Low Vitamin D Might Be Linked to Prostate Cancer
Adequate levels may help keep cell growth in check, but researchers say more study needed
To test that idea, researchers checked vitamin D levels in 667 Chicago men between the ages of 40 and 79 who were having prostate biopsies because they'd recently had an abnormal prostate specific antigen (PSA) test or because a doctor felt changes to the prostate during a physical exam.
Normal vitamin D levels are in the range of 30 to 80 nanograms per milliliter (ng/ml).
Vitamin D deficiency, or a level under 20 ng/ml, was relatively common among all the men tested.
About 44 percent of the men with positive biopsies and 38 percent of those who tested negative for cancer had low vitamin D levels.
Among men who tested positive for cancer after their biopsies, those who also had very low levels of vitamin D -- under 12 ng/ml -- had greater odds of more advanced and aggressive cancers than those with normal levels.
The connection between vitamin D and cancer seemed to be even stronger in black men.
Black men with vitamin D levels under 12 ng/ml were far more likely than those with normal levels to test positive for prostate cancer in the first place.
In general, black men are also more likely to be diagnosed with prostate cancer. On average, men have about a one-in-seven lifetime risk of getting prostate cancer. That risk rises to one in five for black men, according to the U.S. Centers for Disease Control and Prevention.
Researchers aren't sure whether lower vitamin D levels may help to explain why black men are at higher risk for prostate cancer.
They say longer and larger studies are needed to sort out the connection.