Although the risks of sun exposure have been greatly overblown, anyone who has ever gotten a sunburn knows that too much sun genuinely can damage your skin. What is less well known is that for many years, sunscreens only protected you from the potentially beneficial, vitamin D producing UVB rays, while letting through skin-damaging UVA light.
Both UVA and UVB can cause both tanning and burning, although UVB does so far more rapidly. UVA, however, penetrates the skin more deeply than UVB, and may be a much more important factor in photoaging, wrinkles and skin cancers.
Even today, while most sunscreens do a good job blocking UVB, fewer filter out all of the UVA. That means they do not help to prevent the beginnings of melanoma formation. In fact, a sunscreen without adequate UVA protection can end up increasing your risks. If you think you are protected by sunscreen, you are likely to stay out in the sun longer -- and all the while, you will be soaking up the highly penetrating, wrinkle and cancer causing UVA radiation without the warning sign of a burn (remember that a UVA burn takes much longer to appear).
I’m not a big fan of sunscreen use on a regular basis; even when it works, it blocks your body’s natural production of vitamin D. But in situations where you must be out in the sun long enough to burn, be sure to use a product that protects against both UVA and UVB, such as Natural Sunscreen, which uses a titanium dioxide/zinc combination that reflects both types of rays -- while also giving you a beautiful, glowing and healthy tan.
* Journal of the American Academy of Dermatology May 2008, 58 (5 Suppl 2): S160-6
* Medical College of Wisconsin Healthlink