Vitamins, supplements, and prostate cancer-related risk

Many men use vitamins and other supplements to prevent the onset of prostate cancer or to prevent the progression of prostate cancer after diagnosis. However, a new article in Family Practice suggests that there is no really good clinical evidence for either of these practices in the published literature.

Stratton and Godwin have carried out a systematic review and meta-analysis of the available information on the preventive use of vitamin supplementation in relation to prostate cancer. After a careful search of PubMed, Embase and the Cochrane Database they were able to identify just 14 articles of sufficient quality to include in their meta-analysis, including randomized controlled trials (RCTs), cohort studies, and case-control studies. Their review assesses the effect of supplemental vitamins on risk of prostate cancer and on disease severity and death in men with prostate cancer.

According to Stratton and Godwin:

  • A few of these studies do show a relationship between the ingestion of supplemental vitamins or minerals and the incidence or severity of prostate cancer, especially in men with a history of smoking.
  • Neither the use of multivitamin supplements nor the use of individual vitamin/mineral supplements affects the overall occurrence of prostate cancer, the occurrence of advanced/metastatic prostate cancer, or death from prostate cancer when data from the 14 studies are combined in a meta-analysis.

It does have to be said that, despite the widespread use of all sorts of supplements in the prevention and management of prostate cancer, there really is very little good evidence that such products have a clinical effect on the onset or progression of prostate cancer. Even the recent data on the potential of pomegranate extract from a second Phase II trial can be questioned on a statistical basis because of the study design.

The “New” Prostate Cancer InfoLink thinks that careful use of vitamin supplements can often be justified if there is good evidence for effects on other aspects of health (certainly true for the use of vitamin D) or if there is good evidence that the risk associated with use of these products is minimal (apparently true for the use of pomegranate juice and extracts). We also encourage patients to discuss the use of any and all supplements with their doctors to ensure that use of such supplements is not likely to affect or complicate other forms of treatment. Some vitamins and supplements do most certainly induce “drug-supplement” interactions.

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