- Nutrition researchers are pushing for
a big increase in the daily recommended dose of vitamin D. Dozens of recent
studies suggest that deficiencies of the sunshine vitamin make people more
vulnerable to everything from fractures to certain cancers and diabetes.
-
- Dr. Ken Cooper is an early adopter of
higher dose vitamin D. He directs The Cooper Institute, a Dallas-based
nonprofit research organization, which studies vitamins and markets doses
and combinations backed by science.
-
- Sun Not Always a Sufficient Source
-
- "We used to think that we got all
the vitamin D we needed daily by exposure to the sun," says Cooper.
But studies show 65 percent of Americans don't get enough. The sun's rays
aren't strong enough in winter. And in the warmer months, many people wear
sunscreen or cover up in work clothes.
-
- Researchers say 10 to 15 minutes of sun
exposure in the midday sun during the summer is adequate. But it can be
tough to get in, says Dr. Beth Dawson Hughes, director of the Bone Metabolism
Laboratory at Tufts University.
-
- "I walked to and from the clinic
with my hands and arms exposed. But it didn't take me 10 minutes,"
she says. "So I'd say I have not gotten my daily dose today."
-
- D Helps More than Bones
-
- Dawson-Hughes recommends vitamin D supplements
to her patients. Studies going back to the 1980s have shown that a combination
of D and calcium supplements can reduce the risk of bone fractures.
-
- "Now we see that D affects muscle
performance, muscle strength and the risk of falling," says Dawson-Hughes.
-
- The key to effective vitamin D supplementation
lies in taking adequate doses. Osteoporosis clinics usually take blood
samples from patients to determine how much D is needed to restore optimal
levels.
-
- In some fracture and bone health studies,
patients see benefits with supplements of 800 international units of vitamin
D. This is double the amount currently recommended by the government-sponsored
Food and Nutrition Board of the National Academy of Sciences. This group
set the standards that many makers of supplements and multivitamins follow.
-
- The benefits of vitamin D seem to extend
far beyond bone health, says Dr. Walter Willett of the Harvard School of
Public Health.
-
- "I think at this time the case for
raising the recommended level of D intake is very strong," says Willett.
"There are many lines of evidence that people need more vitamin D."
-
- Vitamin D and Cancer Prevention
-
- Take, for instance, cancer prevention.
A few decades ago, researchers found that colon cancer rates were higher
in northern parts of the country where sunlight exposure is lowest.
-
- From this lead, Willett's group at Harvard
designed a study. They took blood samples from 30,000 healthy women to
find out exactly how much D they had in their bodies. The researchers then
followed the women for years to see which ones developed colon cancer.
-
- "We found that women who had the
lowest blood levels (of vitamin D) have double the risk of cancer over
those who had the highest," Willett says.
-
- The study doesn't prove that vitamin
D protects against cancer. But two other lines of evidence help build the
case. Lab researchers doing test-tube and animal studies have found that
vitamin D reduces the rate of cell multiplication.
-
- And recently, scientists have found that
a genetic variation in the vitamin D receptor, which transmits signals
from vitamin D to cells, is associated with risk of breast cancer.
-
- The Case for Increasing D
-
- There's also new work into understanding
how vitamin D may affect the risk of multiple sclerosis, asthma and diabetes.
-
- "We and many other researchers are
seeing that individuals who have higher vitamin D levels have a lower risk
of developing Type 2 diabetes," says Dawson-Hughes.
-
- Researchers have many reasons to be excited
by the accumulating evidence, yet many of their preliminary findings remain
unproven.
-
- Scientists do have new studies to show
that high doses of vitamin D -- up to 4,000 international units per day
-- are not toxic to the body. Some researchers hope to use this evidence
to persuade the Food and Nutrition Board to increase the daily recommended
level to 1,000 IUs per day for adults.
-
- http://WWW.NPR.org/templates/story/story.php?storyId=5503161
-
-
-
- Revealed - The Pill That Prevents Cancer
-
- By Jeremy Laurance
- Health Editor - Independent On Line
-
- A daily dose of vitamin D could cut the
risk of cancers of the breast, colon and ovary by up to a half, a 40-year
review of research has found. The evidence for the protective effect of
the "sunshine vitamin" is so overwhelming that urgent action
must be taken by public health authorities to boost blood levels, say cancer
specialists.
