Researchers say previous studies in the lab have suggested that high doses of vitamin D may cut prostate cancer risk. But statistical studies that looked for specifically what causes prostate cancer and whether vitamin D is helpful have been inconclusive, they say.
In this study, researchers from the National Cancer Institute compared 749 men who had been diagnosed with prostate cancer to a control group of 781 men who didn't have the disease but who were similarly matched up in terms of age and other factors.
The study was conducted alongside a cancer screening trial.
The researchers found no "statistically significant" difference when it came to whether higher blood levels of vitamin D reduced the risk of developing prostate cancer.
Researchers did find a slight trend that the disease was more aggressive with higher concentrations of vitamin D in the blood. Study authors urge more research on that front.
In an editorial that accompanies the study results, researchers say that vitamin D deficiency is emerging as a "public health concern."
Vitamin D is produced by the body when the skin is exposed to sunlight. However, people with darker skin and the elderly may not produce enough. Other sources of vitamin D include certain foods, especially foods fortified with vitamin D, such as milk and cereals.
The study was carried out by Jiyoun Ahn, PhD, and Richard Hayes, DDS, PhD, of the National Cancer Institute.
By Kelley Colihan
Reviewed by Louise Chang
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