[ RadSafe ] Sunshine Vitamin

[Jim Hoerner]

I apologize if this has already been posted; I get the digest (and quite a 
bit of exercise, fresh produce, and sun)...

Scientists Say Sunshine May Prevent Cancer


By MARILYNN MARCHIONE, AP Medical Writer Sun May 22, 5:09 AM ET

Scientists are excited about a vitamin again. But unlike fads that sizzled
and fizzled, the evidence this time is strong and keeps growing. If it bears
out, it will challenge one of medicine's most fundamental beliefs: that
people need to coat themselves with sunscreen whenever they're in the sun.
Doing that may actually contribute to far more cancer deaths than it
prevents, some researchers think.

The vitamin is D, nicknamed the "sunshine vitamin" because the skin makes it
from ultraviolet rays. Sunscreen blocks its production, but dermatologists
and health agencies have long preached that such lotions are needed to
prevent skin cancer. Now some scientists are questioning that advice. The
reason is that vitamin D increasingly seems important for preventing and
even treating many types of cancer.

In the last three months alone, four separate studies found it helped
protect against lymphoma and cancers of the prostate, lung and, ironically,
the skin. The strongest evidence is for colon cancer.

Many people aren't getting enough vitamin D. It's hard to do from food and
fortified milk alone, and supplements are problematic.

So the thinking is this: Even if too much sun leads to skin cancer, which is
rarely deadly, too little sun may be worse.

No one is suggesting that people fry on a beach. But many scientists believe
that "safe sun" — 15 minutes or so a few times a week without sunscreen — is
not only possible but helpful to health.

One is Dr. Edward Giovannucci, a Harvard University professor of medicine
and nutrition who laid out his case in a keynote lecture at a recent
American Association for Cancer Research meeting in Anaheim, Calif.

His research suggests that vitamin D might help prevent 30 deaths for each
one caused by skin cancer.

"I would challenge anyone to find an area or nutrient or any factor that has
such consistent anti-cancer benefits as vitamin D," Giovannucci told the
cancer scientists. "The data are really quite remarkable."

The talk so impressed the
American Cancer Society's chief epidemiologist, Dr. Michael Thun, that the
society is reviewing its sun protection guidelines. "There is now intriguing
evidence that vitamin D may have a role in the prevention as well as
treatment of certain cancers," Thun said.

Even some dermatologists may be coming around. "I find the evidence to be
mounting and increasingly compelling," said Dr. Allan Halpern, dermatology
chief at Memorial Sloan-Kettering Cancer Center in New York, who advises
several cancer groups.

The dilemma, he said, is a lack of consensus on how much vitamin D is needed
or the best way to get it.

No source is ideal. Even if sunshine were to be recommended, the amount
needed would depend on the season, time of day, where a person lives, skin
color and other factors. Thun and others worry that folks might overdo it.

"People tend to go overboard with even a hint of encouragement to get more
sun exposure," Thun said, adding that he'd prefer people get more of the
nutrient from food or pills.

But this is difficult. Vitamin D occurs naturally in salmon, tuna and other
oily fish, and is routinely added to milk. However, diet accounts for very
little of the vitamin D circulating in blood, Giovannucci said.

Supplements contain the nutrient, but most use an old form — D-2 — that is
far less potent than the more desirable D-3. Multivitamins typically contain
only small amounts of D-2 and include vitamin A, which offsets many of D's
benefits.

As a result, pills might not raise vitamin D levels much at all.

Government advisers can't even agree on an RDA, or recommended daily
allowance for vitamin D. Instead, they say "adequate intake" is 200
international units a day up to age 50, 400 IUs for ages 50 to 70, and 600
IUs for people over 70.

Many scientists think adults need 1,000 IUs a day. Giovannucci's research
suggests 1,500 IUs might be needed to significantly curb cancer.

How vitamin D may do this is still under study, but there are lots of
reasons to think it can:

_Several studies observing large groups of people found that those with
higher vitamin D levels also had lower rates of cancer. For some of these
studies, doctors had blood samples to measure vitamin D, making the findings
particularly strong. Even so, these studies aren't the gold standard of
medical research — a comparison over many years of a large group of people
who were given the vitamin with a large group who didn't take it. In the
past, the best research has deflated health claims involving other
nutrients, including vitamin E and beta carotene.

_Lab and animal studies show that vitamin D stifles abnormal cell growth,
helps cells die when they are supposed to, and curbs formation of blood
vessels that feed tumors.

_Cancer is more common in the elderly, and the skin makes less vitamin D as
people age.