-
- A growing body of evidence in recent
years has shown that lack of vitamin D may have lethal effects. Heart disease,
lung disease, cancer, diabetes, high blood pressure, schizophrenia and
multiple sclerosis are among the conditions in which it is believed to
play a vital role. The vitamin is also essential for bone health and protects
against rickets in children and osteoporosis in the elderly.
-
- Vitamin D is made by the action of sunlight
on the skin, which accounts for 90 per cent of the body's supply. But the
increasing use of sunscreens and the reduced time spent outdoors, especially
by children, has contributed to what many scientists believe is an increasing
problem of vitamin D deficiency.
-
- After assessing almost every scientific
paper published on the link between vitamin D and cancer since the 1960s,
US scientists say that a daily dose of 1,000 international units (25 micrograms)
is needed to maintain health. " The high prevalence of vitamin D deficiency
combined with the discovery of increased risks of certain types of cancer
in those who are deficient, suggest that vitamin D deficiency may account
for several thousand premature deaths from colon, breast, ovarian and other
cancers annually," they say in the online version of the American
Journal of Public Health.
-
- The dose they propose of 1,000IU a day
is two-and-a-half times the current recommended level in the US. In the
UK, there is no official recommended dose but grey skies and short days
from October to March mean 60 per cent of the population has inadequate
blood levels by the end of winter.
-
- The UK Food Standards Agency maintains
that most people should be able to get all the vitamin D they need from
their diet and "by getting a little sun". But the vitamin can
only be stored in the body for 60 days.
-
- High rates of heart disease in Scotland
have been blamed on the weak sunlight and short summers in the north, leading
to low levels of vitamin D. Differences in sunlight may also explain the
higher rates of heart disease in England compared with southern Europe.
Some experts believe the health benefits of the Mediterranean diet may
have as much to do with the sun there as with the regional food.
-
- Countries around the world have begun
to modify their warnings about the dangers of sunbathing, as a result of
the growing research on vitamin D. The Association of Cancer Councils of
Australia acknowledged this year for the first time that some exposure
to the sun was healthy.
-
- Australia is one of the world's sunniest
countries and has among the highest rates of skin cancer. For three decades
it has preached sun avoidance with its "slip, slap, slop" campaign
to cover up and use sunscreen. But in a statement in March, the association
said: "A balance is required between avoiding an increase in the risk
of skin cancer and achieving enough ultraviolet radiation exposure to achieve
adequate vitamin D levels." Bruce Armstrong, the professor of public
health at Sydney University, said: " It is a revolution."
-
- In the latest study, cancer specialists
from the University of San Diego, California, led by Professor Cedric Garland,
reviewed 63 scientific papers on the link between vitamin D and cancer
published between 1966 and 2004. People living in the north-eastern US,
where it is less sunny, and African Americans with darker skins were more
likely to be deficient, researchers found. They also had higher cancer
rates.
-
- The researchers say their finding could
explain why black Americans die sooner from cancer than whites, even after
allowing for differences in income and access to care.
-
- Professor Garland said: "A preponderance
of evidence from the best observational studies... has led to the conclusion
that public health action is needed. Primary prevention of these cancers
has been largely neglected, but we now have proof that the incidence of
colon, breast and ovarian cancer can be reduced dramatically by increasing
the public's intake of vitamin D." Obtaining the necessary level of
vitamin D from diet alone would be difficult and sun exposure carries a
risk of triggering skin cancer. "The easiest and most reliable way
of getting the appropriate amount is from food and a daily supplement,"
they say.
-
- The cost of a vitamin D supplement is
about 4p a day. The UK Food Standards Agency said that taking Vitamin D
supplements of up to 1,000IU was " unlikely to cause harm".
-
- What it can do
- Heart disease
-
- Vitamin D works by lowering insulin resistance,
which is one of the major factors leading to heart disease.
-
- Lung disease
-
- Lung tissue undergoes repair and "remodelling"
in life and, since vitamin D influences the growth of a variety of cell
types, it may play a role in this lung repair process.
-
- Cancers (breast, colon, ovary, prostate)
-
- Vitamin D is believed to play an important
role in regulating the production of cells, a control that is missing in
cancer. It has a protective effect against certain cancers by preventing
overproduction of cells.
