The authors examined whether a diet that increases plasma urate level is also related to reduced risk of Parkinson's disease (PD). The study population comprised 47,406 men in the Health Professionals Follow-up Study. The potential effect of diet on plasma urate level was estimated by regressing plasma urate on intakes of selected foods and nutrients in a subsample of 1,387 men. Coefficients of this regression model were then used to calculate a dietary urate index for all cohort participants. Multivariate relative risks of PD were estimated by means of Cox proportional hazards models. After 14 years of follow-up (1986-2000), the authors documented 248 incident cases of PD. A higher dietary urate index was associated with a lower risk of PD (top quintile vs. bottom: relative risk = 0.47, p-trend = 0.0008), after adjustment for age, smoking, caffeine intake, and other potential confounders. This association remained strong and significant after further adjustment for each component of the index individually (p-trend < 0.02 for each). These data support urate as a potentially protective factor in PD and suggest that dietary changes expected to increase plasma urate level may contribute to lower risk of PD. These potential benefits, however, should be weighed against expected adverse effects on risk of gout and other chronic diseases.