Sorting out the Sun
The threat of skin cancer has terrified us. Vitamin D deficiency has plagued us. We know that too much sun isn't good for us, but we are hearing more and more the importance of sun exposure. Hopefully this article will end the confusion, so you can stock up on the benefits of the sun this summer.
Why Do We Need Vitamin D?
Vitamin D is a fat soluble vitamin that is stored in fatty tissues of our body. Its main function is in mineral metabolism and bone growth. We need to have adequate Vitamin D to prevent osteoporosis, osteomalacia, and rickets as well as tetany, which is painful muscle spasms due to low calcium levels.
Other functions include including modulation of cell growth, neuromuscular and immune function and reduction of inflammation. Vitamin D also plays a strong role in the prevention of colon, prostate, and breast cancers. In addition, it protects against depression particularly in sufferers of SAD, insomnia, and some autoimmune diseases like psoriasis.
Lastly, we need Vitamin D for a properly functioning reproductive system and Vitamin D levels greater than 50 may be required for optimal fertility.
Where Do We get Vitamin D
We can get Vitamin D from supplements and certain foods like cod liver oil, eggs, and fortified dairy products. It is also produced in our bodies when ultraviolet rays from the sun hit our skin triggering 7-dehydrocholesterol to be converted to previtamin D (precalciferol). After 2-3 days, precalciferol enters the blood stream as cholecalciferol (Vitamin D3, calciol). Then it is converted in the liver to 25- hydroxyvitamin D [25(OH)D] (calcidiol). Finally it will become the active form 1,25- hydroxyvitamin D [25(OH)D] (calcitriol) in the kidneys. Unlike from supplements, we cannot overdose from the Vitamin D we get from the sun, because the sustained heat on the skin is thought to photodegrade previtamin D3.
How to Get the Most Out of the Sun
Except during the summer months, the skin makes little if any vitamin D from the sun at latitudes above 37 degrees north or below 37 degrees south of the equator. That's north of San Francisco on the West coast and Richmond, VA on the East coast. People who live in these areas are at relatively greater risk for vitamin D deficiency and need to take advantage during the summer.
In the summer, about 15 minutes of exposure on the hands, face, and forearms three times a week between 10am and 3pm should provide adequate vitamin D and allow for storage of any excess in fat for use during the winter with minimal risk of skin damage. A sunscreen may be applied after the 15 minutes, if additional sun exposure is planned.
Barriers to the Sun
If you spend all your time out in the sun with sunscreen then you will certainly not be getting enough as a sunscreen with an SPF factor of 8 reduces production of vitamin D by 95%. Also complete cloud cover reduces UV energy by 50%; shade (including that produced by severe pollution) reduces it by 60%. You must be outside as UVB radiation does not penetrate glass.