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Latest Vitamin D News from the UV
foundation
 
New
Readers Digest Article September 2006
The Miracle Vitamin
New
evidence shows that getting enough D may be the most important thing you can
do for your health.
By Paula Dranov
From
Reader's Digest
September
2006
More
Time in the Sun
You know
the usual prescription for good health: a balanced diet with lots of fruits
and vegetables, regular exercise, no smoking. Now add this: Spend a little
more time in the sun.
Huh?
That may sound like medical heresy. After all, we've been warned for decades
about the dangers of the sun: wrinkles, age spots and the increasing threat of
skin cancer. But new and impressive medical evidence suggests that sunlight is
beneficial. The vitamin D it prompts our bodies to make may prevent cancer,
protect against heart disease and ward off a long list of disorders such as
multiple sclerosis, rheumatoid arthritis, diabetes and gum disease. It is even
showing promise as a treatment for heart disease and some cancers.
Long recognized as vitally important for bone building (it's needed for
calcium absorption),
vitamin D
has now achieved superstar status among
nutrients. While all doctors may not agree, many experts are confident enough
of its wide-ranging powers to urge that we get much more of it, from the sun
and from supplements, as even the best diet in the world may not give us
enough.
"Deficiencies have been
found in people across the age spectrum, from babies with the bone-weakening
disease rickets to the elderly in nursing homes," says Catherine Gordon, MD, a
pediatric bone specialist at Children's Hospital Boston.
When she tested 307 healthy teenagers, Dr. Gordon found that 24 percent were
vitamin D deficient. When measured against the higher blood levels experts now
say we need for good health, 42 percent of the young people fell short.
Similar results have been found among adults of all ages. "Worldwide, one
billion people are vitamin D deficient," explains Dr. Holick.
Check out the
current vitamin D guidelines and find out
which foods are its best sources.
Dr. Holick and others now prescribe at least 1000 IU daily from the sun,
supplements or food. A diet designed to give you 1000 IU of D daily would be
pretty monotonous (mostly milk, juice and cereal that have been fortified,
plus oily fish and cod liver oil), so the alternatives are the sun and
supplements.
Excess vitamin D can also dangerously elevate calcium levels,
causing confusion and bizarre behavior. However, you can't overdose on vitamin
D from the sun. Once the skin absorbs enough UVB rays to make D, the
conversion process shuts down.
Refer to the Sep 2006 Readers Digest Issue for more facts
Readers Digest June 2003 Cover Story
Reprinted from Reader's Digest,
June 2003 edition. The
Healing Vitamin
Are you getting enough?
Wilson Riley didn't know what ailed
his baby son, but by the time the boy was one, Riley was sure something wasn't
right. "His head was growing, but his body was really small," Riley recalls. At
Boston Medical Center, the doctor told him his son Kuool had rickets - a
bone-bending disease caused by vitamin D deficiency.
Looking back a century and more, the
slums of Boston, New York, and London teemed with children whose weak, spindly
limbs and bowed legs testified to their vitamin D deficiency. (Tiny Tim, the
character in Dickens's novel A Christmas Carol, was a likely case.) The disease
all but disappeared after the 1920's, when doctors realized it could be cured by
sun exposure, and farmers began fortifying milk with vitamin D.
But lately the malady has been making a
comeback. That's bad, and not just for kids, according to Boston University
medical school professor Michael Holick, who's spend the last 30 years
researching the subject. He believes we're living amid an unrecognized epidemic
of vitamin D deficiency. And nowadays, scientists are linking low levels of D to
cancer, hypertension, diabetes and osteoporosis. "More and more evidence is
mounting that vitamin D plays an absolutely pivotal role in all aspects of human
health," says Holick.
That's a major shift. Researchers used to
think D's main value was in building strong bones. But new research shows that
this humble nutrient is far more versatile. Unlike other vitamins, D isn't found
in much we eat - aside from fortified milk and cold-water fish like mackerel and
salmon. Instead, most is supplied by the sun. A D-related hormone in the skin
soaks up the ultraviolet rays in sunlight and travels to the liver and the
kidneys, where it picks up extra molecules of oxygen and hydrogen. This process
transforms the "pre-vitamin" D into a potent hormone called calcitriol. Part of
the evolving understanding of this nutrient is that scientists now think many
tissues in the body - not just the liver and kidneys - can convert the
pre-vitamin D to make their own disease-fighting calcitriol.
Let the sun bake your unprotected arms
and face for few minutes, and you'll make all the D you need - it sounds simple,
though a touch sinful. But combine our indoor lifestyle, sun-blocking pollution,
and the fact that even sunscreen with an SPF of 8 reduces D absorption to
virtually nil, and many of us end up falling short, says Holick. Deficiency
seems to be rampant among Americans living above the 40th parallel - line that
cuts from Philadelphia to Columbus, Ohio, past Denver and through Northern
California. Sunshine is so scarce during Boston winters, Holick says, that "you
could stand outside naked from the time the sun rises till it sets and you won't
make any D."
Without sunlight, the body will run
through its reserves of the vitamin within a few weeks. In studies of people
living in the Northeast, anywhere from 20 to 60 percent of those over age 50 are
low on D. The elderly tend to be at higher risk because their D-making machinery
is less efficient.
Also, at elevated risk are African
Americans, since having darker skin makes absorbing UV rays harder. Doctors at
the Centers for Disease Control and Prevention recently found the 42 percent of
African American women of childbearing age were deficient.
One startling result of the growing D
deficiency is more and more rickets cases each year. Doting parents are doing
exactly what they should: breast-feeding their infants and keeping them out of
the sun. For much of his first year, Kuool Riley was nursed - not much D there.
