Prevalence and patterns of self-initiated nutritional supplementation in men at high risk of prostate cancer.

OBJECTIVE: To define the prevalence and patterns of self-initiated herbal and vitamin supplementation among men at high risk of developing prostate cancer, as there is increasing public awareness of prostate cancer screening, risk-factor assessment and prevention, leading to increasing interest in the use and systematic study of nutritional therapies for prostate cancer prevention. SUBJECTS AND METHODS: Since 1996 our institution has prospectively maintained a prostate cancer-risk registry through its Prostate Cancer Risk Assessment Program (PRAP). Eligibility includes African-American men, any man with at least one first-degree relative or two or more second-degree relatives with prostate cancer, or men who tested positively for the BRCA1 gene mutation. A 420-item self-administered questionnaire was completed and included the use of nutritional supplements and complementary therapies. We divided men into groups who used supplements to lessen their cancer risk and those who did not. The prevalence and patterns of use were evaluated and the two groups then compared for differences in demographic, socio-economic and risk-perception variables.
RESULTS: In all, 345 high-risk men were enrolled in the PRAP over a 5-year period. Data on the use of dietary or herbal supplements were available on 333 men (97%), of whom over half (170) reported taking one or more supplements to prevent prostate cancer. Supplement use was divided into eight categories, including vitamins, minerals, extracts from fruits/seeds, organic compounds, flowers/bulbs, leaves/bark, roots, or animal products. Most commonly used for self-initiated chemoprevention were vitamins (95%), minerals (28%), and fruit/seed extracts (18%). More than a quarter of men (27%) took three or more agents. Men taking proactive preventative measures were statistically more likely to be Caucasian and aged > 60 years (P < 0.05). African-Americans were less likely to self-initiate preventative steps. Men taking supplements tended to return more often for follow-up and participate in PRAP longer, while those not taking supplements tended to earn less and report less self-perceived risk.
CONCLUSIONS: A significant proportion of men at risk of developing prostate cancer initiate measures they perceive to reduce their risk. Although the chemopreventative efficacy of many of these supplements remains unsubstantiated, they are widely perceived by the public to reduce the risk of developing prostate cancer. These data provide an insight into patient perceptions and misconceptions of chemopreventative strategies, and may help to refine recruitment efforts in multi-institutional prostate cancer prevention trials.