Long‐Term Intake of Folate, Vitamin B6, and Vitamin B12 and the Incidence of Parkinson's Disease in a Sample of U.S. Women and Men

Abstract Background Folate and vitamins B6 and B12 have been proposed as protective against the development of Parkinson's disease (PD). Two prior longitudinal studies were inconclusive. Objective The aim was to examine the association of long‐term intake of folate, vitamin B6, and vitamin B12 with the incidence of PD. Methods The study population comprised 80,965 women (Nurses' Health Study, 1984–2016) and 48,837 men (Health Professionals Follow‐up Study, 1986–2016) followed prospectively for the development of PD. Intake of B vitamins was measured at baseline and every 4 years thereafter using food frequency questionnaires. We estimated the hazard ratio (HR) and 95% confidence interval (CI) of PD based on quintiles of cumulative average intake adjusting for potential confounders. Secondary analyses considered different lagged exposure periods as well as baseline and recent intakes. Results In separate analyses of cumulative average intake, total folate, B6, and B12 were not associated with the risk of PD. Results from 8‐, 12‐, and 16‐year lag analyses were consistent with these findings. Results for baseline intake of folate and B6 also pointed toward a null association. In contrast, a lower PD risk was observed among individuals with higher baseline total intake of B12 (pooled HR top vs. bottom quintile: 0.80; 95% CI: 0.67–0.95; P ‐trend = 0.01); results from 20‐year lag analyses were consistent with this finding. Conclusions Our results do not support the hypothesis that a higher intake of folate or vitamin B6 would reduce PD risk in this population. Our results provide moderate support for a possible protective effect of vitamin B12 on the development of PD. © 2023 International Parkinson and Movement Disorder Society.