Vitamin D is produced in the skin when it is exposed to UVB rays in a process that begins with the conversion of a precursor of cholesterol. Without going into the actual biological processes here, you could just think of it as photosynthesis of the skin. We do store Vitamin D in our fat cells and it is released in the winter months, given we allow our bodies to produce such quantities. The sunshine vitamin is present in different parts of the body and in various forms. Calcitriol is the form of active Vitamin D that circulates throughout the body and is in charge of regulating the metabolism of calcium. See, for most people the problem isn't not getting enough calcium, the problem is that they don't have enough Vitamin D to use the calcium they get and their acidic diet leaches a lot of calcium out of their bodies.
What has been more recently discovered is that there are Vitamin D receptors in every part of our body and this Vitamin, which also acts as a hormone, is involved in a whole lot more than just dealing with calcium. Dr. Micheal Holick, author of The Vitamin D Solution writes "If you had to choose a single nutrient that would help you ward off disease, cancer, diabetes, obesity, demintia, influenza, bacterial infection, depression, insomnia, muscle weakness, fibromyalgia, osteomalacia, osteoarthritis, rheumatoid arthritis, osteoporosis, psoriasis, multiple sclerosis, and hypertension, it would be vitamin D" !
Pretty impressive I think! More on that tomorrow, and also we'll talk about how much to take in supplement form.