A new prospective study has reported that higher levels of circulating vitamin D are associated with reduced risk of breast cancer. The study was designed to investigate the link between blood levels of vitamin D and risk of breast cancer by menopausal status. The study included 636 French breast cancer cases and 1,272 cancer-free controls. Cases and controls were matched based on age, menopausal status at blood collection, age at menopause, and center and year of blood draw.

Overall, women in the highest third of 25(OH) vitamin D3 serum concentrations were found to have a 27% lower risk of breast cancer than those in the lowest third. When analyzed by age, women who were younger than 53 when their blood was drawn and who were in the highest third of circulating vitamin D had a 40% lower risk of breast cancer than those in the lowest third. However, when the analysis was restricted to premenopausal women, while breast cancer risk was also found to be lower for those in the highest third of vitamin D, the results were not statistically significant. The authors conclude that high 25(OH) vitamin D3 serum concentrations are associated with decreased risk of breast cancer, especially in younger women, although they were unable to confirm a direct influence of age or menopausal status.

Please see our article on vitamin D for more information on taking vitamin D during and after breast cancer treatment.