Women who live in sunnier climates have lower breast cancer rates, a research team from the University of California in San Diego reported Saturday. "The farther a woman lives from the equator, the higher the incidence of breast cancer," said Cedric F. Garland of the UCSD School of Medicine.
"What we've found, in the U.S. and the Soviet Union, is an incidence of breast cancer anywhere from two to three times higher in areas far from the equator," said Garland, who heads the university's Cancer Center Epidemiology Program.
The scientists theorize that the lack of sunlight leads to a deficiency of vitamin D, which has been linked to breast cancer resistance.
The body needs ultraviolet light, a component of sunlight, to utilize vitamin D consumed in food, and the farther away from the equator, the lower the levels of ultraviolet light.
The report was presented at the annual meeting of the American Association for the Advancement of Science.
Consuming more vitamin D can help decrease the odds of contracting breast cancer, the researchers said.
They recommend that women consume 400 international units of vitamin D a day in their diet, compared to the 85 units a day contained in the typical American diet.