I told you so! A new study shows that vitamin D is critically important to prevent breast cancer.

There was an uproar recently about a study indicating that vitamin D supplementation had no affect on breast cancer risk.[1] The press picked it up and regurgitated it ad nauseam as if were the end-all-be all of scientific studies. I told you then that it was bad research because it used a miniscule quantity of vitamin D—400 IU per day—rather like trying to attack an elephant with a bb gun. In fact, a 400 IU daily supplementation for seven weeks has been shown to lead to reduced vitamin D levels in winter, whereas tanning bed exposure raises vitamin levels by 150% in the same time period.[2] It should be no surprise that a vitamin D supplement that is so tiny that it leads to deficiency would not help women to prevent breast cancer.

Now we have a new study from Germany showing that women with the highest vitamin D levels have a 55% reduced risk of breast cancer compared to those with the lowest levels.[3] Another study showed that three years of supplementation with calcium and vitamin D correlated to a reduced risk of all cancers in women by up to 77%.[4] However, the supplementation was 1,100 IU per day, not 400.

What can I say? I told you so.


[1] Chlebowski R, et al. Calcium Plus Vitamin D Supplementation and the Risk of Breast Cancer. JNCI Published online 11-11- 2008.
[2] Holick, M. et al. Boston University. "Effects Of Vitamin D And Skin's Physiology Examined." Science Daily 21 February 2008 .
[3] Abbas, S. et al. Plasma 25-hydroxyvitamin D and premenopausal breast cancer risk in a German case-control study. Int J Cancer 2009;124:250-5.
[4] Lappe, J. et al. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J Clin Nutr 2007;85:1586–91.