Shedding light on sunscreen, vitamin D
By Maj. Ronea Harris-Stith, 779th Medical Operations Squadron dermatologist
/ Published May 21, 2009
ANDREWS AFB, Md. --
There is no better time to discuss sun safety than the present. With spring in full bloom and summer fast approaching, we have already begun to enjoy the warmth of the season.
Protecting skin from the harmful effects of overexposure to the sun is the ultimate goal, and that can be accomplished using a combination of approaches.
Avoidance of the sun during peak hours, between 10 a.m. and 4 p.m., is the first line of defense in skin protection. If unable to plan activities outside of peak hours, then seeking shaded structures and using protective clothing can help. Wearing broad-rimmed hats, sunglasses, and light weight, dark colored long sleeves can provide important barriers to ultraviolet penetration.
After avoidance and protective clothing, sunscreen is the third line of defense in sun protection. Sunscreen is designed to absorb or block ultraviolet light from penetrating the skin. It is usually in the form of a cream, gel, wax stick or spray. Sunscreen is often a key component in many facial moisturizers, aftershaves, and other products designed to even out skin tone. Many brands exist, but those containing ingredients which prevent absorption of the broadest amount of ultraviolet light perform best. The following list includes such ingredients:
avobenzone (Parsol 1789)
ecamsule (Mexoryl SX)
sulisobenzone titanium dioxide
Although these ingredients offer some protection, they are not absolute in how they perform. Application prior to sun exposure, amount of sunscreen used, reapplication time, and water/sweat exposure may all affect the efficiency. Therefore, applying thirty minutes prior to sun exposure, using an ounce, or "shot glass" amount, on exposed areas, reapplying after two hours and after water exposure, is recommended.
Concerns about the ingredients in sunscreen and the effects on vitamin D levels seem to be on the rise.
How does sunscreen use effect vitamin D levels? Since sun exposure is responsible for vitamin D production in the skin, wearing sunscreen can decrease the skin's production of the vitamin. Vitamin D cannot be used by the body until it is processed by the liver and kidneys. Therefore, vitamin D produced in the skin or absorbed from the diet is processed the same! Furthermore, many studies have suggested that the amount of vitamin D consumed through diet and supplements, and/or 15 minutes of exposure daily, is sufficient to keep levels in the normal range. Foods rich in vitamin D include fortified milk, cheeses, yogurt, cereal, salmon and tuna. Individuals who wear sunscreen and are concerned that they are not getting enough vitamin D, should discuss their options for obtaining sufficient vitamin D from foods and/or vitamin supplements with their doctor.
Overexposure to the sun can cause uneven skin tone, premature aging, and skin cancer. Skin cancer is curable if detected early. Taking steps now to avoid overexposure can help prevent skin cancer in the future. Sunscreen use is only one of many ways to help protect skin from the harmful effects of the sun. Avoidance during peak hours, protective clothing, and seeking shade are also effective methods. If you missed your opportunity to observe "Melanoma Monday" on May 4, then make up for it on today on "Don't Fry Day." Taking good care of your skin now will help you have many healthy, fun-filled summers in the future.