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to Vitamin D main page : "Vitamin
D Might Cut Rist of MS, Study Says"
Top Stories - washingtonpost.com
Fri May 21, 1:00 AM ET Add Top
Stories - washingtonpost.com
By Rob Stein, Washington Post
Staff Writer
Many Americans, particularly
African Americans, may be suffering from unrecognized
deficiencies of a key nutrient -- vitamin D -- that
increase the risk of bone problems and perhaps a host
of other diseases, a growing number of scientists say.
Pediatricians scattered around
the country have been surprised to see children suffering
from rickets, a bone disorder caused by vitamin D deficiency
that had been largely relegated to a bygone era. A few
doctors have come across adults who were disabled by
severe muscle weakness and pain, sometimes for years,
until they were treated for undiagnosed vitamin D deficiency.
And recent studies suggest low vitamin D may be putting
the elderly at higher risk for the bone-thinning disease
osteoporosis and life-threatening falls and fractures.
But beyond bone and muscle problems,
some evidence suggests a dearth of vitamin D may be
associated with an array of more serious illnesses,
including many forms of cancer, high blood pressure,
depression, and immune-system disorders such as multiple
sclerosis, rheumatoid arthritis and diabetes.
In response, many scientists
have begun pushing to sharply boost the official recommendations
for how much vitamin D everyone should get daily, either
by taking supplements, by eating more food that contains
the nutrient or from the sun -- a major source of vitamin
D.
Suggestions that people get more
sun exposure, however, have sparked an unusually intense,
and sometimes bitter, debate. Skin cancer experts are
alarmed that people will disregard warnings about unprotected
sun exposure, making them more vulnerable to what is
the most common malignancy.
The debate is complicated by
the many uncertainties about vitamin D. Because the
nutrient's apparently widespread functions in the body
are just now being recognized, little research has been
done to try to answer some of the most basic questions,
such as how much is needed for optimal health.
"It's a nutrient that's
been around for a long time, but it's relatively recently
that there's been a lot of evidence emerging that indicates
there's more to vitamin D than we thought," said
Daniel Raiten of the National Institute of Child Health
and Human Development, who organized a recent conference
at the National Institutes of Health (news - web sites)
to identify the most urgent priorities for more research.
Skin produces vitamin D when
hit by ultraviolet light in sunlight. The amount depends
on where people live, skin pigment, age and other factors.
African Americans and other dark-skinned people, and
anyone living in northern latitudes, make far less than
some other groups.
With people spending more time
indoors, covering up and slathering on sunblock when
they are outside, and smog obscuring the sun on many
days, the amount of vitamin D people create naturally
is probably very low, many scientists say.
"Imagine you're a space
alien looking down on Earth. You have these humans who
evolved in the Horn of Africa, as nudists living around
the equator. They would have been getting lots of vitamin
D through their skin. Then they suddenly . . . move
north and put on lots of clothes and block out most
of their capacity to make vitamin D," said Reinhold
Vieth, a University of Toronto vitamin D researcher.
"For me it's a no-brainer. We're not getting enough."
Milk and a few other foods are
fortified with vitamin D, and it occurs naturally in
a few others, such as fatty fish, but most people get
very little through their diets.
"All along the northern
United States, where we have long winters, a lot of
snow, not much sunshine all winter, there is endemic
vitamin D deficiency," said Paresh Dandona of the
State University of New York at Buffalo, who treated
six patients disabled by misdiagnosed vitamin D deficiencies.
A number of studies have found
what could be disturbingly low levels of vitamin D in
many populations, including children, the elderly and
women. One federal study of women nationwide found that
perhaps nearly half of African American women of childbearing
age may be vitamin D deficient.
It remains unclear whether vitamin
D deficiencies are becoming more common because people
are shunning the sun and making other lifestyle changes
or whether it is a long-standing problem that is only
now being recognized.
The first clue came from rickets.
Milk was fortified with vitamin D in the 1930s to eliminate
the disorder, which can cause bowlegs and other bone
malformations. But during the 1990s, doctors in several
cities reported unusual numbers of cases, primarily
in babies being breast-fed and mostly among African
American children. Formula is fortified with vitamin
D, but breast milk contains little, especially among
women with dark skin.
In response, the American Academy
of Pediatrics last spring instructed pediatricians to
prescribe that all children, especially breast-fed babies,
take vitamin D supplements through adolescence.
