Vitamin D Review

[August 4, 2011]

A review paper by Barnett and Beer that appeared in Urol Clin North Am. 2011 Aug;38(3):333-42 discusses the current status of Vitamin D research. [PMID: 21798396]. According to that paper it seems clear that vitamin D is involved in prostate cancer biology and that there is an anticancer effect in animals but it is much less clear whether there is a significant beneficial effect of vitamin D supplementation in humans. Below we outline the main points:

• geographic areas of low UV exposure have increased risk of prostate cancer
  
• in test tube and animal studies vitamin D has shown an anti-cancer effect
  
• because calcium tends to depress vitamin D it would be expected that if vitamin D were anti-cancer in humans then low calcium intake would correlate with lower risk of prostate cancer but of 12 recent studies 8 showed no relationship with calcium
  
• out of 13 studies 9 showed no association between low vitamin D and increased risk of prostate cancer
  
• some caveats are that the following may (or may not) be (a) it might be that the studies just cited did not have sufficient numbers of patients to detect a difference, (b) it might be that the effect of low vitamin D is to increase the risk of aggressive prostate cancer rather than increase the risk of prostate cancer
  
• studies relating genetic variations in Vitamin D genes and prostate cancer progression have been inconclusive
  
• multiple studies with calcitriol + chemo have resulted in lower PSA levels; however, a phase III trial was halted due to deaths in the treatment arm
  
• it may be that vitamin D therapy only works in certain targeted subgroups
  

In conclusion:

"At present, there are no consistent data to support high dose vitamin D supplementation for the average patient with prostate cancer for the treatment or halting of cancer progression. In addition, there are no data to support therapeutic use of vitamin D and its analogs in treating prostate cancer. Additional studies are needed to determine if higher doses of vitamin D supplements could benefit selected populations (ie, the elderly or patients with cancer) even if they may not be beneficial for the general population."

and for the average prostate cancer patient

"a recommended minimum of 600 IU of vitamin D per day, with testing at baseline to determine if additional supplementation is needed for deficiency levels (< 20 ng/mL) is reasonable."