Low Vitamin D May be a Deadly Problem for Cats

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Vitamin D is just one more way your cat’s food may be killing her.

Recently Rachael Ray Nourish wet cat food was recalled over elevated Vitamin D levels. This coincided with a conversation I just had with a veterinary nutritionist about study regarding Vitamin D in cats.

A study published May 13, 2015 found that the level of Vitamin D in the blood of hospitalized cats predicted their likelihood to survive. In fact, in this case it was low Vitamin D levels that indicated a higher risk of death in these sick cats.

Food is the only source for Vitamin D in cats. They do not manufacture it in their skin with the help of sunlight like people do. This led me to ask the nutritionist about Vitamin D levels in cat food. Could low levels in cat food be responsible for poor disease recovery? Might it be causing fatal disease in the first place?

The study did not answer these questions, it simply noted the correlation. Low Vitamin D levels could just be a marker of some other unknown factor. And the food may not be the culprit. Maybe some cats can’t absorb or metabolize Vitamin D properly. Maybe it’s the absorption or metabolism problems that led to the poor recovery of these cats.

A previous study found that cats with tooth resorption (a painful disease of cats that causes their teeth to dissolve at the gum line) have significantly higher serum concentrations of Vitamin D than do cats without this condition. In a separate study, these researchers also found that 41% of canned cat foods have in excess of 30 times the vitamin D requirement of cats.

Vitamin D is an extremely important vitamin. It acts as a hormone in the body and regulates calcium metabolism which is important in bone growth and maintenance. Vitamin D deficiency causes Rickets in the young and osteomalacia (softening of the bones) in adults. Vitamin D excess leads to too much calcium in the blood. This can cause calcification of body tissues and the formation of bladder stones. Either too much or too little Vitamin D in cat food is a serious problem.

It is truly the Wild West when it comes to Vitamin D for cats. The nutritionist I spoke to told me of her research into the Vitamin D contents of cat foods. She found that the Vitamin D in feline diets ranges from 98 – 1,305 IU/1,000 Kcal. The AAFCO guidelines allow for levels of 125 – 2,500 IU/1,000 Kcal.

Why such a wide range? Well for one thing, other components of the food affect Vitamin D metabolism. For example, dietary fiber decreases Vitamin D absorption. So you would expect a weight-loss diet that uses fiber to decrease calories to require a higher Vitamin D level.

But most of all, I think pet food companies are clueless about the appropriate level of Vitamin D for their foods. My suggestion; grind up a mouse, measure the nutrient levels, and mimic those. Mother Nature still knows best! I’ll let you know if anyone ever follows my advice (don’t hold your breath).

I suggest sticking with a cat food that is as close to the cat’s natural diet as possible (raw that is balanced using food-source nutrients not synthetic vitamins).

Do you trust your cat’s food? Why or why not?

6 replies
  1. brit
    brit says:

    wondering how dog/cat species obtain their D in the wild, is it from liver? Also how much should I give my raw fed 50lb dog. He gets chicken/duck or turkey necks for breakfast and meat chunks (usually beef heart) for dinner with crushed raw veggies, rotated with a frozen raw mix that contains some liver a couple of times a week. thanks brit

    • Dr. Doug
      Dr. Doug says:

      It makes sense that liver would be the major source of vitamin D for wild carnivores. I do not have the computer programs needed to answer your question about how much to feed. I would suggest Dr. Karen Becker’s diet book.

  2. Alex
    Alex says:

    Your statement “I think pet food companies are clueless about the appropriate level of Vitamin D for their foods. My suggestion; grind up a mouse, measure the nutrient levels, and mimic those. ” tells me that you are cluless about where cats get Vitamin D from. My cat laying next to the window will not get her Vitamin D from sun because she is behind window glass. Not because she has fur covering her skin. If she exposed to enough UVB her fur is covered with a thin layer of cholesterol from sweat/sebaceous glands that is converted to Vitamin D3 during that sun exposure . Cats get a boost of vitamin D after grooming that radiated fur after sleeping under open sun. Vitamin D3 you pick up at Walgreens comes from cholesterol of sweat/sebaceous glands of sheep, exposed to artificial sunlight. We don’t leak sheep, but cats do groom themselves on sunny day in natural environment. Just FYI.

    • Dr. Doug
      Dr. Doug says:

      Hi Alex – Thanks for reading the post. From the research that I’ve seen cats get all their Vitamin D from their food. Here’s a study to check out. http://jn.nutrition.org/content/129/4/903.short It takes more than sunlight and cholesterol to make vitamin D. It also requires the participation of enzymes in the skin which apparently are not very active in cats.

  3. Sue E. Williams
    Sue E. Williams says:

    I have a 5 year old rag doll cat that had parasites which we were not told. Her companion rag doll had giardia and had lived one week away from the cattery then given to us he also had another parasite and by the time the vet found it he got free of the parasite but died at 9months. But the rag doll that is alive was left with IBD. She is on prednisone and has been low in vitamin D3. The Dr. has increased her Vitamin D3 and he’s a good vet. He told me she has a severe IBD. He is out of town for a few days. He updated today vitamin D3 to 11 drops a day. Is it safe to go through that change all in one day or work up to 11 in increments.


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