Low levels of vitamin D among Black, Hispanic women associated with higher breast cancer risk

Among women who identified as Black/African American or Hispanic/Latina, those with low blood levels of vitamin D were more likely to develop breast cancer than those with adequate levels. In the study published by Wiley online in CANCER, a peer-reviewed journal of the American Cancer Society, the link between low vitamin D and breast cancer was particularly evident among Hispanic/Latina women.

Black/African American or Hispanic/Latina have lower average vitamin D levels than non-Hispanic white women. Although research suggests that vitamin D may protect against breast cancer, few studies have considered the role of race/ethnicity in this link.

To investigate, Katie O'Brien, PhD, of the National Institute of Environmental Health Sciences, and her colleagues collected blood samples from 415 women (290 Black/African American, 125 non-Black Hispanic/Latina) who later developed breast cancer, as well as from 1,447 women (1,010 Black/African American, 437 Hispanic/Latina) who did not develop breast cancer.

Over an average follow-up of 9.2 years, women with sufficient vitamin D levels had a 21% lower breast cancer rate than women with vitamin D deficiency (<20 ng/mL). The link was strongest among Hispanic/Latina women, who had a 48% lower rate if they had sufficient vitamin D levels. The link was weaker among Black/African American women, who had an 11% lower rate if they had sufficient vitamin D.

Together with prior studies on this topic, this article suggests that vitamin D may be associated with reduced risk of breast cancer, including among women who self-identify as Black, African-American, Hispanic, or Latina. Because women who identify as members of these groups have lower vitamin D levels, on average, than non-Hispanic white women, they could potentially receive enhanced health benefits from interventions promoting vitamin D intake. However, questions remain about whether these associations are truly causal and, if so, what levels of vitamin D are most beneficial."

Dr. Katie O'Brien, PhD, National Institute of Environmental Health Sciences