[pct-l] Sunlight -- second opinion / thought

[Tortoise73 at charter.net (John Mertes)]

Here's another take on the sun issue. Not the last word, but maybe a 
reason to not be so afraid of the sun.

Tortoise



-------- Original Message --------

*Research sheds light on value of basking in sun*

*By Marilynn Marchione, Associated Press*
*May 22, 2005*

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.
Because sunscreen blocks vitamin D's production, some scientists are 
questioning the long-standing advice to always use it.

The reason is that vitamin D increasingly seems important for preventing 
and even treating many types of cancer. In the past 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, and it's hard to get from 
food and fortified milk; 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 a few times a week without 
sunscreen -- is a healthy thing to do.

One is Dr. Edward Giovannucci, a Harvard University professor of 
medicine and nutrition who laid out his case in a recent lecture at a 
major cancer research meeting.

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 problem, he said, is a lack of consensus on how much vitamin D is 
needed or the best way to get it. 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 people might overdo it.

"People tend to go overboard with even a hint of encouragement to get 
more sun exposure," Thun said, noting 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, but diet accounts for 
very little of the vitamin D circulating in blood, Giovannucci said.

Most supplements 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 older than 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.