Vitamin D may reduce the risk of breast cancer, according to a number of observational studies. But little has been known about how race and ethnicity affect this association. So researchers at the National Institute of Environmental Health Sciences looked to see whether vitamin D levels were related to breast cancer risk in a group of Black/African American and Hispanic/Latina women.
Black and Latina women who had sufficient levels of vitamin D had a reduced risk of breast cancer, they found.
The finding suggests interventions promoting vitamin D intake may benefit women of color, particularly because they tend to have lower average vitamin D levels than non-Hispanic white women, Katie O’Brien, lead author of the study, told TheDoctor.
People with darker skin produce less vitamin D than those with lighter skin.
The women were enrolled in an ongoing Sister Study of over 50,000 women in the U.S. who had a sister diagnosed with breast cancer, although they had never received a breast cancer diagnosis themselves.
Almost 300 Black/African American women and 125 Hispanic/Latina women in the study developed breast cancer, while 1,010 Black/African American women and 437 Hispanic/Latina women did not.
Hispanic/Latina women had a 48 percent lower risk of breast cancer if they had sufficient vitamin D levels.
Those participants with sufficient vitamin D levels (>20 ng/mL) had a 21 percent lower risk of breast cancer than did women who had a vitamin D deficiency (<20 ng/mL) over a nine-year follow-up period, This relationship was strongest among Hispanic/Latina women, who had a 48 percent lower risk of breast cancer if they had sufficient vitamin D levels. Black/African American women with sufficient vitamin D had an 11 percent lower breast cancer risk.
To get a better understanding of the effects of vitamin D, the team will look at how race and ethnicity, vitamin D levels and breast cancer risk intersect with factors like nutrition, exercise and exposure to environmental toxins. O’Brien added, “We have plans to follow up this work with studies that consider the genetic and epigenetic factors involved.”
The study is published in Cancer.