In the era of genetic research for neurodegenerative diseases, less attention has been paid to epidemiologists’ search for potential environmental risk factors for Parkinson disease (PD). Epidemiologic evidence suggests that cigarette smoking is associated with about 50% lower risk of PD¹ and exposure to certain pesticides such as rotenone and paraquat is associated with doubled risk.² Recent studies also suggest that higher concentration of serum urate, an endogenous antioxidant, is associated with a lower risk of PD.³ Compared with these observations, another epidemiologic finding has been largely neglected. Several prospective studies,^4–7 including the Honolulu-Asia Aging Study (HAAS),⁶ have reported that higher consumption of dairy products, or milk alone, was associated with higher risk for PD.