What Are the Best Ingredients for Cat Food? A Vet’s Guide to Feline Nutrition

Dry food is typically 6 to 10% moisture. Wet food is typically 70 to 80% moisture, per the Cornell Feline Health Center reference values. 

A cat fed mostly on wet food drinks meaningfully more water across the day than a cat fed mostly on dry food, even when both have a water bowl. Cats have a weak thirst drive compared to other species. They're designed to take water in with their food, not to drink it separately.

For cats specifically, hydration matters in three ways:

• Kidney load. Higher daily water intake takes pressure off the kidneys, which matters especially for cats already showing early kidney changes. Chronic kidney disease affects up to 40% of cats over 10 and 80% of cats over 15, making it the most common diagnosis we see in senior cats.
• Urinary mineral concentration. Concentrated urine makes it easier for crystals or stones to form. More dilute urine is less likely to cause problems.
• FLUTD risk. Feline lower urinary tract disease is one of the most common reasons cats end up at the vet. Diet moisture is one of the few changes you can make at home that consistently helps.

Vague Protein Sources: Unnamed terms like "meat meal", "animal by-product", or "animal fat" make quality and sensitivities hard to assess. Named sources like "chicken meal" or "deboned chicken" are better — especially for cats, whose sensitivities are often tied to a specific protein the label won't identify.

Artificial Preservatives: Avoid BHA, BHT (synthetic antioxidants flagged for long-term concerns) and ethoxyquin (a pesticide-derived preservative restricted in human food). Natural alternatives — mixed tocopherols (vitamin E), rosemary extract, ascorbic acid — appear in most reputable formulas.

Excessive Plant-Based Fillers: Corn gluten meal, soy protein isolate, and large amounts of pea protein inflate the crude protein number without the animal-source amino acids cats need. Some fibre is fine; the concern is when they dominate the ingredient list over named proteins.

Sugars, Propylene Glycol, and Artificial Colours: Propylene glycol damages cats' red blood cells and causes anaemia — hence the US FDA ban; check imported semi-moist products. Added sugars and artificial colours (Red 40, Yellow 5, Blue 2) add empty calories or appeal but no nutritional value.

Browse VLP's vet-recommended cat food collection for prescription and clinically formulated diets. These are the foods our vets reach for first when a cat needs more than a maintenance diet.

Stocked brands include Royal Canin Veterinary, Hill's Prescription Diet, Purina Pro Plan Veterinary, and Advance. The full range is in our vet-recommended cat food collection.

The best ingredient list depends on the cat in front of you. Age, indoor or outdoor status, body condition, and any underlying health condition all change the answer.

For deeper guidance on any of these profiles, see VLP's specific guides on kitten nutrition, senior cat food, urinary support, kidney support, and sensitive stomach feeding.

Cat food marketing is heavy on claims and light on evidence. Here's what the clinical literature actually says.

"Grain-free is better for cats"

Most cats tolerate grains like rice and oats without any issue, and true grain intolerance is rare in cats. The US FDA investigation that drove the grain-free conversation focused on dogs and a possible link to heart disease in breeds not previously predisposed. The underlying principle still applies to cats: a diet over-engineered around a marketing claim isn't automatically a better diet.

What matters for cats is overall ingredient balance and a high proportion of named animal-based ingredients, not the absence of grain.

"Dry food cleans cats' teeth"

Dry food is often marketed as helping clean a cat's teeth. Most dry kibble shatters easily on the first bite and does very little for the tooth surface. It doesn't effectively remove plaque or prevent dental disease in cats.

Dental disease in cats is best managed through regular tooth brushing, vet-formulated dental treats, or veterinary dental diets specifically designed to clean teeth at bite size.

"Cats need variety in their diet"

Many cats prefer consistency and do well on a stable, balanced diet. Frequent changes often lead to digestive upset or food refusal. The one specific case where variety helps is in kittens: introducing different textures, including both wet and dry, before 12 months of age can prevent fussiness later in life.

"Milk is good for cats"

Most adult cats are lactose intolerant. Cow's milk causes diarrhoea and digestive upset. Fresh water should always be the main source of hydration, supplemented by the moisture in your cat's food.

"More protein is always better"

Cats need high-quality, easy-to-use protein, not necessarily more of it. For senior cats with reduced kidney function, very high protein loads can put extra workload on already compromised kidneys. Phosphorus content matters just as much as protein content for cats with kidney disease risk, which is why veterinary renal diets contain controlled high-quality protein rather than restricted protein.

This is the opposite of the dog conversation, where high protein is often a safe default. For cats over 10, protein quality, phosphorus levels, and moisture matter more than the protein percentage on the front of the pack.