LOS ANGELES: Higher levels of vitamin D may lower the risk of developing breast cancer, a study has found.
Researchers from the University of California in the US pooled data from two clinical trials with 3,325 combined participants and a prospective study involving 1,713 participants to examine the association between risk of female breast cancer and a broad range of serum 25-hydroxyvitamin D (25(OH)D) concentrations, which was chosen as the marker because it is the main form of vitamin D in blood.
All women participants were 55 or older and the average age was 63. The data were collected between 2002 and 2017.
The participants were free of cancer at enrollment and their Vitamin D levels were measured during study visits for a period of four years.
Over the course of the combined studies, 77 new cases of breast cancer were diagnosed for an age-adjusted incidence rate of 512 cases per 100,000 person-years.
Researchers identified the minimum healthy level of 25(OH)D in blood plasma to be 60 nanograms per millilitre (ng/ml), substantially higher than the 20 ng/ml recommended in 2010 by the National Academy of Medicine, a US health advisory group.
"We found that participants with blood levels of 25(OH)D that were above 60 ng/ml had one-fifth the risk of breast cancer compared to those with less than 20 ng/ml," said Cedric F Garland, a professor at the UC San Diego.
Risk of cancer appeared to decline with greater levels of serum vitamin D.
Garland, who has previously studied connections between serum vitamin D levels and several types of cancer, said the study builds upon previous research linking vitamin D deficiency to a higher risk of breast cancer.
The study is not conclusive as it studied only postmenopausal breast cancer.
Further research is needed on whether high 25(OH)D levels might prevent premenopausal breast cancer," Garland said.