Last year the FDA approved new labeling for sunscreens that block UVA light. Finally we have a four star system to block UVA. We are all familiar with the sun protection factor (SPF) system. These products were designed to block UVB light. Thirty-five years ago and up until just recently it was believed that UVB was the most damaging spectrum of light and that by blocking it they could prevent sun damage to the skin and skin cancer.
In the last 25 years we have learned that UVB is the spectrum of light that is needed to make vitamin D. More recently we have learned that the ratio of UVB to UVA is important in determining the risk for skin cancer. The higher the ratio is, the lower your risk of skin cancer. The Nurses Health Study published results in March 2008 showing that squamous cell carcinoma of the skin is the principle sun related cancer. Basal cell carcinoma is only modestly sun related. AND, the kicker, melanoma did not relate to sun exposure over a lifetime.
This study confirms other studies in the last 5 years showing that you are less likely to get melanoma or die from it if you have a history of greater sun exposure or higher vitamin D levels. In essence, we have been blocking the wrong spectrum of UV light for the past 35 years. Too much UVA relative to UVB is probably the skin cancer culprit along with a history of sunburn as a child.
Sun screens will now have two rating systems 1-4 stars for UVA blocking ability and the SPF number. The more stars the more UVA blocking power. Sunscreens which do not block UVA are now required to have a label stating this. You should never buy an SPF only sunscreen. A sunscreen with SPF 8 applied appropriately blocks 97 percent of vitamin D production. A 3 star, SPF 8 sunscreen should provide more than adequate protection AFTER you have had enough sun to make vitamin D.
The Vitamin D Cure has tables that help you calculate the number of minutes of sun exposure to make vitamin D. The burn time is about 4 times the D-time. So if it takes you 15 minutes to make vitamin D according to the tables, it will take an hour to burn. So, you have a fairly large safety window before you need to apply your sunscreen.
You can also use the sun exposure tool at www.thevitamindcure.com to calculate your D-time. Research tells us that as an adult you are better off erring on the side of infrequent overexposure than chronic underexposure to sunlight. So go out there and get some healthy sun exposure!