Oct. 5, 2011 -- Pale people and the sun just don’t mix.
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."
Too Much Vitamin D Not Such a Good Thing Either
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."