Fun in the Sun: Vitamin D

What better time to talk about Vitamin D than from the beach! We've all heard it before "wear your sunscreen" and "tanning is bad" or "not too much sun exposure, you'll get skin cancer!" Are these exclamations accurate though? Does sunscreen really help me and prevent cancer? Today we'll look at this vital vitamin and see what truely needs to be done! I've been doing a lot of reading lately and it seems that all of the books have a similarity, in that they all talk about Vitamin D (The Paleo Diet, Hormonal Enhancement, and Primal Blueprint all talked about it), so let's get down to business and see what's really going on.
So what does vitamin D do? Sunlight provides 7-dehyrocholesterol to the skin, which then manufactures vitamin D. It then regulates calcium levels and phosphate in the bloodstream and promotes mineralization and growth of bones (with assistance from calcium, Vitamin A, and Vitamin K2 of course). It plays a major role in immune response, by activating T-cells for defense against infections and bacteria. Moderate sunlight (according to a Stanford University study) allows immune cells in the skin to activate vitamin D3, so that these T-cells can transfer to the outer layers of the skin. Not only is it important for bone density and the immune system, but it helps the heart pump better, lowers blood pressure, decreases inflammation, and helps reduce insulin resistance. Also of note is it's importance for healthy teeth and nails, eyesight, nutrient absorption (calcium and vitamins A and C), and prevention of diabetes and autoimmune diseases.
What about cancer though, aren't I going to get skin cancer from sun exposure? Actually sun exposure is protective of cancer! It helps prevent: lung, kidney, breast, endometrial, ovarian, prostate, colon, and skin cancers. Vitamin D prevents cancerous cells from dividing and it quickens the death of cancer cells! Most think that since the use of sunscreen, that skin cancer rates have decreased. This is false, skin cancer rates have actually gone up! Sunscreen block UVB rays and allow UVA rays in. This provides a false since of security, because the skin doesn't pinken, people often are overexposed to the sun (moderate sun is good, but overexposure and burns are troublesome).
Recommendations? I realize that sun exposure (especially here in the Midwest during the winter) is difficult sometimes. I would recommend getting adequate sunlight whenever it's possible. It's easy, free, and most of all fun. Just remember that you want to prevent overexposure (especially fair-skinned individuals). Ease into it, maybe 15 minutes a day. Remember that a tan is protective, but pinkiness is a warning, so if it's summer and you're going to be out longer, look for sunscreens that protect against UVA and UVB rays, or best of all cover up (white clothing is best). Darker skinned individuals need more sun exposure than fair-skinned, because it takes more sunlight for them to be able to absorb the proper amount of vitamin D. What about when it's winter, or I can't get outside. Supplement; 4000 IU is a good starting point, maybe have your levels checked before you begin any kind of supplimentation. A side note, though, to further back-up my belief in a grain-free, starchless, sugarless existence; grains actually decrease calcium absorption, so you need even more vitamin D. In closing get out and enjoy the sun when you can (in moderation) and when you can't then supplement; but now it's summer and a perfect time to be out with your family and maybe even play (see Sunday's article)!