Paul Knekt, DPH; Annamari Kilkkinen, PhD; Harri Rissanen, MSc; Jukka Marniemi, PhD; Katri Sääksjärvi, MSc; Markku Heliövaara, PhD
Individuals with higher serum vitamin D concentrations showed a reduced risk of Parkinson disease. The relative risk between the highest and lowest quartiles was 0.33 (95% confidence interval, 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. The results are consistent with the suggestion that high vitamin D status provides protection against Parkinson disease. It cannot, however, be excluded that the finding is due to residual confounding and further studies are thus needed.