This study investigates the association between diet and gut microbiome composition in patients with Parkinson's disease (PD). Using 16S rRNA gene sequencing, the researchers assessed the gut microbiota in fecal samples from 85 PD patients in central California. Diet quality was evaluated using the Healthy Eating Index 2015 (HEI-2015), and the impact of diet on microbial diversity, composition, taxon abundance, and predicted metagenomic profiles was examined. Higher HEI scores and fiber intake were associated with an increase in anti-inflammatory butyrate-producing bacteria, such as *Butyricicoccus* and *Coprococcus* 1, while higher added sugar intake was linked to an increase in pro-inflammatory bacteria, such as *Klebsiella*. Predictive metagenomics revealed that bacterial genes involved in lipopolysaccharide biosynthesis decreased with higher HEI scores, and genes involved in taurine degradation decreased, indicating reduced neuroinflammation. The findings suggest that a healthy diet may support a beneficial gut microbiome, potentially influencing PD risk and progression. The study highlights the importance of dietary interventions in managing PD symptoms and slowing disease progression.This study investigates the association between diet and gut microbiome composition in patients with Parkinson's disease (PD). Using 16S rRNA gene sequencing, the researchers assessed the gut microbiota in fecal samples from 85 PD patients in central California. Diet quality was evaluated using the Healthy Eating Index 2015 (HEI-2015), and the impact of diet on microbial diversity, composition, taxon abundance, and predicted metagenomic profiles was examined. Higher HEI scores and fiber intake were associated with an increase in anti-inflammatory butyrate-producing bacteria, such as *Butyricicoccus* and *Coprococcus* 1, while higher added sugar intake was linked to an increase in pro-inflammatory bacteria, such as *Klebsiella*. Predictive metagenomics revealed that bacterial genes involved in lipopolysaccharide biosynthesis decreased with higher HEI scores, and genes involved in taurine degradation decreased, indicating reduced neuroinflammation. The findings suggest that a healthy diet may support a beneficial gut microbiome, potentially influencing PD risk and progression. The study highlights the importance of dietary interventions in managing PD symptoms and slowing disease progression.