The annual meeting of the American Association for Cancer Research held this month featured reports by two groups of scientists who used statistical analysis to determine whether vitamin D, which our bodies make from exposure to sunlight, can help protect against breast cancer.
Studies conducted by researchers in Toronto show that the risk reduction was most apparent among subjects exposed to the highest levels of vitamin D when they were young.
The studies involved interviews with 576 patients who had been diagnosed with breast cancer and 1,135 women who had no cancer. The scientists found significant reductions in breast cancer among those who had worked an outdoor job, had taken part in outdoor activities when young, or consumed cod liver oil or milk.
Working an outdoor job between the ages of 10 and 19 resulted in an estimated 40 percent reduced risk of breast cancer. Frequent outdoor activities between ages 10 to 29 lowered breast cancer risk by an estimated 35 percent.
As far as dietary habits are concerned, the researchers also found that taking cod liver oil between ages 10 and 19 reduced breast cancer risk by about 25 percent, and consuming at least nine glasses of milk every week between the ages of 10 and 29 reduced the risk by 35 percent.
The researchers emphasized that their findings are preliminary estimates of the risk reduction for breast cancer caused by vitamin D. Their next efforts will be to solidify these findings with additional evidence and to determine whether exercising outdoors is associated in any way with breast cancer risk.
Another report by researchers from the University of California, San Diego, found that increasing doses of dietary vitamin D may help prevent breast cancer and that the optimal level of intake of vitamin D for this purpose is more that three times the current average intake for Americans. Major sources of dietary vitamin D are fatty fish, cod liver oil, egg yolks, and vitamin D-fortified foods like milk, cereal, margarine, and butter.
This is exciting news! For women who take their breast health seriously, these findings suggest yet another option to reduce their risk.