Serum vitamin D and the risk of Parkinson’s disease

CONTEXT: Low vitamin D status has been suggested to be related to Parkinson’s disease risk. OBJECTIVE: To investigate whether serum vitamin D level predicts the risk of Parkinson’s disease. DESIGN, SETTING AND PARTICIPANTS: The study was based on the Mini–Finland Health survey, which was conducted in 1978–1980, and followed-up for Parkinson’s disease occurrence through the end of 2007. The study population consisted of 3173 men and women, aged 50–79 years and free from Parkinson’s disease at baseline. During the 29–year follow–up period, 50 incident Parkinson’s disease cases occurred. Serum vitamin D (25(OH)D) was determined from frozen samples, stored at baseline. Estimates of the relationship between serum vitamin D concentration and Parkinson’s disease incidence were calculated using Cox’s model. MAIN OUTCOME MEASURE: Parkinson’s disease incidence RESULTS: Individuals with higher serum vitamin D concentrations showed a reduced risk of Parkinson’s disease. The relative risk between the highest and lowest quartiles was 0.33 (95% CI 0.14–0.80) after adjustment for sex, age, marital status, education, alcohol consumption, leisure-time physical activity, smoking, body mass index, and month of blood draw. CONCLUSIONS: The results are consistent with the suggestion that high vitamin D status provides protection against Parkinson’s disease. It cannot, however, be excluded that the finding is due to residual confounding and further studies are thus needed.