-
- Diabetes
-
- In type 1 diabetes the immune system
destroys its own cells. Vitamin D is believed to act as an immunosuppressant.
Researchers believe it may prevent an overly aggressive response from the
immune system.
-
- High blood pressure
-
- Vitamin D is used by the parathyroid
glands that sit on the thyroid gland in the neck. These secrete a hormone
that regulates the body's calcium levels. Calcium, in turn, helps to regulate
blood pressure, although the mechanism is not yet completely understood.
-
- Schizophrenia
-
- The chance of developing schizophrenia
could be linked to how sunny it was in the months before birth. A lack
of sunlight can lead to vitamin D deficiency, which scientists believe
could alter the growth of a child's brain in the womb.
-
- Multiple sclerosis
-
- Lack of vitamin D leads to limited production
of 1.25-dihydroxyvitamin D3, the hormonal form of vitamin D3 which regulates
the immune system, creating a risk for MS.
-
- Rickets and osteoporosis
-
- The vitamin strengthens bones, protecting
against childhood rickets and osteoporosis in the elderly.
-
- A daily dose of vitamin D could cut the
risk of cancers of the breast, colon and ovary by up to a half, a 40-year
review of research has found. The evidence for the protective effect of
the "sunshine vitamin" is so overwhelming that urgent action
must be taken by public health authorities to boost blood levels, say cancer
specialists.
-
- A growing body of evidence in recent
years has shown that lack of vitamin D may have lethal effects. Heart disease,
lung disease, cancer, diabetes, high blood pressure, schizophrenia and
multiple sclerosis are among the conditions in which it is believed to
play a vital role. The vitamin is also essential for bone health and protects
against rickets in children and osteoporosis in the elderly.
-
- Vitamin D is made by the action of sunlight
on the skin, which accounts for 90 per cent of the body's supply. But the
increasing use of sunscreens and the reduced time spent outdoors, especially
by children, has contributed to what many scientists believe is an increasing
problem of vitamin D deficiency.
-
- After assessing almost every scientific
paper published on the link between vitamin D and cancer since the 1960s,
US scientists say that a daily dose of 1,000 international units (25 micrograms)
is needed to maintain health. " The high prevalence of vitamin D deficiency
combined with the discovery of increased risks of certain types of cancer
in those who are deficient, suggest that vitamin D deficiency may account
for several thousand premature deaths from colon, breast, ovarian and other
cancers annually," they say in the online version of the American
Journal of Public Health.
-
- The dose they propose of 1,000IU a day
is two-and-a-half times the current recommended level in the US. In the
UK, there is no official recommended dose but grey skies and short days
from October to March mean 60 per cent of the population has inadequate
blood levels by the end of winter.
-
- The UK Food Standards Agency maintains
that most people should be able to get all the vitamin D they need from
their diet and "by getting a little sun". But the vitamin can
only be stored in the body for 60 days.
-
- High rates of heart disease in Scotland
have been blamed on the weak sunlight and short summers in the north, leading
to low levels of vitamin D. Differences in sunlight may also explain the
higher rates of heart disease in England compared with southern Europe.
Some experts believe the health benefits of the Mediterranean diet may
have as much to do with the sun there as with the regional food.
-
- Countries around the world have begun
to modify their warnings about the dangers of sunbathing, as a result of
the growing research on vitamin D. The Association of Cancer Councils of
Australia acknowledged this year for the first time that some exposure
to the sun was healthy.
-
- Australia is one of the world's sunniest
countries and has among the highest rates of skin cancer. For three decades
it has preached sun avoidance with its "slip, slap, slop" campaign
to cover up and use sunscreen. But in a statement in March, the association
said: "A balance is required between avoiding an increase in the risk
of skin cancer and achieving enough ultraviolet radiation exposure to achieve
adequate vitamin D levels." Bruce Armstrong, the professor of public
health at Sydney University, said: " It is a revolution."
-
- In the latest study, cancer specialists
from the University of San Diego, California, led by Professor Cedric Garland,
reviewed 63 scientific papers on the link between vitamin D and cancer
published between 1966 and 2004. People living in the north-eastern US,
where it is less sunny, and African Americans with darker skins were more
likely to be deficient, researchers found. They also had higher cancer
rates.
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