A high level of vitamin D in the blood can reduce breast cancer risk by half. Edward Gorham, a professor of family and preventive medicine at the Moores UCSD Cancer Center, and colleagues analyzed data from two previous studies on the response to vitamin D among 1,760 people. The researchers divided participants into five groups based on vitamin D levels. The study found that participants with the lowest vitamin D levels had the highest incidence of breast cancer, while breast cancer incidence among participants who took 2,000 international units of vitamin D daily decreased by half.

The researchers recommend that people take 2,000 IUs of vitamin D daily.

Vitamin D and breast cancer, Journal of Steroid Biochemistry and Molecular Biology