(Credit: vvvita/Shutterstock) My doctor recently declared me deficient in vitamin D and prescribed a weekly pill. Because I take care to eat a healthy and diverse diet, I was a bit annoyed. She said it was no big deal and actually very common, the medical equivalent of a parent telling a child, “Because I said so.” Later on, I was grousing to some of my friends and many of them said they had gotten the same news. It made me wonder: What is going on with vitamin D?
Truth be told, we shouldn’t really need vitamin D in our diets at all. Humans and other animals can synthesize this molecule right from cholesterol, something we always have plenty of. Doing so, however, involves a rather obnoxious biochemical pathway. The synthesis of vitamin D begins in the skin with activation of a precursor molecule by ultraviolet light from the sun. After ...