While it is clear that low vitamin
D levels can lead to rickets in children, muscle problems
in older people and probably brittle bones in the elderly,
the link to other serious illnesses remains far more
tentative. But many specialists say the case has steadily
been getting stronger.
Vitamin D appears to interact
with virtually every tissue in the body. Moreover, the
incidence of certain diseases seems to vary depending
on sun exposure and vitamin D levels.
For example, many cancers, most
notably breast, colon and prostate cancer, seem to increase
the farther you get from the equator, where exposure
to ultraviolet light from the sun is greatest.
"The highest rate of prostate
cancer is among African Americans, followed by countries
in northern Europe. How are blacks like Scandinavians?
They don't look alike, but in some important ways they
have to be alike," said Gary G. Schwartz, a cancer
researcher at Wake Forest University School of Medicine.
"One way that they are alike is both groups have
very low levels of vitamin D."
While there could be many other
explanations, the idea that vitamin D may help prevent
malignancies has been buttressed by animal and laboratory
studies indicating it can act as a brake on cell growth,
preventing the uncontrolled cell division that is cancer.
Similarly, vitamin D appears
to damp down the immune system, and researchers have
also found associations among sun exposure, vitamin
D levels and the incidence of "autoimmune diseases"
such as multiple sclerosis, lupus and diabetes, in which
the immune system attacks the body.
Some studies suggest vitamin
D can reduce blood pressure, which would cut the risk
for heart disease and strokes -- the nation's leading
causes of death. Others suggest that low vitamin D levels
may contribute to depression and other psychiatric conditions.
"It's a major health problem,"
said Michael F. Holick, a Boston University scientist
who is the most prominent proponent of the role of vitamin
D in health. "Everybody has always associated vitamin
D deficiency with rickets in children, and after childhood
you don't have to worry. There's nothing further from
the truth."
Holick and others argue that
instead of the 200 to 600 international units a day
that current recommendations suggest, most people should
be getting at least 1,000 units a day. In a controversial
new book, "The UV Advantage," Holick recommends
exposing the hands, face, arms and legs to the sun for
five to 15 minutes a day a few days a week, which he
says would be enough to generate that amount without
increasing the risk for skin cancer. Many people are
not getting even that amount of sun exposure on a regular
basis, Holick and others say.
"There's no question that
chronic, excessive exposure to sunlight and sunburning
incidents markedly increases your risk for skin cancer.
But there's little evidence out there that if you practice
safe sun exposure, it would increase your risk for skin
cancer or wrinkling," Holick said.
But dermatologists and skin cancer
experts argue that those recommendations are irresponsible
and have little firm scientific support.
"Dr. Holick says vitamin
D is a cure-all magic pill. If everyone took vitamin
D, there would be no more cancer. But there's no evidence
that is true," said James Spencer, vice chairman
of dermatology at Mount Sinai School of Medicine in
New York.
"Ultraviolet light contained
in sunlight causes skin cancer and wrinkles. That's
beyond dispute," Spencer said. "We already
have an epidemic of skin cancer in this country."
Barbara Gilchrest, who chairs
the dermatology department at the Boston University
School of Medicine, said she asked Holick to resign
his position in her department in February because of
his views and because he receives some funding from
the tanning-parlor industry. "He has, in my opinion,
an enormous conflict of interest that he refuses to
acknowledge," Gilchrest said.
Holick, who kept his other academic
positions at the university, acknowledges he receives
funding from the tanning industry, but he says it is
a small portion of his budget and comes with no strings
attached. "The dermatologists get a lot of money
from the sunscreen industry and no one ever questions
them about that," he said.
Many experts who believe vitamin
D deficiencies play an important role in a range of
diseases say people can get enough safely by taking
vitamin D supplements, sidestepping the contentious
sunlight debate.
"There's a lot of emotion
in this fight, which is unfortunate," said Hector
F. DeLuca, who studies vitamin D at the University of
Wisconsin at Madison. "This is a very important
issue. We really need to address two important questions:
Are we getting enough vitamin D? I believe we are not.
The other one is: What's the best way to get it? That's
a matter of debate."
Others, meanwhile, say much more
research is needed to figure out how much vitamin D
people need and the best way to get it.
"We're a long way from making
any definitive statement that Group X has a serious
problem," NIH's Raiten said. "The evidence
seems to imply that we need to look at it carefully,
but I don't think we're in a position of being able
to make any specific recommendations."
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