Research shows skin color is gateway for sunlight, vitamin D – Washington Times
“You’ve got people from England moving to Australia; people from West Africa moving to Finland. You have this dramatic movement of people to environments to which they are poorly adapted from a solar perspective.”
Another modern development, urbanization, means people are spending more and more time indoors.
From a health perspective, these trends have had a bigger effect on darker-skinned people, she said. Lighter-skinned people can adapt to sunny climates by using sunscreen to prevent skin cancer and folate problems and yet still get enough of the ultraviolet B radiation that triggers vitamin D production.
“If you’re a darkly pigmented person living in a far northern place or living in a city and not getting much sun exposure, though, then we are not addressing the problem of likely vitamin D deficiency,” Ms. Jablonski said.
Lisa Bodnar, a researcher at the University of Pittsburgh’s Graduate School of Public Health, has found this trend in her studies of pregnant women.
Ms. Bodnar, who has a doctorate in nutrition, has found that women who have vitamin D deficiencies are more likely to deliver babies early or get the dangerous condition of preeclampsia, which causes a woman’s blood pressure to spike and often leads to premature delivery of her child.
Even using the most conservative guidelines of how much vitamin D women should have, Ms. Bodnar said, nearly half of African-American mothers have vitamin D deficiencies, compared with just 10 percent of Caucasian mothers.
Adding to this picture is a study Ms. Jablonski and colleagues in South Africa have been conducting among residents of Cape Town.
Among darker-skinned South Africans, she said, the more time they spend indoors, the lower their vitamin D levels, and the weaker their immune systems.