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Naples Daily News,
Sunday, May 22, 2005
Scientists:
Sunshine may
help fight cancer
By MARILYNN
MARCHIONE
Associated
Press
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, nickname 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 "safesun" - 15 minutes or so a few times a week without sunscreen -
is
not only possible but also 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.
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