University of California at San Diego Medical Center

 

Epidemiologists at Johns Hopkins University discovered in the late 1980's and the University of California San Diego in the 1990's, that women who live in sunny places are relatively immune to breast cancer.

 

On the other hand, those who live in places with long winters with little sun, such as Iceland, Finland, the Scandinavian Countries, the British Isles, and, in the Southern Hemisphere, New Zealand have extremely high rates. This pattern in both hemispheres could not be explained persuasively by dietary differences.

Within countries such as the US, Italy and the former USSR, death rates from breast cancer are markedly higher in the North than the South. In the US, the death rate from breast cancer is lowest in sunny Hawaii. In Italy it is lowest in Sicily, the sunniest province. In the USSR it was the sunniest southern republics that had the lowest incidence rates of breast cancer. The same pattern has been found in other countries.

 

Studies of individuals then showed that women with lower levels of vitamin D metabolite in the their blood serum had much higher incidence rates of breast cancer. That vitamin D metabolite is called 25-hydroxyvitamin D. It's the main circulating and storage form of vitamin D, and is the standard measure of vitamin D status. The effect is profound for adenocarcinoma of the breast, the most common type of breast cancer that accounts for 80% of US cases.

 

During the next few weeks we will explore the type of vitamin D, and the blood serum concentration of 25-hydroxyvitamin D needed to prevent the majority of breast cancer or convert the rest to a mild disease that will not threaten the life of patients who are given standard care combined with appropriate vitamin D supplementation.