Black and Latina women with low levels of vitamin D were more likely to develop breast cancer compared with those with sufficient levels.

Despite existing evidence suggesting that vitamin D may help to prevent breast cancer, few studies have considered the role of race/ethnicity in this link.

A new study published in the peer-reviewed journal Cancer collected data from women who self-identified as Black/African American and non-Black Hispanic. Katie O’Brien, PhD, of the National Institute of Environmental Health Sciences, and her colleagues gathered blood samples from 415 women (290 Black, 125 non-Black Hispanic) who later developed breast cancer as well as 1,447 women (1,010 Black, 437 Latina) who did not.

With an average follow-up of 9.2 years, researchers found that women with adequate levels of vitamin D had a 21% lower breast cancer rate than women with vitamin D deficiency (less than 20 nanograms/milliliter). The link was strongest among Latina women, who had a 48% lower rate, and weakest among Black women, who had an 11% lower rate.

These findings indicate that vitamin D may protect women against breast cancer, including those in racial/ethnic groups with low average levels of vitamin D.

The sun is one of the best sources of vitamin D (the skin absorbs the sun’s UVB radiation and converts it into vitamin D3), but it can also be found in tuna, shrimp, salmon, oysters, mushrooms, egg yolks, and fortified foods like cow’s milk, plant-based milk alternatives (soy, almond, hemp milk), orange juice and certain types of yogurt, according to Healthline.

“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 in a news release. “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.”

To learn more about the association between cancer and vitamin D, read “Vitamin D May Protect Against Young-Onset Colorectal Cancer.”