Dietary calcium intake, vitamin D levels, and breast cancer risk: a dose-response analysis of observational studies.

Results from the recent meta-analysis suggested a favorable effect of dietary calcium and vitamin D levels on breast cancer risk. However, the relationship of dietary calcium and vitamin D levels with breast cancer risk is unclear. Thus, the dose-response relationship was assessed by restricted cubic spline model and multivariate random-effect meta-regression. Results suggested that women might suffer from the lowest risk of breast cancer with dietary calcium intake of about 600 mg/day, dietary vitamin D intake of about 400 IU/day, and serum vitamin D levels of about 30 ng/ml.