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It is not raining vitamin D
No, the sun doesn’t have vitamin D. Vitamin D doesn’t fall from the sky. Vitamin D is made by your body, specifically by your skin. Then, why do we say the sun has vitamin D? Well, because we are a little confused about the topic. The starting point is that the sun is essential for us to make vitamin D. How so? It turns out that the same ultraviolet radiation that burns your skin if you spend too much time in the sun does something very interesting to the inside of your skin. But first, something else: you know what cholesterol is, right? It is a real pain for a few of us. Well, it turns out our body produces cholesterol because we use it for a lot of essential things. Now let’s join the dots.
The molecule that precedes cholesterol in its production process (the second-to-last before becoming cholesterol), when it receives ultraviolet rays from the sun, undergoes a change in its structure that turns it into “pre-vitamin D.” It’s like you’re a car traveling on the highway, heading for the “cholesterol” city, but a ray of sunlight hits you, causing you to take the next exit and end up in the “vitamin D” city. So, if you get sun, your skin converts a little bit of “pre-cholesterol” into “pre-vitamin D.”
Now, if you don’t get sun, then you don’t have vitamin D? The good thing we have, like most mammals, is that we can get vitamin D from what we eat. The vitamin D we produce in our bodies is stored in our liver. Therefore, if you eat a pig’s or cow’s liver, your digestive system rubs its hands together when it sees vitamin D passing by and absorbs it. Then, why doesn’t your cat care?
Cats (and dogs) can’t produce vitamin D
Well, your cat doesn’t care about the sun part, because cats can’t produce vitamin D. And neither can dogs. So, what do cats (and dogs) do to keep their bones healthy? Well, they get all their vitamin D from what they eat; they have no choice. And if it’s already strange that cats and dogs can’t make vitamin D no matter how much they lie in the sun, there’s another curious thing here. It turns out there’s vitamin D from animal sources and vitamin D from fungal sources (mushrooms), being their molecular forms slightly different. We humans can use both types of vitamin D, although the version produced by mushrooms takes a little more work for us to use. But cats, being felines, aren’t used to eating mushrooms. Cats can only get vitamin D from eating animals or fish. And dogs? For thousands of years, canines have been eating whatever they could find, and those that were able to harness the vitamin D produced by fungi and mushrooms made their way through the course of evolution.
Therefore, get some sun (in moderation) and with protection to give your body energy to make vitamin D. And give your cat animal-based foods.
