Every two minutes, a woman will be diagnosed with breast cancer in the United States. This means that over 250,000 new cases of breast cancer will be diagnosed each year. As this disease is the second leading cause of death in women, steps need to be taken in order to help prevent breast cancer and improve treatment outcome. According to research, vitamin D could be part of the solution.

A Recent study has found a lower risk of breast cancer over five years of follow-up in association with higher levels of serum vitamin D or vitamin D supplementation. (1)

“The investigation included participants in a sister study, which enrolled women who had a sister diagnosed with breast cancer, which placed all these women at higher breast cancer risk.

The results; use of vitamin D supplement at least four times per week was associated with an 11% lower risk of the disease, in comparison to those who did not regularly supplement. Breast cancer risk was 17% lower among postmenopausal women who supplement with modest doses of vitamin D.” (2)

Although prevention is key, approximately one in eight women will develop breast cancer within their lifetime. The following study, and many before it, have supported a beneficial role of maintaining higher levels of vitamin D in women who already have breast cancer. Though this relationship has yet to be proven as causal, the many associations between breast cancer and vitamin D warrant public action.

“A total of 192 postmenopausal Brazilian women between the ages of 45 and 75 were included in this cross-sectional study. All of the participants attended the Breast Disease Assessment Center of the University Hospital in Southeastern Brazil during 2015-2016. The researchers collected the following data: age, menopausal age, time since menopause, age of first gestation, duration of breastfeeding, current smoking, prior use of hormone therapy, history of chronic diseases, family history of breast cancer and use of medications.

“They also measured the patient’s anthropometric data and serum vitamin D levels just following breast cancer diagnosis and prior to medical treatment. Due to the fact that breast cancer prognosis is widely variable, the researchers evaluated several markers that contribute to disease outcome including tumor grade, tumor stage, lymph node presence and hormone receptor status.(3)

 This is what the researchers found:

  • Average vitamin D status was 25.8 ng/ml (64.5 nmol/l).

  • Of the total participants, 33.9% were considered to be vitamin D sufficient (>30 ng/ml; >75 nmol/l), 47.9% were considered insufficient (20-30 ng/ml; 50-75 nmol/l) and 18.2% were considered vitamin D deficient (<20 ng/ml; 50 nmol/l)
  • Insufficient and deficient 25(OH)D levels were associated with increased tumor grade, locally advanced and metastatic disease, more positive lymph nodes, a lower proportion of ER, PR-positive tumors and higher Ki-67 indices. 
  • Vitamin D status was not significantly associated with tumor size, histology of breast cancer or HER2 status.” (3)

Due to lack of vitamin D within the diet, individuals looking to increase their vitamin D status should spend time outside when their shadow is shorter than they are tall or supplement with at least 5,000 IU daily (125 ug).



(1)Environ Health Perspect. 2017 Jul 6; 125(7)





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