Are Cats Absorbing Vitamin D When Lying in the Sun?

While she may love taking in the sun, she is not making vitamin D like you are.
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While your doctor may have told you to spend a little time in the sun for your body to create vitamin D, a cat’s body works a little differently. While she sprawls out in that ray of sunlight coming in the window, creating vitamin D is not the reason.

Vitamin D and You

Vitamin D is a vitamin that promotes calcium absorption and is essential for bone growth. It also helps cells grow, keeps your immune system functioning and reduces inflammation. You can get vitamin D three ways – exposure to ultraviolet rays from the sun, specific foods in your diet and dietary supplements. When you expose your skin to sunlight, it creates vitamin D through synthesis. Vitamin D is not found naturally in a lot of food sources, so for you, sun exposure or supplementation is often necessary. Food sources of vitamin D include fatty fish, such as salmon, egg yolks, cheese and other dairy products fortified with vitamin D.

Vitamin D and Your Feline Friend

Your cat, on the other hand, does not process vitamin D in the same manner. Because of her beautiful coat of fur, her skin and body are not designed to synthesize vitamin D. A 1999 study published in “The American Society for Nutritional Sciences” looked at vitamin D and sunlight exposure in kittens. During the study, the kittens ate a vitamin D-free diet and exposed to either direct sunlight, ultraviolet lamps or kept indoors. All three sets showed similar declines in vitamin D levels. The kittens in the sun and ultraviolet lamp groups then had a section of their fur removed to see if the coat reduced vitamin D synthesis. There was no change, showing that cats simply do not synthesize vitamin D in the same way. Their vitamin D comes from their diet.

Vitamin D and Your Cat’s Diet

Now that you know she is not lying in the sun to get her vitamin D, it is important to know where she is getting it. Her vitamin D is coming from the food you feed her. The U.S. Food and Drug Administration’s Animal and Veterinary Department recommends vitamin D levels in foods that vary based on a cat’s development age. If your furry friend is a kitten or pregnant female, she should receive 750.0 International Units per kilogram, or IU/kg. For adults, that number drops to 500.0 IU/kg. Both age levels have a maximum daily amount of 10,000.0 IU/kg.


Excessive amounts of vitamin D can be toxic to cats and leads to a condition called vitamin D toxicosis or poisoning. Making sure the food you feed her has vitamin D levels within the recommended levels is essential. Symptoms of vitamin D toxicosis include anorexia, vomiting, diarrhea, increased thirst and urination as well as depression. In addition to cat food, making sure she does not have access to your vitamin supplements is essential. Leaving out your morning vitamins on the counter could be tempting to your feline friend but very dangerous in the end. If you suspect she has ingested a vitamin D supplement, seek veterinary care immediately. Do not provide vitamin supplements to her unless your veterinarian prescribes them.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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