Vitamin D May Lower Pancreatic Cancer Risk
Getting the recommended daily dose cut risk by 43 percent, study found
THURSDAY, Sept. 14, 2006 (HealthDay News) -- 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."
There's more on pancreatic cancer at the American Cancer Society.