STANFORD, Calif. Light-skinned people who avoid the sun are twice as likely to suffer from vitamin D deficiency as those who do not, according to a study of nearly 6,000 people by researchers at the Stanford University School of Medicine. Surprisingly, the use of sunscreen did not significantly affect blood levels of vitamin D, perhaps because users were applying too little or too infrequently, the researchers speculate.
The study adds to a growing debate about how to balance the dangers of sun exposure with the need for appropriate levels of vitamin D to prevent bone diseases such as osteoporosis and rickets.
"It's not as simple as telling everyone to wear sunscreen," said dermatologist Eleni Linos, MD PhD. "We may instead need to begin tailoring our recommendations to the skin tones and lifestyles of individual patients. It's clearly a very complex issue."
Linos, who is now an assistant professor of dermatology at the University of California-San Francisco, was a Stanford resident when the research was conducted. She is the first author of the research, which will be published online Nov. 4 in Cancer Causes and Control. Assistant professor of dermatology Jean Tang, MD, PhD, is the senior author.
Vitamin D is produced by the skin in response to exposure to the ultraviolet rays in sunlight; too little of the vitamin causes bone weakening and rickets and possibly contributes to many other chronic diseases including cancer. Small amounts of vitamin D can also be acquired by drinking fortified milk, eating fortified breakfast cereals or eating fatty fish such as salmon, tuna and mackerel, as well as from over-the-counter dietary supplements. Although it's not clear exactly how many people may be deficient in the vitamin, experts believe about 30 to 40 percent of the United States population may be affected.
Linos and Tang analyzed population-base data from the U.S. National Health and Nutrition Examination S
|Contact: Krista Conger|
Stanford University Medical Center