Past studies have claimed that vitamin D may reduce the risk of heart disease, bone fractures and even depression, the Medical Daily News reported.
Now, new research suggests that breast cancer patients with high levels of the vitamin in their blood are twice as likely to survive the disease than patients with low levels.
The researchers, led by Prof. Cedric F. Garland of the University of California, San Diego School of Medicine, recently published their findings in the journal Anticancer Research.
Vitamin D ― a fat-soluble vitamin ― is important for regulating the absorption of calcium and phosphorus in our bones.
The body's main source of the vitamin is from the sun, but some foods ― such as oily fish, eggs and fortified fat spreads ― contain the vitamin in very small amounts. Supplements are also available to boost vitamin D intake.
Prof. Garland notes that his past studies revealed an association between low vitamin D levels and an increased risk of premenopausal breast cancer. From this, he decided to look at the link between 25-hydroxyvitamin D ― a metabolite that the body produces from vitamin D ingestion - and survival rates of breast cancer.
The research team conducted a statistical analysis of five studies that looked at the link between 25-hydroxyvitamin D and breast cancer.
The studies included a total of 4,443 patients with breast cancer and were performed between 1966 and 2010. All patients were followed for an average of 9 years.
Patients were divided into groups dependent on the levels of 25-hydroxyvitamin D in their blood. Women in the "high" group had an average of 30 nanograms per milliliter (ng/ml) of 25-hydroxyvitamin D in their blood, while women in the "low" group had an average of 17ng/ml in their blood.
The investigators note that the average blood level of 25-hydroxyvitamin D for breast cancer patients in the U.S. is 17 ng/ml.