cat food calculator works out the daily amount for any food.

The pros of grain-free food

The clearest pro is for a cat with a diagnosed grain allergy: if your vet has diagnosed a grain allergy — by an elimination diet, not by a blood test, which is not reliable for food allergies — then a grain-free food is the right choice, because it removes the ingredient the cat cannot tolerate. True grain allergies are uncommon in cats: most food allergies in cats are to a protein, such as chicken or beef, not to a grain, and a cat that is itchy or has an upset stomach is more likely to be allergic to a protein than to a grain. But when a grain allergy is diagnosed, a grain-free food is the treatment, and it works.

The second pro is variety: a grain-free food gives an owner another option, and a cat that does not tolerate a particular grain can eat a food without it. The third pro is that some grain-free foods are well formulated, from manufacturers that employ veterinary nutritionists and run feeding trials, and they are good foods in their own right — not because they are grain-free, but because they are well made. A good grain-free food is a good food, and a bad food with grains is a bad food: the label is not the quality, and a grain-free label does not make a food good or bad on its own.

The cons of grain-free food

The first con is cost: grain-free food is usually more expensive than food with grains, and the extra cost buys no proven benefit for a cat without a grain allergy. The second con is the ongoing veterinary discussion about a possible link between grain-free diets and dilated cardiomyopathy, a heart disease, in cats — particularly in cats fed diets high in peas, lentils, and potatoes. Veterinary cardiologists have raised concerns about this possible link, and the evidence is not settled: the link has been reported in case studies and in veterinary practice, but it has not been proven, and it is not clear whether the cause is the absence of grains, the presence of peas and lentils, or something else in the diet. That uncertainty is itself a reason for caution, and it is a reason to talk to your vet before choosing a grain-free food, especially for a breed that is already prone to heart disease.

The third con is that grain-free food is often chosen for the wrong reason: an owner who believes grains are bad, or that grain-free means higher protein, or that a cat with an upset stomach must be allergic to grains, when the real cause is something else — a protein allergy, a sudden food change, or an illness. Choosing a grain-free food for the wrong reason delays the right diagnosis, and the cat keeps suffering while the owner tries food after food. If your cat is itchy, has an upset stomach, or has a skin problem, ask your vet to investigate it, rather than guessing at a grain-free food. The grain-free dog food pros and cons guide covers the same question for the other species.

When grain-free food makes sense — and when it does not

Grain-free food makes sense when your vet has diagnosed a grain allergy, by an elimination diet, and has recommended a grain-free food. It makes sense when a cat does not tolerate a particular grain, and a food without it suits the cat better — judged by the cat, not by the label. And it makes sense when the grain-free food is well formulated, from a manufacturer that employs veterinary nutritionists and runs feeding trials, and it is fed in the right amount for the cat's weight. In those cases, grain-free food is a reasonable choice, and it can be a good food.

Grain-free food does not make sense as a general choice for a cat without a grain allergy, because it costs more and buys no proven benefit, and because of the unresolved discussion about heart disease. It does not make sense as a treatment for an upset stomach, an itch, or a skin problem without a veterinary diagnosis, because those problems are more likely to be caused by something else. And it does not make sense as a way to feed a higher-protein diet, because grain-free food is not necessarily higher in protein — the protein level depends on the recipe, not on the absence of grains. If you are unsure, ask your vet: the vet knows your cat's health, and can tell you whether a grain-free food is right for it.

How to choose a grain-free food — if you do

If you do choose a grain-free food, choose it the way you would choose any food: look for a food labelled 'complete and balanced' for the cat's life stage, from a manufacturer that employs veterinary nutritionists and runs feeding trials. Check the ingredient list, but judge the food by the label, the manufacturer, and your cat — steady weight, a good coat, firm stools, and a vet who is happy at the annual check. Feed it in the right amount for the cat's weight, worked out from the RER formula, and measure it with scales. And tell your vet that the cat is eating a grain-free food, so the vet can watch for the signs that matter — especially heart health, in a breed that is prone to heart disease.

Do not choose a grain-free food by the front of the bag, and do not assume that a grain-free label means the food is better. Do not switch to a grain-free food suddenly — change foods gradually over a week, mixing the old and new in increasing proportions, so the cat's digestion can adjust. And do not keep switching foods: choose a food, feed it for at least a month, and judge it by the cat. The how to switch cat food safely guide explains how to change foods gradually, and the best food for indoor cats guide explains how to choose a food in general.

For related reading, see the grain-free dog food pros and cons guide, the how to switch cat food safely guide, the how many calories should a cat eat per day guide, the cat food calculator, the best food for indoor cats guide, the cat feeding chart by weight guide.

Frequently asked questions

Is grain-free food better for cats?

Not in general. Grain-free food is a reasonable choice for a cat with a diagnosed grain allergy, which is uncommon, but it is not better for a cat without one: it is not necessarily higher in protein or lower in carbohydrates, and it costs more. What matters is whether the food is complete and balanced and whether it suits your individual cat.

Is grain-free food linked to heart disease in cats?

Veterinary cardiologists have raised concerns about a possible link between grain-free diets — particularly diets high in peas, lentils, and potatoes — and dilated cardiomyopathy, a heart disease, in cats. The evidence is not settled: the link has been reported but not proven, and it is not clear what causes it. Talk to your vet before choosing a grain-free food, especially for a breed prone to heart disease.

Do cats need grains?

No — cats do not need grains specifically, but grains are a useful source of energy, fibre, and nutrients, and they are not fillers. A cat can do well on a food with grains or without them, as long as the food is complete and balanced. The presence or absence of grains tells you almost nothing about the quality of the food.

Are most food allergies in cats caused by grains?

No — most food allergies in cats are to a protein, such as chicken or beef, not to a grain. True grain allergies are uncommon. If your cat is itchy or has an upset stomach, ask your vet to investigate it, rather than guessing at a grain-free food.

Is grain-free food higher in protein?

Not necessarily. Some grain-free foods are higher in protein than foods with grains, and some are not — the protein level depends on the recipe, not on the absence of grains. Check the label for the protein level, and judge the food by whether it is complete and balanced and whether it suits your cat.

Should I switch my cat to grain-free food?

Only if your vet has diagnosed a grain allergy, or if a grain-free food suits your cat better — judged by the cat, not by the label. For a cat without a grain allergy, grain-free food costs more and buys no proven benefit, and there is an unresolved discussion about heart disease. Ask your vet before switching.

Results on this page are estimates for general information only and are not veterinary advice. If your pet is ill, underweight, overweight, pregnant, or has a health condition, consult your veterinarian before changing diet or care.