The American Cancer Society, or ACS, estimates 2 million Americans will be diagnosed with skin cancer this year, and one in five people will develop skin cancer in their lifetime. Given such incidence rates, the ACS recommends the use of sunscreen with a sun protection factor of at least 15. However, vitamin D, often called the sunshine vitamin, has garnered interest in recent years for the role it may play in cancer prevention.
Effects
A tan is the result of your skin being exposed to ultraviolet rays. Sunlight has two kinds of ultraviolet rays, UVA and UVB. The rays penetrate the epidermis, or outer layer, of your skin, causing the body to produce more melanin, a pigment responsible for the color of your skin. Exposure to these rays, especially UVA, can suppress your immune system and lead to the development of skin cancer. The United States Department of Health and Human Services listed ultraviolet rays from the sun and tanning beds as a known carcinogen, or cancer-causing substance, in its latest report. Interestingly enough, many people tan for aesthetic reasons, to look and feel better, which the American Academy of Dermatology called "ultimately self-defeating," as chronic exposure to the sun causes wrinkling and age spots.
Benefits
One of the benefits of tanning is that exposure to the sun prompts the body to produce more vitamin D. Even after a relatively short time in the sun, as little as 15 minutes, the body can make vitamin D for hours afterward. And while vitamin D has been long linked to bone health, some studies have suggested it may play a role in cancer prevention. After reviewing several of these studies, the National Cancer Institute concluded that while there is some evidence showing vitamin D may reduce your risk of colorectal and some other cancers, "the evidence of potential benefit is limited and inconsistent."
History
Sunscreens have been commonly used since the 1950s, with the sun protection factor, or SPF, first introduced in 1962. The SPF measures the effectiveness of sunscreen. A sunscreen with an SPF of 20 means you can be exposed to ultraviolet rays for 20 times longer than the time it would normally take your skin to burn. Sunscreens come in gels, lotions and creams and are now water, heat and sweat resistant.
Considerations
The use of sunscreen is not without controversy. There are 17 ingredients approved by the Food and Drug Administration for use in sunscreen. Sunscreens contain chemical ingredients such as zinc oxide and titanium dioxide that absorb or reflect ultraviolet rays, ultimately blocking them from penetrating the skin. These ingredients are reduced to nanoparticle form when used in sunscreen, and there has been some concern they can potentially damage healthy cells if absorbed into the skin. A February 2006 study conducted by the Australian Department of Health and Aging Therapeutic Goods Administration, concluded that the majority of evidence shows titanium dioxide and zinc oxide are not absorbed into the body and remain on the outer layer of the skin, negating any harmful side effects.
Recommendations
Despite the benefits of vitamin D and concerns about chemical ingredients, the overwhelming consensus in the medical community is that sunscreen is necessary for the prevention of skin cancer. The American Academy of Dermatology recommends applying sunscreen at least 15 minutes before you go out in the sun, paying close attention to your face, ears and arms. Sunscreens should be reapplied every two hours or after swimming. If you have any concerns about adequate vitamin D intake, you should consult your doctor.
