Researchers say the results suggest that getting a daily dose of the vitamin from milk, the sun, and a multivitamin may also help reduce invasion and spread of the deadly disease. The American Cancer Society estimates that there will be more than 230,000 new cases in American men this year.
But researchers warn against taking large amounts of vitamin D without medical supervision. The vitamin D used in the study (1alpha,25-hydroxyvitamin D3) is the most potent and active form of vitamin D in the human body.
"This high dose has some side effects, including increasing blood calcium levels and causing kidney problems," says Edward M. Messing, MD, chair of urology at University of Rochester Medical Center, where the study was conducted, in a news release. "It should not be taken without prescription and a physician monitoring the side effects."
Vitamin D May Help Treatment
In the study, published in Carcinogenesis, researchers examined the effects of high doses of vitamin D that worked against the "invasive ability" of prostate cancer cells tested in a laboratory.
Their results showed that vitamin D limited the activity of two enzymes involved in prostate cancer spread.
Researchers say the findings indicate adding vitamin D to standard prostate cancer treatment may help men with advanced prostate cancer.
"We wanted to know the targets of vitamin D so we would know which patients would respond better," says researcher Yi-Fen Lee, PhD, assistant professor of urology at the University of Rochester Medical Center, in the release.
Lee says other medicines or vitamins may also help enhance the anticancer effects of vitamin D. But until further research confirms these findings, he says, "the best way to get vitamin D is to drink milk, get modest exposure to the sun, and take a vitamin pill to enrich the vitamin D, which might prevent cancer."