_Blacks have higher rates of cancer than whites and more pigment in their
skin, which prevents them from making much vitamin D.

_Vitamin D gets trapped in fat, so obese people have lower blood levels of
D. They also have higher rates of cancer.

_Diabetics, too, are prone to cancer, and their damaged kidneys have trouble
converting vitamin D into a form the body can use.

_People in the northeastern United States and northerly regions of the globe
like Scandinavia have higher cancer rates than those who get more sunshine
year-round.

During short winter days, the sun's rays come in at too oblique an angle to
spur the skin

to make vitamin D. That is why nutrition experts think vitamin D-3
supplements may be especially helpful during winter, and for dark-skinned
people all the time.

But too much of the pill variety can cause a dangerous buildup of calcium in
the body. The government says 2,000 IUs is the upper daily limit for anyone
over a year old.

On the other hand, D from sunshine has no such limit. It's almost impossible
to overdose when getting it this way. However, it is possible to get skin
cancer. And this is where the dermatology establishment and Dr. Michael
Holick part company.

Thirty years ago, Holick helped make the landmark discovery of how vitamin D
works. Until last year, he was chief of endocrinology, nutrition and
diabetes and a professor of dermatology at Boston University. Then he
published a book, "The UV Advantage," urging people to get enough sunlight
to make vitamin D.

"I am advocating common sense," not prolonged sunbathing or tanning salons,
Holick said.

Skin cancer is rarely fatal, he notes. The most deadly form, melanoma,
accounts for only 7,770 of the 570,280 cancer deaths expected to occur in
the United States this year.

More than 1 million milder forms of skin cancer will occur, and these are
the ones tied to chronic or prolonged suntanning.

Repeated sunburns — especially in childhood and among redheads and very
fair-skinned people — have been linked to melanoma, but there is no credible
scientific evidence that moderate sun exposure causes it, Holick contends.

"The problem has been that the American Academy of Dermatology has been
unchallenged for 20 years," he says. "They have brainwashed the public at
every level."

The head of Holick's department, Dr. Barbara Gilchrest, called his book an
embarrassment and stripped him of his dermatology professorship, although he
kept his other posts.

She also faulted his industry ties. Holick said the school has received
$150,000 in grants from the Indoor Tanning Association for his research, far
less than the consulting deals and grants that other scientists routinely
take from drug companies.

In fact, industry has spent money attacking him. One such statement from the
Sun Safety Alliance, funded in part by Coppertone and drug store chains,
declared that "sunning to prevent vitamin D deficiency is like smoking to
combat anxiety."

Earlier this month, the dermatology academy launched a "Don't Seek the Sun"
campaign calling any advice to get sun "irresponsible." It quoted Dr.
Vincent DeLeo, a Columbia University dermatologist, as saying: "Under no
circumstances should anyone be misled into thinking that natural sunlight or
tanning beds are better sources of vitamin D than foods or nutritional
supplements."

That opinion is hardly unanimous, though, even among dermatologists.

"The statement that 'no sun exposure is good' I don't think is correct
anymore," said Dr. Henry Lim, chairman of dermatology at Henry Ford Health
System in Detroit and an academy vice president.

Some wonder if vitamin D may turn out to be like another vitamin, folate.
High intake of it was once thought to be important mostly for pregnant
women, to prevent birth defects. However, since food makers began adding
extra folate to flour in 1998, heart disease, stroke, blood pressure, colon
cancer and osteoporosis have all fallen, suggesting the general public may
have been folate-deficient after all.

With vitamin D, "some people believe that it is a partial deficiency that
increases the cancer risk," said Hector DeLuca, a University of
Wisconsin-Madison biochemist who did landmark studies on the nutrient.

About a dozen major studies are under way to test vitamin D's ability to
ward off cancer, said Dr. Peter Greenwald, chief of cancer prevention for
the National Cancer Institute. Several others are testing its potential to 
treat
the disease. Two recent studies reported encouraging signs in prostate and
lung cancer.

As for sunshine, experts recommend moderation until more evidence is in
hand.

"The skin can handle it, just like the liver can handle alcohol," said Dr.
James Leyden,

professor emeritus of dermatology at the University of Pennsylvania, who has
consulted for sunscreen makers.

"I like to have wine with dinner, but I don't think I should drink four
bottles a day."

___

On the Net:

Government information:

http://ods.od.nih.gov/factsheets/vitamind.asp

--------------------------

http://news.yahoo.com/s/ap/sunshine___cancer

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