Can Cats Digest Grains? | What Science Actually Says

Yes, cats can digest processed grains efficiently — properly cooked grains are well-tolerated and provide valuable nutrients as part of a balanced diet.

If you’ve wondered whether cats can digest grains or heard conflicting claims about grain-free diets, you’re not alone. The debate has fueled a $12 billion grain-free pet food industry built on a misconception: that cats, as obligate carnivores, cannot handle carbohydrates. But decades of research tell a different story. Domestic cats have adapted to digest processed starches at rates exceeding 95%, and the real nutritional question isn’t whether grains are digestible — it’s which ones work best and how they’re prepared.

The Short Biology: Why Cat Digestion Is Different

Cats are obligate carnivores, meaning their bodies evolved to get nutrients primarily from animal tissue. Unlike dogs or humans, cats lack salivary amylase (the enzyme that starts starch breakdown in the mouth) and have low pancreatic amylase activity. This makes whole, unprocessed grains harder to digest. However, modern cat food manufacturing — specifically the grinding and cooking that happens during extrusion — breaks down starch molecules enough for cats to absorb them efficiently. Studies show domestic cats can digest more than 95% of starches when grains are properly processed, with digestibility ranging from 40% to 100% depending on the grain type and cooking method.

Which Grains Can Cats Actually Digest?

Not all grains are equal in a cat’s digestive system. Research published in the Journal of Animal Science and PMC databases has measured digestibility differences between grain types, and the results show clear winners and losers.

Key takeaway: corn gluten meal and properly processed grains like rice and wheat are highly digestible. Whole grains — especially whole rice — are less digestible and can actually reduce protein absorption. That’s why quality cat foods always use processed grain ingredients.

Is Grain-Free Cat Food Actually Healthier?

The short answer is no — not for healthy cats. Multiple veterinary sources, including PetMD’s grain-free cat food comparison, note that grain-free diets are not inherently healthier than grain-inclusive diets. The misconception stems from the idea that grains are “fillers” — but they actually provide B vitamins, iron, calcium, and energy. Grain-free foods swap grains for peas, potatoes, or sweet potatoes, which often have similar or higher carbohydrate content. A grain-free label does not mean low-carb.

How to Safely Include Grains in Your Cat’s Diet

Feeding grains to cats comes down to three rules: processing, portion control, and label verification.

• Always use processed grains. Raw or whole grains are difficult for cats to digest and may cause digestive upset. Stick with cooked, ground, or extruded grains found in commercial cat food.
• Keep treats under 10% of calories. If you’re giving your cat a piece of toast or a bite of cooked rice, ensure treats and supplemental foods don’t exceed 5–10% of the total diet. The other 90% must come from a complete and balanced cat food.
• Check the label. Look for the AAFCO statement confirming the food is “complete and balanced” for your cat’s life stage. Foods tested through feeding trials are ideal.

For a curated selection of high-quality options, check out our tested roundup of the best grain-inclusive cat foods — each one meets these guidelines.

Grain-Free vs. Grain-Inclusive: What’s Different?

Many owners choose grain-free thinking it’s closer to a cat’s ancestral diet. But modern domestic cats have evolved differently from their wild ancestors. A 2017 review in PMC highlighted that domestic cats have genetic adaptations for starch digestion that wild felids lack. The real difference between the two diet types is often just the carbohydrate source — grains vs. legumes and tubers — not the total carbohydrate level.

Here’s how they compare for healthy adult cats:

The bottom line: for the vast majority of cats, grain-inclusive diets are nutritionally adequate, more affordable, and just as digestible as grain-free alternatives.

When Should You Choose Grain-Free?

Grain-free diets serve a medical purpose — but only for a small subset of cats. The primary reasons include:

• Documented food allergy or intolerance: True grain allergies in cats are rare, but they do exist. If your vet confirms an allergy through an elimination diet, grain-free is warranted.
• Inflammatory bowel disease (IBD): Some cats with IBD respond better to limited-ingredient or grain-free diets.
• Other inflammatory conditions: Your veterinarian may recommend a specific grain-free therapeutic diet.

For cats without these conditions, grain-free diets offer no proven health advantage and may come with downsides — including higher cost and inconsistent protein quality.

Final Guidelines: Grains in Your Cat’s Bowl

Here’s what to remember when choosing whether to feed grains:

• Cats digest processed grains well — up to 95%+ starch utilization when cooked.
• Corn gluten meal and processed rice outperform whole grains in digestibility.
• Grain-free does not mean low-carb or healthier.
• Treats should stay under 10% of total calories.
• Always choose complete and balanced foods for your cat’s life stage.
• If your cat has no diagnosed grain allergy, grain-inclusive food is a perfectly healthy choice.