TUCSON, ARIZONA. A study based on a group of women from Saudi Arabia, mean age 48 years, recently reported in The American Journal of Clinical Nutrition. This case control study population was drawn from patients admitted to hospital between June and August 2009. Breast cancer cases had significantly lower levels of 25-hydroxyvitamin D (25(OH)D than controls (9.4 vs. 15.4 ng/mL). In comparison with those in the highest vitamin category (= 20 ng/mL), women with 25(OH)D levels < 10 had a 6-fold increase in incidence and those between 10 and 20 ng/mL had a 4-fold increase. A level of 20 ng/mL is still not sufficient and the low levels even for a group recruited in the summer presumably reflects the darker skin type and the likelihood of reduced exposure to UV radiation associated with cultural dress practices and an indoor lifestyle.

These results are consistent with numerous studies supporting the view that women need vitamin D levels exceeding 20 ng/mL, a recommendation still seen. In fact, a study published in July 2009 in Annals of Epidemiology found that raising 25(OH)D levels to 40-60 ng/mL would prevent 58,000 new cases of breast cancer and three-quarters of deaths from this disease in the US and Canada. Achieving these levels with supplementation is simple and inexpensive, and emphasizes that everyone should know their 25(OH)D number.

Yousef FM, Jacobs ET, Kang PT et al. Vitamin D status and breast cancer in Saudi Arabian women: case-control study. Am J Clin Nutr 2013 July;98(1):105-10