Antioxidant Synergy of the Glutathione Pathway and Incidence of Parkinson\u27s Disease: A Systematic Review

Background: The etiopathogenesis dopaminergic neuron dysfunction of Parkinson\u27s Disease (PD) has not been clearly established. Oxidative stress is a commonly proposed causative mechanism for this dysfunction as variations in antioxidant intake have been observed between older adults with and without PD. The objective of this systematic review was to evaluate the synergistic relationship between antioxidant micronutrients of the glutathione pathway and the incidence of PD in older adults. Methods: This systematic review evaluated the relationship between the intake of vitamins C, D, and E, and selenium, riboflavin and niacin and incidence of PD according to PRISMA guidelines. Four electronic databases (Medline (PubMed), CINAHL, Web of Sciences and SCOPUS) were reviewed, most recently on April 12, 2022. Risk of bias was assessed and reported for each study utilizing respective Joanna Briggs Institute (JBI) Quality Review Checklist for Case Control Studies and Cohort Studies, and Risk of Bias in Systematic Reviews (ROBIS) to assess systematic reviews and meta-analyses. Inclusion criteria were assessment of usual intake of above antioxidants, population of interest was idiopathic PD, and exclusion criteria were assessing population with mean age less than 50 years old, or deemed poor quality of evidence Results: A total of 31 studies were included in the final review after evaluating final inclusion/exclusion criteria. Vitamin D revealed the most prominent relationship with incidence of PD, with 18 of 19 studies identifying a negative relationship between intake and incidence, while results were largely inconclusive for vitamins E and C. There were no studies for selenium, riboflavin or niacin that met criteria for the current study