Certain amounts of vitamin D may
be able to prevent up to half of breast cancer cases and
two-thirds of colorectal cancer cases in the United States,
according to two studies by researchers at the Moores
Cancer Center at the University of California, San Diego,
and colleagues at other centers.
In one study, the researchers reviewed two previous studies
of 1,760 women and found that those with the highest blood
levels of 25-hydroxyvitamin D, or 25(OH)D, had the lowest
risk of breast cancer.
"The data were very clear, showing that individuals in
the group with the lowest blood levels (less than 13 nanograms
of 25(OH)D per milliliter) had the highest rates of breast
cancer, and the breast cancer rates dropped as the blood
levels of 25-hydroxyvitamin D increased," study co-author
Cedric Garland said in a prepared statement.
"The serum level associated with a 50 percent reduction
in risk could be maintained by taking 2,000 international
units of vitamin D3 daily, plus, when the weather permits,
spending 10 to 15 minutes a day in the sun," Garland said.
The study appears online in the current issue of the
Journal of Steroid Biochemistry and Molecular Biology.
In the second study, researchers reviewed data from 1,448
people who took part in five previous colorectal cancer
"Through this meta-analysis, we found that raising the
serum level of 25-hydroxyvitamin D to 34 ng/ml would reduce
the incidence rates of colorectal cancer by half," study
co-author Edward G. Gorham said in a prepared statement.
"We project a two-thirds reduction in incidence with
serum levels of 46ng/ml, which corresponds to a daily
intake of 2,000 IU of vitamin D3. This would be best achieved
with a combination of diet, supplements and 10 to 15 minutes
per day in the sun," Gorham said.
The study was published online Feb. 6 in the American
Journal of Preventive Medicine.