Study explain why vitamin D protects against prostate cancer

A study released in the Jul-Aug 2006 issue of Anticancer Research suggests that taking high doses of vitamin D supplements may inhibit growth of prostate cancer.

J. Moreno and colleagues of Stanford University School of Medicine reported that calcitriol or 1,25-dihydroxyvitamin D3, the active form of vitamin D inhibits growth of prostate cancer cells.

The researchers conducted a cDNA microarray analysis and found vitamin D acts on a number of genes that play important roles in the metabolism of prostaglandins (PGs), which are known to stimulate the growth and progression of prostate cancer.

One gene suppressed by vitamin D is the cyclooxygenase-2 or cox-2 gene that is involved in synthesizing PGs and another affected gene is 15-prostaglandin dehydrogenase or 15-PGDH, which deactivates the prostaglandin.

The researchers also found calcitriol suppresses the expression of the prostaglandin receptors EP2 and FP, reduces the biological activity of PGs and inhibits the action of PGs in prostate cancer cells.

Moreno et al. proposed that "calcitriol can be combined with non-steroidal anti-inflammatory drugs (NSAIDs) that inhibit COX enzyme activity, as a potential therapeutic strategy in pCa (prostate cancer).

High serum levels of vitamin D have been associated with lower risk of prostate cancer and many other types of malignancies, suggesting that vitamin D may protect against cancer.

Calcitriol is highly potent and may be available as a prescription drug.  Healthy people may use high doses of vitamin D or cholecalciferol, which is available as a dietary supplement.

A recent study led by Cedric Garland and Robert P. Heaney, two veteran vitamin D experts, suggests people need 4000 to 8000 IUs of vitamin D daily to prevent cancer.

Prostate cancer is diagnosed in about 200,000 men in the United States each year and the disease and its complications kills about 35,000 annually.

David Liu