One Major Effect of Taking Vitamin D Supplements, Says New Study

 Vitamin D has a host of health benefits, however, new research suggests that there's another reason you should at least consider taking a supplement.

According to a new study that was highlighted at the American Society of Clinical Oncology 2021 virtual annual meeting, having sufficient vitamin D levels is associated with an increased likelihood of surviving breast cancer.

Researchers measured vitamin D levels at the time of breast cancer diagnosis in nearly 4,000 people and then survival outcomes a decade later. 

"Our study shows that patients who had sufficient vitamin D levels at the time of diagnosis—blood concentration of at least 20 nanograms per milliliter—had a lower risk of death or cancer recurrence," Song Yao, PhD, a molecular epidemiologist and professor of oncology with the Department of Cancer Prevention and Control at Roswell Park Comprehensive Cancer Center, and one of the lead study authors told Eat This, Not That!

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Nicole Williams, MD, and breast medical oncologist with The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute adds the study revealed that women who had sufficient levels of vitamin D had 27% lower odds of dying of any cause during the 10-year follow up. They also had a 22% lower likelihood of death from breast cancer compared to women who were deficient in vitamin D.

While she says the findings of this study may serve as an opportunity to create an important intervention to improve breast cancer outcomes in women with the disease, "it is too early to broadly adopt vitamin D supplementation in our breast cancer patients as a way to improve survival."

She adds that additional research is needed to assess whether a change in vitamin D levels over time is associated with breast cancer prognosis, or the likely development of the disease. For context, the main assessment in this study was a one-time measurement of vitamin D levels at the time of diagnosis.

The study also revealed that Black women had the lowest vitamin D levels, which Williams says may partially explain why they're are at higher risk of poorer outcomes after a breast cancer diagnosis. An increased risk of death after a breast cancer diagnosis isn't the only major medical issue Black women face—many experts also point out this community of women is disproportionately affected by myriad health issues and disparities due to structural and systemic racism.

There are also a few limitations of this study.

"Our study is an observational study, which means that we cannot prove definitively that increasing vitamin D levels by supplementation after breast cancer diagnosis will improve patients' survival outlook," says Yao.

"Epidemiologic studies like this are an important step in understanding where we have opportunities to improve health, and we look forward to seeing the connections between vitamin D and cancer explored through further studies," he adds.