(Experts recommend that breast-feeding mothers should consult their pediatrician
about D supplements.) And the skies over Boston were generally overcast. "When
we took him outside, that little bit of sun clearly wasn't enough to do
anything," recalls his father, Wilson Riley. After doses of vitamin D and
various other therapies, the boy is now a healthy kindergartner.
But what really worries Holick and others
is what Kuool's deficiency may represent: huge chunks of the world's population
living with a chronic lack of D that boosts the risk of serious illnesses. At
the top of the list?
Cancer
The cancer theory got its legs in 1980
after Frank and Cedric Garland, epidemiologists who are also brothers, were
struck by maps showing that the rate of colon cancer was about twice as high in
the cloudy Northeast as in the Sunbelt. The pattern not have been clearer,
recalls Cedric Garland, now a professor at the University of California, San
Diego. Blue zones indicated low rates of cancer, and red, yellow and white
represented average to above average rates, explains Garland. "South of the
Mason-Dixon line was all blue, and everything above it was red, yellow and
white." The Garlands were the first to suggest that differing D levels might
account for the phenomenon. Later studies supported their hunch: People who
consumed the most vitamin D or had the highest levels of D in their blood had a
lower risk of colon cancer.
Researchers are also probing links
between prostate, breast and ovarian cancers and a lack of sunshine and D.
Indeed, scientists at the National Cancer Institute recently surveyed death
certificates in 24 states and found the chances of dying from any of those
cancers was reduced by 10 to 27 percent for people in the sunniest areas.
The idea makes sense biologically,
explains Gary Schwartz, and epidemiologist at Wake Forest University School of
Medicine who has studied the role of D in prostate cancer. Prostate cells, he
has shown, produce the hormone calcitriol, which can act as a brake on cell
growth. When the cells can't get enough of vitamin D's precursor to make
calcitriol, it's as if the brake lines are cut. The cells can multiply
uncontrollably, and cancer results.
Other experts are not yet convinced.
"It's a reasonable hypothesis, but not all studies show an association between
sunshine, D and cancer," says Donald L. Trump, chairman of the department of
medicine at Roswell Park Cancer Institute in Buffalo. "The epidemiology is very
suggestive," says Marji Mccullough of the American Cancer Society. But, she
adds, lack of sunshine and D aren't the only explanations for the geography of
cancer. "People may have other risk factors."
Still, Gary Schwartz is convinced enough
by the data that he is not only administering but also participating in a study
in which healthy men are taking high doses of vitamin D to see if it prevents
prostate cancer.
Diabetes
In Finland, where the sun shows its face
for only a few hours a day during the winter, the natives have the world's
highest incidence of Type 1 diabetes. But Scandinavian researchers there have
found that giving infants, or even pregnant women, vitamin D reduces risk for
the disease. In one study tracking 10,000 children, researchers found that those
who got regular doses of vitamin D as infants were about 80 percent less likely
to later develop Type 1 diabetes than those who did not get enough. Animal
studies offer support: Mice bred to develop diabetes are far less likely to get
it if they are given vitamin D from birth. It's not clear how D does the job.
But Holick and others point out that Type 1 diabetes is an autoimmune disease.
In research, D can suppress certain immune cells, so the vitamin may help by
preventing destruction of the cells that produce insulin.
Hypertension
It's long been known that a population's
average blood pressure rises the farther the country is from the equator. That's
not just a matter of the laid-back tropics versus the urban grind, according
Holick. He recruited 18 volunteers with mild hypertension and put them under UVB
lights for at least six minutes three times a week. After six weeks, the amount
of D in their systems had more than doubled and their blood pressure had dropped
significantly - to normal for some. The lights may work, says Holick, because
they boost calcitriol production by the kidneys, and calcitriol tamps down
enzymes that cause blood vessels to constrict, a major cause of high blood
pressure.
Osteoporosis
At conferences, Holick likes to make his
point about the importance of D to the bones by showing pictures of his
daughter's pet iguana. Without regular doses of UVB rays, the lizard's bones
start to break down. We're not any different, says Holick. In the intricate
ballad of calcium regulation, when D goes missing, another hormone, parathyroid
hormone, builds up and starts pulling calcium out of the skeleton.
One result is the bone-brittling disease
osteoporosis. Holick believes the high rates of osteoporosis among the elderly
can be partly traced to the fact that many spend little time outside and they're
diligent sunscreen wearers. Indeed, studies suggest that 30 to 40 percent of
American and British elders with hip fractures were low on D. The problem could
be remedied with the same ultraviolet lights that iguana owners use for their
pets. "We don't do this for nursing home residents," Holick says, "but we'll
spend 40 bucks for lights for an iguana."
How Much D?
The dangers of not getting enough vitamin
D are so great that experts say people should take a blood test for D levels
once a year - just as they check their cholesterol regularly.
Current daily recommendations for vitamin
D suggest people under the age of 50 get 200 IUs a day; 51- to 60- year-olds aim
for 400 IUs; for those 70 and over, 600 IUs. That's enough to keep bones
healthy, but Holick and others believe we need even more to avoid other
diseases. In the absence of sunlight, the daily dose may be more on the order of
800 IUs to 1000 IUs a day. (More than 2000 IUs can be harmful, producing a toxic
buildup of calcium in the bloodstream.)
But getting 800 IUs isn't too hard to
achieve. An 8-ounce cup of milk contains almost 100 IUs. For the lactose
intolerant or those who don't like dairy, Minute Maid offers D-fortified orange
juice. D supplements are easy to find, usually packaged with calcium.
Better still, get outside. All it takes
is 10-20 minutes a day - without sunscreen.
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