WebMD Medical News
Laura J. Martin, MD
Oct. 5, 2011 -- Pale people and the sun just don’t mix.
People with pale skin tend to be more prone to sunburns -- and skin cancer. So, they often take steps to avoid the sun and slather on sunscreen when they are exposed to the sun’s rays.
As a result, they may make less vitamin D and may benefit from vitamin D supplements, according to a new study in Cancer Causes and Control.
Our bodies make vitamin D, also known as the sunshine vitamin, when we are exposed to sunlight. Vitamin D had become a rock star among vitamins in recent years as deficiency has been linked to brittle bones, heart disease, diabetes, cancer, and certain autoimmune diseases.
Sunlight -- 10 to 15 minutes a day -- is a good source of vitamin D, but it can also be found in foods such as fortified milk, butter, eggs, fatty fish, and supplements. Other factors such as our genes can influence the level of vitamin D in our bodies.
In the study, researchers defined optimal blood levels of vitamin D as 60 nanomoles per liter (nmol/L). Of 1,200 people. some with the skin cancer melanoma and some without melanoma, 730 had low levels of vitamin D. Some were the melanoma patients. Based on previous research, people with melanoma may have low levels of vitamin D and need supplements, the researchers suggest.
Also, participants with a specific genetic variant involving vitamin D were more likely to have low vitamin D levels, the researchers found.
But it was the pale-skinned people in the study who were among the most likely to show low vitamin D levels. “Fair-skinned individuals who burn in the sun tended to have lower levels of vitamin D,” researcher Julia Newton-Bishop, MD, says in an email. She is a professor of dermatology at the University of Leeds, U.K. "Our data suggested that this was because they spent less time in the sun but probably was also related to covering up more."
So just how much vitamin D supplementation should pale-skinned people take?
That is a difficult question to answer, Newton-Bishop says.
An Institute of Medicine (IOM) panel recently reviewed a wealth of research on vitamin D and raised the recommended daily intake to 600 international units (IU) for everyone aged 1-70 and to 800 IU for adults older than 70.
"I generally suggest that people should follow their national recommended daily allowance but adjust using common sense," Newton-Bishop says. "If someone has a passion for wild salmon then as this is a good source of vitamin D, they might not need supplements every day."
This is important, she says, because there can be too much of a good thing.
"I am concerned about very high doses generally, being concerned that high blood levels might be as bad as insufficiency," Newton-Bishop tells WebMD. "On the Net, one can buy preparations containing 10,000 IU for example, and I would certainly not see this as in any way sensible."
Michael F. Holick, MD, PhD, director of the vitamin D skin and bone research lab at Boston University, says that vitamin D supplementation may be even more important for people who are pale.
Holick says that we all need more vitamin D than the IOM calls for. "Take a supplement, and if you want sensible sun exposure that is fine too," he says.
Vitamin D expert Bruce W. Hollis, PhD, of the Medical College of South Carolina in Charleston, also urges people to take more vitamin D. He recommends guidelines released by the Endocrine Society that state that:
"These are the guidelines we should follow," Hollis says. "These guidelines may be even more important in people with pale skin who habitually avoid any unprotected sun exposure."
SOURCES:Michael F. Holick, MD, PhD, director, vitamin D skin and bone research lab, Boston University.Bruce W. Hollis, PhD, Medical College of South Carolina, Charleston.Davies, J.R. Cancer Causes Control, 2011.
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