CAT and Parkinson disease: Figure 2 presents the forest plots of the associations between Zn and PD. The IVW method shows that genetically determined Zn was strongly associated with PD (OR = 1.107, 95% CI 1.013–1.211; p = 0.025), which is consistent with results from the WM method (OR = 1.136, 95% CI 1.003–1.286; p = 0.044) (Table 2; Figure 2). However, there were no significant associations of catalase, glutathione peroxidases, superoxide dismutase, vitamin A, vitamin C, vitamin E, vitamin B12, folate, copper, or iron with PD (Table 2).