Do Cats Need Vitamins or Supplements?

Most cats don't need vitamins. A healthy cat eating a complete and balanced cat food already gets the vitamins and minerals it needs. The Cornell Feline Health Center, the ASPCA and WSAVA all say a supplement is usually unnecessary on that diet.

More can even do harm. Below: how to check that your cat's food is complete, when a vet might suggest a supplement, and how to choose one if you use it.

What do vitamins actually do for a cat?

Vitamins are tiny helpers. The ASPCA describes them as catalysts for enzyme reactions. In tiny amounts, they support normal metabolic function.

Cats need some of them in a form other animals don't. Here's the surprising part: a cat can't turn beta-carotene, the orange pigment in carrots, into vitamin A.

The Merck Veterinary Manual explains that cats lack the gut enzyme to make that conversion. Their vitamin A has to arrive ready-made, from sources such as liver, fish oil or added vitamin A.

Niacin, one of the B vitamins, is similar. Merck notes that cats can't make meaningful amounts of it from the amino acid tryptophan, so their whole requirement has to come from food. Dogs can manage both conversions.

And there's one vitamin cats don't need to eat at all. According to Merck, dogs and cats make their own vitamin C from glucose in the liver.

So a cat food has to be built for cats. When the food is complete and balanced, that work has already been done.

What does "complete and balanced" mean?

It's the phrase that answers most of this question. AAFCO defines "complete" as containing all the nutrients required, and "balanced" as having them in the correct ratios.

The FDA explains that a food with this claim is intended to be fed as a pet's sole diet. To make it, the food must either meet one of AAFCO's cat food nutrient profiles or pass a feeding trial run under AAFCO procedures.

You'll find the claim in the nutritional adequacy statement, usually in small print on the bag or can. AAFCO calls it the key to meeting a pet's nutritional needs, and Cornell notes that foods carrying it are considered nutritionally complete and balanced.

Check the life stage too. AAFCO's life stages are growth (kittens), adult maintenance, pregnancy and nursing, and all life stages.

A product marked "for intermittent or supplemental feeding only" is a different thing. AAFCO uses that wording for treats and supplements, which are meant to be fed in addition to a complete diet.

What about kitten vitamins?

Kittens do need more. Merck's kitten care guide says growing kittens need extra calories, fat, protein, vitamins and minerals for rapid growth.

That extra comes from the food. Merck recommends a balanced kitten diet until adulthood, at about 9 to 12 months. Our guide to what to feed a kitten covers how to choose one and how much to give.

Can a cat get too many vitamins?

Yes, and it's the main reason vets are cautious. Cornell puts it plainly: more is not always better, particularly with vitamins and minerals.

The ASPCA warns that over-supplementation can poison a cat with some key vitamins and minerals. AAFCO adds that supplementing a complete and balanced diet risks exceeding the upper limits of certain nutrients.

Not every vitamin carries the same risk. Merck explains that water-soluble vitamins have much less potential for harm than fat-soluble ones, because excess is not readily stored in the body.

Vitamin A

Too much vitamin A is the best-known example in cats. Merck links it to diets that include a large quantity of liver, and notes it is seen more often in growing kittens fed a liver-heavy diet.

The excess causes bony outgrowths on the vertebrae that interfere with normal movement. Merck states that some signs may reverse if the diet is corrected early, but the skeletal changes are generally permanent.

Liver does have a place. Merck lists it as one of the normal sources of vitamin A for cats. The problem it describes is a diet with a large quantity of liver.

Vitamin D

Here's a second surprise. Merck notes that dogs and cats have very limited amounts of the skin compound that sunlight turns into vitamin D.

Too much is serious. Merck states that excess vitamin D raises calcium and phosphorus in the blood and can leave permanent mineral deposits in soft tissues.

AAFCO singles out vitamin D as having a fairly small gap between what's needed and what's toxic, especially in dogs.

When might a vet recommend a supplement?

There are real reasons, and they're specific. The ASPCA's position is that a vitamin or mineral supplement is unnecessary on a complete and balanced diet unless a vet diagnoses a specific deficiency.

Homemade food is the other common case. Cornell notes that a home recipe may not contain the right amounts and proportions of nutrients. Merck advises against formulating one on your own and suggests working with your vet and, ideally, a veterinary nutritionist.

