Is Grain-Free Cat Food Bad for Cats?

There is no evidence that grain-free cat food is bad for cats, and no evidence that it is better. "Grain-free" tells you one thing the food leaves out. It says nothing about how much meat is in the bag, what replaced the grain, or what it costs per month.

The 2018 heart disease reports were almost all about dogs: 515 dog reports and 9 cat reports by April 2019. The FDA later said reports like these cannot, on their own, show that a food caused the disease. The question that matters is what replaced the grain. That is what we score.

What "Grain-Free" Actually Changes on the Label

Kibble needs starch to hold its shape. Take out the corn, wheat or rice and something has to fill the gap. On most grain-free labels that something is peas, lentils, chickpeas, potatoes or tapioca. Those are carbohydrates too.

On our list grain-free foods still come out lower in carbohydrates on average: about 24%, against 30% for foods with grains. The range is wide, though. Wellness Complete Health Grain Free Indoor has peas and potatoes in its first five ingredients and works out to 34%, more than the average food with grains.

Most US labels do not list carbohydrates, so we estimate them: 100 minus protein, fat, fiber, ash and moisture. When the label gives no ash value, we assume 7%. The estimate is on every food page, and it is the number to check when a bag says grain-free. Watch for pea protein and potato protein too. They raise the protein percentage without adding meat, which is why our ingredient score gives them 2 points out of 5 and named meat 5.

The Heart Disease Question

In July 2018 the FDA announced that it was looking into reports of dilated cardiomyopathy (DCM), a disease where the heart muscle weakens, in dogs eating certain diets. Many of the foods named were grain-free and high in peas, lentils or potatoes. That is where "grain-free causes heart disease" came from.

Cats were barely in the data. Between January 2014 and April 2019 the FDA received 515 dog reports, covering 560 dogs, and 9 cat reports, covering 14 cats. The same page notes that cats are generally more likely to develop a different heart disease, hypertrophic cardiomyopathy. By July 2020 the totals were about 1,100 dogs and 20 cats, and the agency's work stayed on dogs. In December 2022 the FDA wrote that adverse event reports alone "do not supply sufficient data to establish a causal relationship," and that it would post no further public updates until there is meaningful new scientific information. Its questions and answers page notes reports linked to both grain-free and grain-containing diets. No cause has been named.

Cats have their own, older story. In 1987 researchers linked DCM in cats to a lack of taurine, an amino acid cats cannot make enough of; the heart muscle failure reversed when taurine was added. Today every food labeled complete and balanced for cats has to meet the AAFCO taurine minimum, grain-free or not. Nothing in the FDA data shows that grain-free food causes heart disease in cats. Nothing shows the opposite either, because cats were hardly studied. If you want to be careful, prefer grain-free foods whose first five ingredients are named meat rather than peas and lentils. Our ingredient score already rewards that.

Do Cats Need to Avoid Grains?

Most do not. A suspected allergy is one common reason people buy grain-free, and grains sit low on the list of foods cats react to. A 2016 review of published cases (Mueller, Olivry and Prélaud) covered 78 cats with an identified food allergen. Beef was involved in 18% of them, fish in 17% and chicken in 5%. Wheat, corn and dairy were 4% each.

Many grain-free foods are built around chicken or fish. Moving a cat from chicken and rice to grain-free chicken may not remove the ingredient it reacts to. If you suspect a food allergy, talk to your vet; the usual test is an elimination diet done under their guidance.

What Our Scores Show

Pettings gives no points for being grain-free. Each ingredient gets 0 to 5 points by what it is: named meat 5, fruits and vegetables 3, peas, potatoes, oats and brown rice 2, corn and wheat 1. The first five ingredients carry 70% of the ingredient score. A separate nutrition score checks protein, fat and estimated carbohydrates against our target ranges. How We Score has the details.

Even so, grain-free foods come out ahead on our list. Of 149 dry foods, 53 are grain-free. They average 72 on ingredients, against 49 for foods with grains, and 10 of our 10 highest scoring foods are grain-free. The reason is not the missing grain. It is what usually comes with it: more meat at the top of the label. Grain-free foods also cost more, a median of $4.55 per lb against $2.71.

A few foods from our list show the spread.

Orijen's label opens with chicken, turkey, whole herring, turkey giblets and salmon; lentils first appear at ingredient eleven, and its carbohydrate estimate is 20%. Blue Buffalo Wilderness also starts with meat, but pea protein, tapioca starch and peas fill places three to five, so it lands at 62, close to the grain-inclusive Hill's at 52.

The nutrition column tells a similar story. Wellness Complete Health Grain Free Indoor scores 8.3, with an estimated 34% carbohydrate, above our 15 to 25% range. Acana's Indoor Entree, which has grains, scores 9.6. Blue Buffalo Wilderness meets every nutrition range we use, but its label lists "fish meal" without saying which fish, and we lower the nutrition score when an ingredient's source is not named. Filter our list for grain-free and sort by nutrition to see the full order.

When Grain-Free Is Worth It, and When It Is Not

Grain-free is worth paying for when the grain was replaced with meat: named animal proteins in the first five ingredients and a carbohydrate estimate inside our 15 to 25% range. Orijen Original and Wellness CORE are clear examples. On our list 27 of the 53 grain-free foods have a carbohydrate estimate in that range, against 20 of the 96 foods with grains.

It is not worth paying for when the grain was replaced with peas, potatoes and pea protein. You get a similar amount of starch under a different name, often at a higher price.

Grain-free is not a treatment either. A cat with vomiting, itchy skin or weight loss needs a vet, not a different bag. If you are choosing between two bags, set the grain question aside and compare ingredient score, nutrition score and price per pound. Those tell you more.

Looking for a grain-free food that scores well without the top price? See the Cheapest Grain-Free Dry Cat Food With an Ingredient Score Above 80.

Sources

• US FDA, "FDA Investigation into Potential Link between Certain Diets and Canine Dilated Cardiomyopathy", first announced July 12, 2018; status report June 27, 2019 (515 dog and 9 cat reports covering 560 dogs and 14 cats, January 2014 to April 2019); update December 23, 2022.
• US FDA, "Questions & Answers: FDA's Work on Potential Causes of Non-Hereditary DCM in Dogs", content current as of August 19, 2024.
• American Veterinary Medical Association, JAVMA News, "FDA urges collaboration as dilated cardiomyopathy afflicts more dogs", December 9, 2020 (1,100 dog and 20 cat reports, January 2014 to July 2020).
• dvm360, "FDA targets peas, lentils, potatoes in investigation of grain-free diets and DCM", June 27, 2019.
• Mueller RS, Olivry T, Prélaud P (2016). "Critically appraised topic on adverse food reactions of companion animals (2): common food allergen sources in dogs and cats". BMC Veterinary Research 12, 9.
• Pion PD, Kittleson MD, Rogers QR, Morris JG (1987). "Myocardial failure in cats associated with low plasma taurine: a reversible cardiomyopathy". Science 237(4816), 764 to 768.
• AAFCO Cat Food Nutrient Profiles (protein, fat and taurine minimums), AAFCO Official Publication.
• Pettings, How We Score and Cat Food Questions. Scores, carbohydrate estimates and prices come from the food pages linked above and update when our data does.

The scores describe what the label says. They are not medical advice. If your cat has a health problem, talk to your vet before changing food.