I am a big fan of the weather channel, mainly because I am Canadian. Our national pastime has always been to commiserate about how much the weather bites. Yet the one thing that detracts from my enjoyment of all weather related trivia is the incessant platitudinous warnings that admonish me to stay out of the “killer” sun. If perchance I do decide to indulge in a few rays, I am always told to wear sun screen and sun glasses so as to minimize the chances of contracting skin cancer, or exposing my eyes to full spectrum light, and the inevitable cataracts that will surely develop. One thing that all of the so-called authorities fail to mention however, is that since people started using sun screens, there have been no decreases in skin cancer rates of those who use sun screen compared to those who don’t. In addition, sun screens block out most UVB radiation (the necessary type that stimulates the production of vitamin D), while offering questionable protection from UVA (the type that can cause skin cancer). And to top it all off, no sun creams have to pass through FDA approval.
Although some of the effects of vitamin D, such as lowering MS rates, lowering cognitive impairments from Alzheimer’s and Parkinson’s diseases and cancer prevention are more commonly known, some eye diseases such as myopia, keratoconus, cataracts, optic nerve atrophy, retinitis pigmentosa and allergic conjunctivitis also respond favorably to vitamin D. These eye diseases were studied extensively by Dr. Alexander Knapp in the late 1930s as related to vitamin D levels, and were found to respond favorably to vitamin D and calcium supplementation.
Some additional effects that sun exposure causes are:
Increased testosterone secretion
Increased storage of glycogen by the liver and muscle
Lowering of cholesterol and triglycerides
So now you are probably asking “at what dose?” Well for starters, the RDA of 400IU/day is simply ridiculous. The minimum erythemal dose of 30 minutes of full body exposure to the sun will give you about 10,000IU in summer. For those who are sensitive to the sun and wish to stay out of it, 4000IU/day as a supplement is good. For those of you who worry about all of the hype about vitamin D toxicity, it would actually take 40,000IU/day for several years before you would become toxic. Even then, discontinuing that dose would allow you to recover uneventfully. However, I am not advocating sun-burning. If you want to avoid burning, simply wear a wide brimmed hat, long sleeves and pants and sun-glasses after you get your dose. As to the question of sunscreen, simply ask yourself “would I eat it?” If the answer is yes, then wear some (remember that the skin is a permeable barrier that will absorb what you put on it). If you are still doubtful of the above, this site will give you the full exposure if you will pardon the pun (http://www.vitamindcouncil.org).
Sunlight Could Save Your Life by Zane Kime, M.D.