While scientists have known for decades that vitamin D deficiency leads
to bone diseases like rickets, more recently they have found
connections between low vitamin D levels and a wide range of other
illnesses, including cancer, autoimmune disorders and caradiovascular
The human body creates vitamin D through exposure
to sunlight, and yet some of the sunniest parts of the world have the
highest rates of vitamin D deficiency. Several factors have contributed
to dangerously low vitamin D blood levels among people in the Middle
East, Africa and Asia.
Vitamin D necessary for bone strength
Healthy bones depend on vitamin D, says Ambrish Mithal of the Indian Society for Bone and Mineral Research.
D is what absorbs calcium into our body and helps it reach the bone.
Vitamin D deficiency, therefore, results in weak bones and bones that
are soft, that will bend and break."
Getting enough vitamin D should be relatively simple.
major source of vitamin D is sunshine," Mithal says. "We make vitamin D
under the influence of UV rays that we get in the sunlight. We make it
in our skin."
Vitamin D deficiency common, even in sunny places
some of the world's sunniest regions have the highest rates of vitamin
D deficiency. That's the finding of a recent report from the
International Osteoporosis Foundation, which reviewed research done
over the past three decades. Mithal is a coauthor of that report.
D deficiency is a global phenomenon. But certain parts of the world,
they're prone to severe vitamin D deficiency - for example, South Asia,
like India, or Middle East, like Lebanon. There have been studies from
these areas which have shown that almost 80 percent, or maybe even
more, of the urban population is significantly vitamin D deficient."
He points to several factors to explain why people who live in sunny areas still may not get sufficient vitamin D.
who live closer to the equator are actually less prone to vitamin D
deficiency, but at times this, can be overshadowed by other factors
like skin pigmentation, less outdoor activity and more skin cover with
clothes," Mithal says.
Vitamin D expert Michael Holick, of the
Boston University Medical Center, explains why people with darker skin
generally have lower levels of the nutrient than lighter-skinned
people, even in the same country.
"The major reason is that
their melanin, which protects their skin from excessive exposure to
sunlight, also prevents them from making vitamin D," he says. "We
showed that African-Americans need to be exposed three to five times
longer to sunlight to be able to make the same amount as a white
Another coauthor of the vitamin D review, Ghada El-Hajj
Fuleihan, describes how people in the Middle East can spend time
outdoors without absorbing enough vitamin D.
"In these, the
Middle Eastern countries, people tend to follow a very much more
conservative clothing style, in a large proportion of subjects. And the
other thing is that with modernization, women who do not follow the
conservative clothing style use sunblock. Sunblock with sun protection
factor as low as six and eight can completely block the ability of the
skin to make vitamin D."
El-Hajj Fuleihan, of the American
University of Beirut Medical Center, says this may explain why women in
general have lower vitamin D levels.
Deficiency could be dangerous
is new concern about vitamin D deficiency because, as Michael Holick
explains, recent medical discoveries show it may be much more dangerous
than previously thought.
"What we haven't appreciated until
about the past decade is that vitamin D seems to be important for
reducing risk of many chronic illnesses that span anywhere from
autoimmune diseases like type 1 diabetes, multiple sclerosis,
rheumatoid arthritis, to infectious diseases like tuberculosis and
influenza, reduces risk of heart attack, stroke and most importantly,
reduces risk of deadly cancers."
Ways to get more vitamin D
can get more of the nutrient in their diet. In the United States and
other countries, some foods are fortified with vitamin D. But Holick
says that's generally not enough.
"Children probably need a
thousand units of vitamin D a day. Teenagers and adults need two
thousand units of vitamin D a day to satisfy their requirement… You
cannot get an adequate amount of vitamin D to satisfy your body's
requirement from your diet."
So, he and other experts like Ghada El-Hajj Fuleihan, now recommend spending a little more time in the sun.
are fully aware of the risk of skin cancer with sun exposure but
suggest that there may be a happy compromise and that maybe the first
10 minutes or so three times a week… let the skin get some ability to
make vitamin D, and then put the sunblock on."
In addition, she says, those who spend their days indoors should take a vitamin D supplement.
the World Health Organization has said that most people get enough
vitamin D through sun exposure and diet, in light of the new research,
it has commissioned its own report and may issue new recommendations.