Researchers at the University of South Carolina studied 107 women who had been diagnosed with breast cancer in the past five years, including 60 African-Americans. Sixty percent of African-American women studied had low vitamin D levels, compared to 15% of white women.
“We know that darker skin pigmentation acts somewhat as a block to producing vitamin D when exposed to sunlight, which is the primary source of vitamin D in most people,” study author Susan Steck, PhD, MPH, professor of epidemiology at the University of South Carolina, says in a news release.
All participants donated a blood sample, and vitamin D concentrations were measured.
The mean serum concentration of vitamin D was 29.8 nanograms per milliliter (ng/mL) in white women and 19.3 ng/ml in African-American women, researchers say in a news release.
Vitamin D deficiency was defined as serum concentration of less than 20 ng/mL. Aggressive breast cancer was eight times more likely among patients with vitamin D deficiency.
More Research Needed on Effects of Vitamin D Deficiency
The study, Steck says, provides a foundation for possible preventive strategies, but she adds that more research is needed to confirm findings.
All participants were between 33 and 84 years old.
The study “corroborates other research showing racial differences in vitamin D status and provides further support for a protective role of vitamin D in breast cancer,” Steck says in an abstract of the study, presented in Miami at the Third American Association for Cancer Research Conference on the Science of Cancer Health Disparities. “The prevalence of vitamin D deficiency and insufficiency was high, suggesting the need for monitoring of vitamin D levels among breastcancer patients.”
Vitamin D levels are affected by sun exposure, dietary intake, supplements, skin tone, age, and body mass index.
This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.