Vitamin D and breast cancer


17.12.2015. A new paper published in October 2015 in the American Journal of Clinical Nutrition suggests that vitamin D3 could oppose breast cancer caused by estrogen. The study of over 57,000 post menopausal women found that, among women who had ever used hormone therapy, those that were supplementing with vitamin D had a 26 % reduced risk of breast cancer (1).

All new research from different papers are showing that vitamin D has cellular effects that oppose the development of cancer by different mechanisms (promoting cell adhesion, inhibiting proliferation, and anti-inflammatory effects). Extensive research is done to clarify the relation of the vitamin to breast cancer where research is showing that higher blood levels of vitamin D is linked to reduced breast cancer risk.

What you need to know

We know that vitamin D has a protective effect on different types of cancer. Vitamin D can also oppose some effects of female hormones which is especially helpful for breast cancer prevention. In vitro experiments show that vitamin D inhibits the enzyme aromatase in breast cancer cells and thus less estrogen is produced. Also it downregulates estrogen receptors in breast cancer cells, making them less responsive. (2)

It is important that woman test their blood vitamin D levels. The test measures 25(OH) vitamin D which optimal level is from 30 to 45 ng/ml (3), and a little higher for cancer patients who’s optimal level ranges from 30 to 80 ng/ml (4).

The best and the most potent form to supplement is vitamin D3 (the same that is formed in skin during exposition to sunlight). Depending on the vitamin and health status, it is recommended to take 1000, 2000 or 4000 IU vitamin D3. These quantities seem to be enough to bring most people in the optimal range. Experience shows that taking 2000 IU can result in blood concentration 30-35 ng/ml, and 4000 IU result in over 50 ng/ml. Every person can show individual variation, and it is important to check 25(OH)D again by testing.


Do you need a quality vitamin D3 supplement?

I recommend this one Thorne Research: Vitamin D3 that can easily be dosed as needed.


1.Cadeau C, Fournier A, Mesrine S, et al. Interaction between current vitamin D supplementation and menopausal hormone therapy use on breast cancer risk: evidence from the E3N cohort. Am J Clin Nutr 2015, 102:966-973.
2.Krishnan AV, Swami S, Feldman D. The potential therapeutic benefits of vitamin D in the treatment of estrogen receptor positive breast cancer. Steroids 2012, 77:1107-1112.
3.Vitamin D, Hormones, and Breast Cancer. Dr Fuhrman web page, December 2015.
4.Mohr S.B., Gorham E.D., Kim J., Hofflich H., Garland C.F.: Meta-analysis of Vitamin D Sufficiency for Improving Survival of Patients with Breast Cancer. Anticancer Research, March 2014.


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