Did you know the sun produces 3 types of ultraviolet (UV) Rays? There are UVA, UVB, and UVC rays. The atmosphere completely absorbs the UVC rays. However, both the UVA and UVB rays reach our bodies…but they have a different effect on us.
UVA rays are known to cause wrinkles and at high doses may be the cause of skin cancer-melanoma. UVA radiation does not have the ability to enable us to produce vitamin D. UVB radiation, however, is responsible for sunburns and vitamin D production. Since, UVB radiation can cause sunburns if in the sun too long-UVB radiation may also be part of the cause of skin cancer-melanoma. This is due to the fact that when we develop a sunburn we cause mutation to the skin cells. These skin cells replicate in a mutated state until later they appear in the form of skin cancer. Thus, the key is not to burn.
Sunscreens were first used in the 1940s. What I have found most interesting is up until the late 1990s these sunscreens only blocked UVB radiation (the UV rays that cause sunburns). These sunscreens did not protect against UVA radiation; as they were not thought to be harmful rays, since they did not cause sunburns. Thus, allowing us to absorb mega doses of UVA radiation that we would not normally be able to stay out in the sun and absorb.
Perhaps, this gives us some insight as to why melanoma rates have been increasing by 2% every year over the past thirty years. We now know, UVA radiation at high doses is thought to be one of the causes of skin cancer- melanoma. Therefore, UVB protection only sunscreens have been phased out and broad spectrum sunscreens were developed. This occurred in the late 1990s. These broad-spectrum sunscreens protect us against both UVB and UVA radiation.
Dr. Holick, our nation’s leading expert on vitamin D, completed studies involving sunscreens. His data demonstrates: sunscreens with a SPF 8, reduces vitamin D production by 97.5% and SPF 15, reduces it by 99.9%. Therefore, sunscreens almost completely prevent the body from making any vitamin D from the sun. The point to remember is that it is okay to get “raw” exposure to the sun- 10-15 minutes 2-3 times per week. The key is not to burn. After about 10-15 minutes of “raw” exposure to the sun you should utilize a broad-spectrum sunscreen to protect against having a sunburn.
Lastly, I often get asked, “Can I get a sunburn or UVB radiation from sunshine that warms the skin through a window?” No. UVB radiation from sunlight does not penetrate through glass. Thus, you will not burn and your body will not make vitamin D from sunshine through a window.
So go out in the sun responsibly. Do not burn. Use broad-spectrum sunscreens if you plan to be out in the sun longer than 10-15 minutes to prevent sunburn. Use common sense. Sunshine is not to be feared. Sunlight is the fuel that enables us to manufacture vitamin D. The benefits of vitamin D on human health are many, varied and profound. Just as with oxygen, air, water, our bodies need sunshine. Use it responsibly.