Study finds link between vitamin D and breast cancer risk

Much has been written lately about vitamin D, that golden ray of supplement that — if you don’t have enough in your bloodstream — can cause a host of issues, from cardiovascular disease to aggression in children.

A new case study now suggests women who identified as Black/African American or Hispanic/Latina and were vitamin D deficient were more likely to develop breast cancer than those with adequate levels. The link was especially evident among Hispanic/Latina women.

For their research, Katie O’Brien, Ph.D., 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. All of the women were participating in the nationwide Sister Study cohort.

According to the researchers, Black/African American or Hispanic/Latina women have lower average vitamin D levels than non-Hispanic white women. Studies have suggested vitamin D might protect against breast cancer, but few studies have considered the role of race/ethnicity in this link.

The results of the case study showed that, over an average follow-up period of 9.2 years, women with sufficient vitamin D levels had a 21% lower breast cancer rate than those who were deficient. 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 their levels were sufficient.

“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,” O’Brien said. “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.”

The study was published by Wiley online in Cancer, a peer-reviewed journal of the American Cancer Society.

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