What is Vitamin D and how much do you need?
Although called a vitamin, it is not. Vitamin D is in a class by itself, behaving more like a hormone. It is made in the skin, gets into your bloodstream and then goes into the liver and the kidney where it becomes activated as a key steroid hormone called Calcitriol. It then goes to the intestines, bones and other tissues, effecting metabolic pathways and the expression of myriad genes.
Vitamin D’s active form can interact with almost every cell in the body directly or indirectly, targeting up to two thousand genes, or about six percent of the human genome. It is necessary for numerous cellular functions, and when the body does not have what it needs to function optimally, it follows that we experience a decline in health and put ourselves at risk of disease. We now know that almost every cell and tissue in our body has vitamin D receptors, which raises the question: Why would those receptors be there if they weren’t meant to have an effect?
Our vitamin D needs vary with age, body weight, percent of body fat, latitude, skin coloration, season of the year, use of sun block, individual reactions to sun exposure, and our overall health. As a general rule, older people need more vitamin D than younger people, large people need more that small people, fat people need more than skinny people, northern people need more than southern people, dark-skinned people need more than fair skinned people, winter people need more than summer people, sun-phobes need more than sun worshipers, and ill people may need more than well people.
The best way to determine whether or not you are deficient is to have your vitamin D blood levels measured and replenish accordingly.