Consuming the recommended daily amount of vitamin
D could nearly halve your risk for deadly pancreatic
cancer, new research suggests.
"Individuals in the highest levels of consumption
of vitamin D had a greater than 40 percent reduction
in their risk of pancreatic cancer," said
study co-author Dr. Charles S. Fuchs, an associate
professor and medical oncologist with the Dana-Farber
Cancer Institute, in Boston.
"We really have been struggling to find
effective measures of prevention, so we are very
excited by this effort," he added.
Fuchs' team presented their findings in the September
issue of Cancer Epidemiology Biomarkers & Prevention.
The researchers note that pancreatic cancer is
currently the fourth-leading cause of cancer death
in the Ubited States. Because the disease often
is detected relatively late, survival is very
low. According to the American
Cancer Society, 32,000 new cases of this
silent killer will be diagnosed this year, and
a similar number of Americans will die of the
disease.
There is no known cure or effective treatment,
and to date no specific environmental or dietary
practices other than smoking have been cited as
a contributing factors for pancreatic cancer.
In their study, the researchers analyzed data
from two long-term national studies. One study
was launched in 1976 and the other in 1986. Both
assessed dietary intake among more than 75,000
female registered nurses and almost 47,000 male
health professionals, respectively.
The men were between the ages of 40 and 75, while
the women were between 38 and 65. Beginning in
the mid-1980s, participants completed food-consumption
questionnaires every other year through to 2000.
Vitamin use, smoking and diabetes status, and
cancer history were also tracked over the study
period. Exposure to sun -- a major source of daily
vitamin D -- was not reviewed.
Over the course of the study, 178 women and 187
men were diagnosed with pancreatic cancer.
Vitamin D intake seemed to be related to pancreatic
cancer risk, the researchers found.
Compared to individuals who took in less than
150 International Units (IUs) of vitamin D per
day, those who consumed between 150 to 299 IUs
of the vitamin had a 22 percent reduced risk for
pancreatic malignancy, and those who consumed
between 300-449 IUs/day cut their risk by 43 percent.
The current U.S. recommended daily allowance
(RDA) for vitamin D is 400 IUs per day.
Taking in more than 400 IUs per day of vitamin
D did not result in a further lowering of risk,
the researchers found.
Neither body mass index nor smoking history had
any impact on vitamin D's association with a reduced
pancreatic cancer risk. As well, where a person
lived -- in the sunny south or the less-sunny
north -- had no effect on vitamin D's impact on
pancreatic cancer risk.
Older, more physically active, nonsmoking men
and women were more likely to consume higher doses
of vitamin D, the researchers noted, and almost
everyone who placed in the highest level of vitamin
D intake took a daily multivitamin.
In terms of food, skim milk was the most common
source of vitamin D, providing 19 percent of vitamin
D dietary consumption for both men and women.
Fish provided another 14 percent of the vitamin
among the men and 8 percent among the women.
Fuchs and his colleagues stressed that it remains
unclear whether vitamin D directly reduces pancreatic
cancer risk. It could be that high intake of the
vitamin is merely associated with another, as
yet unidentified, protective behavior.
"It's really the first study of its kind,
so this clearly requires further confirmation,"
said Fuchs.
In the interim, he advised against rushing out
to consume vitamin D supplements.
"One has to be very careful about taking
too much from this in terms of supplemental dosage
recommendations," Fuchs cautioned. "The
biology suggests that even 400 IUs per day may
actually be a relatively low dose [of vitamin
D], and that human beings would benefit from higher
doses in general. But this still needs to be studied
in much greater detail."
Susan Harris, a nutritional epidemiologist with
the Tufts University Jean Mayer Human Nutrition
Research Center on Aging in Boston, agreed that
vitamin D supplementation is a complex issue.
She said supplements do have a role to play in
maintaining health and perhaps even fighting off
cancer.
"We evolved outside in the sun and we're
really built to make vitamin D from sun exposure,
but now that we're in an indoor living population
our exposure is really reduced," she said.
"And dietary sources are often not enough.
So we are really more reliant on supplements."
"But with some nutritional supplements
you can do some actual harm," she advised.
"For example, it's true that most vitamin
D experts now believe that most people should
be consuming as much as 1000 IUs per day. And
if you take a multivitamin you'll get just 400
IUs of vitamin D. But what you don't want to take
is two multivitamins because you get double of
everything else. So you always have to be careful."
