Sunlight is a source of energy for every kind of life on this planet. Cats are the most loveable and commonly kept companion animals because of their calming and stress lowering benefits. Cats are sun lover creatures and mostly love to take a nap in sunny spots to regulate their basal metabolic rate and maintain body temperature.

There are various breeds of cats that are easily adjustable to studio apartments, such as American Shorthair, Ragdoll, Russian blue, and many others, which feel comfortable in an indoor environment if you pay them sufficient attention.

Coming to the point, you usually hear that sunlight is a major player in the synthesis of vitamin D in your body. Ultraviolet rays of the sun stimulate the conversion of a chemical named 7-Dehydrocholestrol” that is present in the skin to an intermediate provitamin D, which finally transforms into an active vitamin D in the body.

Many cat keepers, especially those who have small apartments and keep indoor cat breeds, which frequently have little access to sunlight due to confined places, show concern about vitamin D related issues in their cats. They are curious to know whether cats need sun rays to produce vitamin D or not? Let’s mitigate this confusion with some logic and reasoning.


Cats of all ages require vitamin D, just like other animals, in an optimum proportion to stay healthy. Vitamin D has many key roles in cats; the following are the most important ones.

  1. This is necessary for bone and skeleton development.
  2. It has a major role in calcium and phosphorus metabolism.
  3. This vitamin aids in calcium absorption from the gut and kidneys.
  4. It has an overall impact on the reproduction, growth, and immune system of the body.
  5. Vitamin D also plays a main role in nerve and muscle control in cats.


Cats can also synthesize vitamin D with the help of sun exposure but not in that much sufficient amount, which they actually need for their well-being. There are a number of reasons behind this; cats don’t have enough amount of vitamin D precursor (7-hydrocholesterol) in their skin so, sunlight just mediates the conversion of little concentration of this precursor to active vitamin D.

A research study was conducted by K.L. How at the department of clinical sciences of companion animal, Urchet University, the Netherlands, to determine that if ultraviolet irradiation stimulates the production of vitamin D in cats or not. It was concluded that there was no significant increase in vitamin D3 in cats after exposure to ultraviolet rays; hence cats can’t produce adequate amounts of vitamin D3 due to less concentration of vitamin D precursor in their skin. So, they need adequate dietary supplements to meet their nutritional requirement.

James G. Moris in The Journal of Nutrition” The American Society of Nutrition published research that was based on the ineffective synthesis of vitamin D in kittens by sunlight. They made various groups of kittens; some were placed indoors, while others got sunlight and UV lamp exposure. It was also observed that, whether hairless kitten synthesizes vitamin after getting exposed to sunlight. But it was summarized that; there is not a strong association of sunlight with the production of vitamin D since there is a lower concentration of precursor in the cat’s skin.

Dr. Mauria O’ Brien at the University of Illinois Veterinary Teaching Hospital, Urbana, found that cats are unable to synthesize enough amount of vitamin D through sunlight, unlike humans. It was also emphasized that all mammal cells have vitamin D receptors. Cats require vitamin D to stay protected from bone and skeleton development troubles. So, it is mandatory that owners should feed cats with appropriate vitamin D fortified products in a recommended quantity.


Because of inadequate Vitamin D synthesis by sunlight, cats are dependent on other sources such as dietary supplementation that includes cat feed and some other natural diets enriched in vitamin D.



  1. Cat can’t produce a sufficient quantity of vitamin D through sunlight, so their feed should contain a balanced concentration of vitamin D along with calcium and phosphorous.
  2. According to the American Association of feed control (AAFC), cats require 750 IU (IU= International units), vitamin D3 per kg of diet on dry matter basis for growth, and reproduction. (This may vary with the type of breed and physical activities).
  3. Just like other animals, vitamin D has a major role in preventing rickets and other developmental complications in cats. Albeit, vitamin D is not required in high quantity by cats, but yet its importance can’t be ignored.
  4. The nutritional profile of commercially available cat feeds should be thoroughly checked for the quantity of vitamin D to ensure that whether your cat is taking a sufficient amount of vitamin D or not.
  5. It is noteworthy that a high level of vitamin D intake leads to toxicity (Hypervitaminosis) in cats that may be life-threatening to cats and worrisome for their owners. There must be proper care while supplementing cats with vitamin D, exclusively kittens since, and they are more prone to toxicity.


Crossley, V. J. et al. (2017) ‘Vitamin D toxicity of dietary origin in cats fed a natural complementary kitten food,’ Journal of Feline Medicine and Surgery Open Reports, 3(2), p. 205511691774361. DOI: 10.1177/2055116917743613.

How. K, L., Hazewinkel, H. A. W., & Mol, J. A. (1994). Dietary Vitamin D Dependence of Cat and Dog Due to Inadequate Cutaneous Synthesis of Vitamin D. General and Comparative Endocrinology, 96(1), 12-18. DOI:10.1006/gcen.1994.1154.

Morris, J. G. (1999) ‘Ineffective Vitamin D Synthesis in Cats Is Reversed by an Inhibitor of,’ (October 1998), pp. 903–908.

Crossley, V. J. et al. (2017) ‘Vitamin D toxicity of dietary origin in cats fed a natural complementary kitten food,’ Journal of Feline Medicine and Surgery Open Reports, 3(2), p. 205511691774361. DOI: 10.1177/2055116917743613.



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