Seaweed consumption and the risk of prostate cancer: the Miyagi cohort study.

Some laboratory studies have shown that fucoidan, which is contained in seaweed extract, has inhibitory effects on the invasion and angiogenesis of tumor cells; however, the association between seaweed consumption and prostate cancer incidence remains unclear. The purpose of the present study was to examine the association between seaweed consumption and the risk of prostate cancer incidence in the Japanese population. Data from 19 311 men in the Miyagi Cohort Study who were 40-64 years old at baseline in 1990 were examined. Seaweed consumption was assessed at baseline using a self-administered food frequency questionnaire. The participants were divided into three categories based on seaweed consumption at baseline. During 24.5 years of follow-up, we identified 815 incident cases of prostate cancer. Multivariate analysis showed that seaweed consumption was not associated with prostate cancer incidence. The multivariate hazard ratios and 95% confidence intervals for prostate cancer incidence in the highest tertile versus the other tertiles were 0.76 (0.60-0.96) and 0.78 (0.61-0.99) ( P -trend = 0.15). Furthermore, the null association was independent of whether their clinical stage was localized or advanced. In this population-based prospective cohort study conducted in Japan, we found no significant association between seaweed consumption and the incidence of prostate cancer.