Study: Vitamin D May Have a Role in Breast Cancer Rates Amongst Black, Hispanic Women

Vitamin D may have a role in breast cancer prevention, particularly amongst Black and Hispanic/Latina women, according to a new study. 

Released by the Sister Study, an ongoing nationwide study conducted by the National Institute of Environmental Health Sciences, the study found that the Black and Hispanic/Latina women participating in the study with enough vitamin D had lower rates of breast cancer development compared to those that had a vitamin D deficiency, especially amongst the Hispanic/Latina participants. 

On average, the women that had normal levels of vitamin D had a 21% lower breast cancer rate. The rate was higher amongst the Hispanic/Latina participants who had a 48% lower breast cancer rate than the Black participants who had an 11% lower breast cancer rate.

“Black women and Latinas have lower vitamin D concentrations, on average, than non-Hispanic White women,” said lead researcher Dr. Katie O’Brien Ph.D. “Therefore, if higher vitamin D levels are associated with lower risk of breast cancer, women in these racial/ethnic groups may derive greater benefit from interventions to increase vitamin D levels.”

To conduct the study, researchers, including Dr. O’Brien, gathered blood samples from 415 women, 290 of whom identified as Black and 125 of whom identified as Hispanic/Latina, that went on to get a breast cancer diagnosis. 

Also taking blood samples from 1,545 women, 1,084 who identified as Black and 461 who identified as Hispanic/Latina, who didn’t develop breast cancer, the blood samples of all these women were taken to measure vitamin D levels. Initially drawn when they first enrolled in the program between 2003 and 2009, the women were all cancer-free at this point of the study.

The researchers followed the participants through September 2018 and analyzed the blood samples in 2020 to determine if there’s a connection, comparing the different types of vitamin D levels of the women who developed breast cancer to the women who didn’t. 

While the results did show a connection, Dr. O’Brien still warns people that more research needs to be conducted before increasing the recommended dosage of vitamin D. 

“Yes, we did observe that vitamin D concentrations were inversely associated with breast cancer incidence. This supports the hypothesis that interventions to increase individuals’ vitamin D concentrations could possibly decrease their breast cancer risk,” said Dr.O’Brien. “However, an observational study like this cannot assess whether the relationship is truly causal. 

“In other words, we can’t rule out that there might be other factors that we didn’t account for in our statistical models that explain the association we observed,“ she added. 

In their next steps, Dr. O’Brien and the other researchers at the Sister Study plan to look further into the connection by studying the genetic and epigenetic factors involved that might have an effect.