Low Dietary Vitamin C Intake Is Associated with Pro-Inflammatory Taxa and Oxidative Stress Related Functional Pathways in Parkinson’s Disease with No Correlation to Age of Onset

Abstract

Vitamin C, a dietary antioxidant, has been extensively studied for its neuroprotective role in the development of Parkinson’s disease (PD). PD and antioxidants have also been found to exhibit contrasting influences on gut microbiome composition. Despite this, there is limited research investigating the potential role of the gut microbiome as a mediator between dietary vitamin C intake and PD age of onset. To address this gap, we examined the association between dietary vitamin C intake, gut microbiome composition, and PD age of onset using 16S rRNA sequencing data from Cirstea et al. The gut microbiome composition of PD patients (n = 197) was analyzed in relation to vitamin C intake levels, but no significant differences in gut microbiome diversity (alpha and beta) were found. Four microbial genera were identified as distinct gut microbial signatures linked with vitamin C intake (indicator taxa & differential abundance analysis). Namely, lower intake correlated with pro-inflammatory Escherichia-Shigella (P = 0.048, Stat = 0.714), and high intake with three taxa: Victivallis (P = 0.008, Stat = 0.568), an unclassified genus belonging to the Muribaculaceae family (P = 0.005, Stat = 0.573), and UCG-005 of the Oscillospiraceae family (P adjusted = 0.040, ANCOMBC2). Predicted functional analysis displayed an association between high vitamin C intake and the underrepresentation of 15 metabolic pathways related to vitamin C metabolism and oxidative stress (P < 0.05, LinDA). This distinct metabolic profile suggests that high vitamin C intake may regulate oxidative stress by modulating the gut microbiome, potentially influencing PD progression. Nevertheless, taxa associated with vitamin C intake levels showed no predictive power for PD age of onset (adjusted R² = 0.068). Overall, our findings highlight dietary vitamin C’s association with shifts in the PD microbiota composition and functional potential. Yet, this variation does not appear to be reflected in the age of onset. Therefore, while vitamin C intake may be associated with microbiome differences, our findings do not support vitamin C alone as a key factor in PD prevention.