Vitamin D concentrations of 60 ng/mL or higher in blood plasma significantly reduced the risk for breast cancer among postmenopausal women, according to a study published in PLoS One.
“Breast cancer is the most common non-skin cancer in women,” Sharon L. McDonnell, MPH, from GrassrootsHealth, and colleagues wrote. “More than 252,000 new cases of female breast cancer and 40,600 deaths were projected to occur in 2017 in the United States. While more early detection and improvements in treatment have reduced the mortality rate, there has been no reduction in the incidence of breast cancer in the past 20 years. Identifying and implementing effective primary prevention strategies could reduce breast cancer incidence rates.”
McDonnell and colleagues pooled data from two randomized clinical trials and a prospective cohort to examine the association between a broad range of serum 25-hydroxyvitamin D concentration and breast cancer risk among women aged 55 years and older (n = 5,038; average age, 63 years).
Participants did not have cancer at enrollment and were followed for a mean of 4 years. The researchers measured participants’ vitamin D levels in blood at baseline, then each year afterwards. They defined the minimum healthy level of 25-hydroxyvitamin D in blood as 60 ng/mL and noted that this benchmark is significantly higher than the 2010 National Academy of Medicine’s recommendation of 20 ng/mL.
Overall, 77 women were diagnosed with breast cancer over the course of the study.
Women with vitamin D levels of 60 ng/mL or more demonstrated an 82% lower risk for breast cancer, compared with those with vitamin D levels lower than 20 ng/mL (RR = 0.18). After adjusting for age, BMI, smoking status and calcium supplement intake, the risk for breast cancer was 80% lower among women with vitamin D levels of 60 ng/mL or more vs. those with vitamin D levels lower than 20 ng/mL (HR = 0.2).
There was a consistent decrease in the risk of breast cancer as vitamin D levels increased. More women with vitamin D levels of 60 ng/mL or more were breast cancer-free than those with vitamin D levels lower than 20 ng/mL (99.3% vs. 96.8%).
“This study provides strong support that vitamin D plays an important role in breast cancer prevention,” Joan M. Lappe, PhD, RN, co-author from Creighton University, said in a press release. “It also demonstrates that blood levels of vitamin D for breast cancer prevention need to be higher than currently recommended levels for bone health.”
Since this study was limited to postmenopausal breast cancer, more research is required to uncover the role of vitamin D in preventing premenopausal breast cancer, Cedric F. Garland, DrPH, coauthor from the University of California, San Diego, said in a press release.
“With roughly an 80% reduction in the incidence of breast cancer, getting a vitamin D blood level to 60 nanograms per milliliter becomes the first priority for cancer prevention,” Carole Baggerly, BA, co-author and director of GrassrootsHealth, said in a press release. “Nutrition and lifestyle factors are certainly important for overall health, but they can’t replace the value of vitamin D level. The safety of this level has been demonstrated within this study as well as others.” – by Alaina Tedesco
The authors report no relevant financial disclosures.