WSAVA names one possible exception for cats on commercial food: essential fatty acids. Longer-coated breeds of cats and dogs may need slightly higher intakes for skin and coat quality, it says.

For those cats, WSAVA suggests a fatty acid supplement or a change of food may help. Our guide to omega-3 for cats looks at the evidence.

In each case the vet chooses the product and the amount for that cat. AAFCO advises owners to use the vet-prescribed dosage and follow the directions.

If you do use one, how do you choose?

Start with a conversation. Merck's advice to cat owners is short: don't give supplements without your vet's approval. Cornell says the same, and WSAVA adds that supplements need careful evaluation for safety and effectiveness.

• Choose a product made for cats, and keep your own vitamins out of reach. Merck notes that pets eating human vitamins is common, and some contain ingredients toxic to animals, such as xylitol.
• Read the whole label. If a product adds vitamin A or D, ask your vet whether your cat's food already supplies enough.
• Give the amount on the label or the amount your vet sets, and no more.

If you and your vet decide a daily extra suits your cat, it sits alongside a complete diet and never replaces it.

Choolip's Total Balance is one example: a lickable stick made with tuna, cod, salmon and lobster, fortified with vitamins A, B2, B3 and E, iron, zinc and a postbiotic.

It's a food supplement, not a complete diet, and a cat on complete food doesn't need it. Because it contains vitamin A, mention it to your vet along with anything else your cat takes.

How are pet supplements regulated?

Differently from human ones. The FDA states that products sold as dietary supplements for animals don't fall under DSHEA, the law that covers human supplements. It regulates them as either food or animal drugs, depending on their makeup and intended use.

Animal food doesn't need FDA review before it goes on sale.

A product that claims to treat or prevent disease is regulated as a drug and needs FDA approval, so a supplement making that kind of claim is a reason to ask your vet before buying.

What if my cat gets into vitamins?

Call your vet straight away. Merck's toxicology chapter notes that signs of vitamin D poisoning can appear within 12 to 48 hours of a large exposure.

Call your vet promptly if your cat:

• has eaten a human vitamin or supplement, or more of a pet one than the label allows
• is throwing up, drinking or peeing more than usual, or seems unusually quiet or low after taking any supplement
• has been eating a diet made mostly of liver
• starts moving stiffly

Questions new cat parents ask

Do kittens need vitamins?

Not as a separate product. Kittens need more vitamins and minerals than adults, and a complete and balanced food labeled for growth or all life stages is formulated to supply them.

Do indoor cats need a vitamin D supplement?

Not usually. A complete and balanced food contains all the nutrients a cat requires, vitamin D included. AAFCO notes that supplementing on top of it risks exceeding the upper limits of certain nutrients.

Can I give my cat human vitamins?

No. Merck notes that some human vitamins contain ingredients toxic to animals, including xylitol. Keep them where your cat can't reach them.

Which nutrients matter most for cats?

All of them, in balance. Cats do have unusual needs: ready-made vitamin A, niacin from food, and taurine for cats, an amino acid the ASPCA says is found only in foods of animal origin.

Are cat supplements checked by the FDA before sale?

Not as a rule. The FDA regulates them as food or as animal drugs by intended use, and animal food doesn't need FDA review before it is sold.

Sources

• Cornell Feline Health Center: Feeding Your Cat
• ASPCA: Cat Nutrition Tips
• WSAVA Global Nutrition Committee: Frequently Asked Questions and Myths
• Merck Veterinary Manual: Nutritional Requirements of Small Animals
• Merck Veterinary Manual: Proper Nutrition for Cats
• Merck Veterinary Manual: Kitten Care
• Merck Veterinary Manual: Bone Disorders in Cats
• Merck Veterinary Manual: Toxicoses in Animals From Human Multivitamins and Supplements
• AAFCO: Supplements
• AAFCO: Selecting the Right Pet Food
• FDA Center for Veterinary Medicine: “Complete and Balanced” Pet Food
• FDA Center for Veterinary Medicine: FDA’s Regulation of Pet Food

This article is for general information and is not veterinary advice. Talk to your vet about your own cat — they know the animal in front of them.