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Science Forum Index » Medicine - Cancer Forum » Ovarian cancer rates lower in sunny latitudes
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| Roman Bystrianyk |
 Posted: Fri Nov 17, 2006 1:46 pm |
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Guest
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Amy Norton, "Ovarian cancer rates lower in sunny latitudes", Scientific
American, November 16, 2006,
Link:
http://www.sciam.com/article.cfm?chanID=sa003&articleID=9D58963592071DBF38A0FA114269959C
Women in the sunnier regions of the world have a much lower risk of
ovarian cancer than those who dwell in colder climates, a new study has
found.
The findings, say researchers, suggest that sun exposure -- and, more
precisely, vitamin D production in the body -- help prevent this
cancer.
The study, which appears in the December issue of the American Journal
of Preventive Medicine, is the latest to tie latitude to cancer risk.
Others have found that rates of breast cancer and colon cancer, for
example, are higher among people living in higher latitudes, where
annual sun exposure is limited.
The theory is that vitamin D explains the link. Sunlight triggers
vitamin D synthesis in the skin, so a person's stores of the vitamin
depend, in part, on where he or she lives. Moreover, a growing number
of studies have linked vitamin D intake and vitamin D levels in the
blood to cancer risk.
One recent study found that adults who took 400 IU of vitamin D per day
were half as likely as people who took no vitamin D supplements to
develop pancreatic cancer.
Lab research has also shown that the vitamin helps thwart cancer cell
growth and proliferation.
It's particularly important to find ways to lower ovarian cancer risk
because there's no good way to detect it early, said Dr. Cedric F.
Garland of the University of California San Diego, the lead author of
the new study.
To investigate the possible role of sun exposure in ovarian cancer, he
and his colleagues examined data on ovarian cancer rates in 175
countries and correlated it with information on latitude, UV radiation
and atmospheric levels of ozone -- which affects UV transmission.
Overall, Garland's team found, ovarian cancer rates were highest in
higher-latitude regions in both hemispheres. In addition, greater UV
exposure and lower ozone levels were both linked to lower ovarian
cancer rates.
The findings show only an association between latitude and ovarian
cancer, and not that vitamin D fights the disease. Many other factors,
from genes to lifestyle habits to reproductive choices, differ among
women living in low- and high-latitude nations -- with countries
farther from the equator being more developed and affluent in general.
And no one is recommending that women bask in the sun, or move to
Florida, to prevent ovarian cancer, Garland said. "We don't want anyone
to burn," he advised.
However, the body of evidence on cancer and vitamin D suggests that
modest sun exposure and use of vitamin D supplements could offer a
cancer defense, according to the researcher.
A person with medium-tone skin, he said, could get enough vitamin D by
spending about 15 minutes in the sun each day, with 50 percent of the
skin exposed -- less time for a fair-skinned person, more for someone
with dark skin.
But since many people get little sun, Garland recommended that adults
take 2,000 IU of vitamin D a day, which is the "tolerable upper intake
level" set by U.S. health officials.
That limit exists because of the risk of vitamin D toxicity, which
causes elevated calcium levels in the blood and problems such as
nausea, weight loss, fatigue and kidney dysfunction.
SOURCE: American Journal of Preventive Medicine, December 2006. |
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| pc55 |
| Posted: Fri Nov 17, 2006 6:21 pm |
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Guest
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Roman Bystrianyk wrote:
This study is not surprising, considering that Vit D deficiency is
associated with higher cancer rates - all types! However, it calls for
a couple of comments:
a) Vit D deficiency occurs in the south too. Just because cancer rates
are lower, doesn't mean that D intake is optimal. In the north, people
stay indoors in the winter, but in the south, the same may hold in the
hotest months. We can get our D with three 20-minute sessions per week
(longer for dark skin), but a month or two of sun avoidance will
severely diminish circulating calcidiol. Sun block will stop UV
generation of D3. Supplementation is safest bet.
b) toxicity issues are always raised, but experts gnerally say 400 IU
is too low & 1,000 IU is more realistic. A prostate study puts the
number much higher. White-skinned youngsters can generate 20,000 IU in
30 minutes at the beach. You never hear of vitamin D toxicity issues
from the sun. Still, 2,000 IU is a gutsy recommendation. I have PC &
take 5,000 IU daily without toxic side effects. I wouldn't recommend
that for healthy people, but the evidence indicate there isn't much
risk.
c) I believe that the synthetic calciferol is best, since it is
identical to what our body makes. Vit D2 isn't so good a choice. Vit
D3 from fish oil is worse, since a high dose requires a lot of oil &
comes with a huge amount of Vit A.
-Patrick |
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