Intake of Folate, Vitamin B6, and Vitamin B12 Before and After Disease Diagnosis and the Risk of Death in Individuals with Parkinson's Disease.

backgroundObjective The aim of this study was to examine whether the intake of folate, vitamin B6, and vitamin B12 before and after disease diagnosis impacts the risk of death among individuals with Parkinson's disease (PD). The impact of folate, vitamin B6, and B12 intake on mortality in individuals with PD is unknown. Methods The study population comprised 1521 participants of two large prospective cohorts who were newly diagnosed with PD during follow-up. Participants responded to repeated dietary assessments using validated food frequency questionnaires, covering up to 30 years before to more than 10 years after PD diagnosis. We estimated the hazard ratio (HR) and 95% confidence interval (CI) of death according to quartiles of the cumulative average intake of B vitamins before and after disease diagnosis. We also examined PD-specific mortality and alternative exposure definitions. Results We documented 1005 deaths during 15 years of follow-up. A higher cumulative average intake of B vitamins before disease diagnosis was associated with a lower risk of death among patients with PD. The multivariable-adjusted HR (95% CI) of death comparing top to bottom quartiles of intakes was 0.78 (0.62-0.99) for folate, 0.76 (0.62-0.93) for B6, and 0.86 (0.69-1.09) for B12. These estimates were stronger in analyses restricting to intakes from supplemental sources and in those considering intakes reported up to 12 years before diagnosis. The intake of these B vitamins after PD diagnosis was not associated with the risk of death. Conclusions Higher intake of B vitamins before disease diagnosis, particularly folate and vitamin B6, may decrease the risk of death in individuals with PD. Postdiagnosis intake did not appear to impact survival.