A new meta-analysis study explored the current research on vitamin D and breast cancer (as well as colorectal cancer). For this meta-analysis, data from multiple studies were pulled together and analyzed as a whole group in an attempt to determine a dose-response relationship between vitamin D and breast cancer risk. Compared to the lowest blood levels of vitamin D measured, vitamin D levels of about 31 ng/ml (78 nmol/L) reduced breast cancer risk by 50%. Dose-response analysis further suggested that an optimum blood level of vitamin D was above 40 ng/ml (100 nmol/L). However, the dose-response relationship was not linear, instead showing a slowing in benefit. For example, while higher blood levels continued to show a greater breast cancer risk reduction, doubling the blood levels of vitamin D did not double breast cancer risk reduction.
This new meta-analysis continues to shed a positive light on the benefits of vitamin D for reducing breast cancer risk. Average blood levels in most U.S. populations are typically insufficient, so improved awareness and education regarding the potential health benefits of vitamin D are important. Based on current information, the greatest breast cancer risk reducing benefits can be obtained by targeting vitamin D blood levels of 30 - 60 ng/ml (75 - 150 nmol/L).