A recent study published in Clinical Cancer Research, (May 1, 2014; 20; 2289-99) indicated that men at risk of prostate cancer are more likely to develop an aggressive form of the disease if they are deficient in vitamin D. University of Illinois – Chicago and Northwestern University researchers examined data from 667 men aged 40 to 79 who had elevated PSA levels or other prostate cancer risks. The men were screened for vitamin D levels. In general, normal blood levels of 25-hydroxyvitamin D range from 30-80 ng/mL. Typical values for men in the study were under 20 ng/mL. About 44% of men with positive biopsies had low vitamin D levels. Among the men who had a positive cancer biopsy, those with very low vitamin D levels (under 12 ng/mL) had greater odds of more advanced and aggressive cancers than those with normal levels. The lower the vitamin D level, the greater the risk. It should be noted that while 25-hydroxyvitamin D is known to impact growth of both benign and malignant prostate cells, this is the first study to link vitamin D deficiency and biopsy outcomes in high-risk men. The authors note that “vitamin D deficiency could be a biomarker of advanced prostate tumor progression in large segments of the general population”, however, more research is needed. But it would be wise for men to be screened for vitamin D deficiency using the 25-hydroxyvitamin blood test and treated if needed.