Calcium and breast cancer:
Chung, et al reviewed a number of studies on health outcomes by subjects which consumed calcium and vitamin D. It was found that adequate calcium intakes in premenopausal women was associated with a decreased risk of breast cancer. (21)
Vitamin D and cancer:
Vitamin D and cancer mortality:
Investigators followed a total of 1,194 men over a median duration of 12.7 years in a longitudinal study looking at the link between blood levels of vitamin D and mortality. They looked at vitamin D levels and cancer-related as well as all-cause mortality. There was a clear U-shaped curve when looking at the relationship between vitamin D levels and all-cause mortality along with cancer-related mortality, meaning the risk of mortality was significantly increased at both low and high blood levels of vitamin D. In this study, the range with the lowest mortality was about a vitamin D concentration of 24 to 34 ng/ml (60 to 85 nMol/L), which approximately translates to a vitamin D dose of 2000 IU/d. In general, the biggest drop in overall death rates were seen when subjects went from being vitamin D deficient to reaching adequate levels. However, too much vitamin D translated into a gradual increase of mortality rate with cancer deaths rising significantly for the highest levels of vitamin D intake. Overall mortality was increased by 50–60% among subjects in the lowest 10% and highest 5% of the vitamin D distribution. The ideal vitamin D dose according to findings in this study is 2000 IU per day for adults. (22)