ScienceBased Health joins experts in criticizing "Multivitamin Use / Prostate Cancer Risk" Study

Regular Multi-vitamin Use Not Linked to Overall Risk of Prostate Cancer
Use of multivitamin supplements was found to be unrelated to overall risk of prostate cancer in a large prospective study published in the May 16 2007 Journal of the National Cancer Institute (1). The study's authors did report, however, that a sub-group of men who used multi-vitamin and mineral supplements excessively (defined as more than 7 times a week) had an increased risk of advanced and fatal prostate cancer compared to men who never used multi-vitamins. (It is important to note that the survey used in this study asked if subjects used multivitamins from "never" up to "every day". Thus, it is unclear how the researchers derived a value for "more than 7 times per week", which was not an option on the survey).

Limitations of the Study
Many experts agree that the findings are not necessarily applicable to the general public because of significant limitations in the study's research design. A key limitation was the inability to collect or analyze the amounts of the many different nutrients that were supplemented, or how long they were taken. Men using multivitamins "excessively" were also more likely to take a variety of individual supplements, making it impossible to identify or quantify any individual nutrients within the "multis" that could have been responsible for the observed association.

Most importantly, it's well recognized that men at high risk for advanced prostate cancer or diagnosed with the disease, tend to use more alternative therapies including supplements. That increased use is a likely explanation for the apparent link between excessive use and increased risk for fatal or advanced cancer since this association disappeared when the investigators controlled for this factor in their analysis.

AREDS Findings Are Reassuring
The authors of this study also found that the positive association with "excessive" multivitamin use and advanced or fatal prostate cancer was strongest in men with a family history of the disease, or among men who took additional individual supplements including beta-carotene and zinc. In contrast, a follow-up analysis of the Age-Related Eye Disease Study (AREDS) found that AREDS participants taking zinc alone or with antioxidants were 14% less likely to die after 6.5 years of supplementation compared to those taking a placebo (2). No increased deaths from cancer in those taking zinc (alone or with anti-oxidants) was noted in this analysis. However, to err on the side of safety, men with elevated PSA levels or diagnosed with prostate cancer should discuss the issue with their own physician to determine the best course of action.

• Don't use daily multivitamins excessively. Use them as directed. The idea that "if a little is good, more is better" is not always the best recipe for good health.
  
• As a general rule, don't combine many individual nutrient supplements instead of a taking a multi - or even in addition to a multi - unless advised to do so by a qualified health professional. Each individual nutrient has its own unique safety range, and taking many nutrients singly, or in addition to a multi, could result in exceeding those safety ranges.
• Choose multis that are formulated by nutrition scientists and ocular experts to ensure that supplements contain the highest quality ingredients, are balanced and scientifically sound.

1. Lawson KA et al. Multivitamin use and risk of prostate cancer in the National Institutes of Health-AARP diet and health study. J Natl Cancer Inst 99:754-64, 2007.
2. AREDS report No. 13, AREDS Research Group. Association of mortality with ocular disorders and high dose antioxidants and zinc in the Age-related Eye Disease Study. Arch Ophthalmol 122:716-726, 2004.