Avoiding sun exposure may result in a vitamin D deficiency for light-skinned people, according to a study published by Stanford researchers on Thursday.
Interestingly, applying sunscreen did not affect test participants’ vitamin D levels, though researchers speculate this was a result of poor or sparse application.
Though sun exposure increases the risk of skin cancer, this study adds to the debate over how to best balance avoiding excess sun exposure and maintaining healthy amounts of vitamin D.
“It’s not as simple as telling everyone to wear sunscreen,” said dermatologist Eleni Linos, M.D. Ph.D. in a press release. “We may instead need to begin tailoring our recommendations to the skin tones and lifestyles of individual patients.”
Vitamin D production is triggered by the absorption of ultraviolet rays in sunlight, and a lack of the vitamin has been linked to weak bones, rickets and possibly cancer. Experts predict that 30 to 40 percent of people in the United States are vitamin D deficient, according to the University statement.
The research surveyed data from self-reported tendencies, such as how often a person enters the sun and how often they wear sunscreen. The study found that while sun exposure did not affect vitamin D levels in African-American or Hispanic respondents, Caucasians who received less sunlight had significantly lower vitamin D levels.
The study found that Caucasians who stayed in the shade and wore long sleeves were twice as likely to be vitamin D deficient as those who did not, causing Linos to emphasize the importance of vitamin D supplementation.
One interesting finding was that sunscreen use, which blocks UV rays and thus should decrease vitamin D production, had no effect on the users’ vitamin D levels.
“This finding was both interesting and surprising,” Linos said in the same press statement. “People are probably not applying it often or thickly enough.”
“Often, people use sunscreen when they anticipate getting a lot of sun exposure, unlike others who spend time in the shade in order to avoid the sun,” Linos said.
The study was funded by a Damon Runyon Clinical Investigator Award, the National Institutes of Health and the Department of Dermatology.
-Brendan O’Byrne