The effects of the Mediterranean Diet and Western Diet on gut microbiota and Parkinson’s Disease. The MD is composed of Omega-3 PUFA, plant protein, grains, and nuts. The MD increases concentrations of Roseburia, Faecalibacterium prausnitzii and Eubacterium, while lowering concentrations of Bilophila, Ruminococcus torques, Coprococcus comes. The MD effects on PD include delaying onset, improving executive function in PD patients, upregulating BDNF production, alleviating inflammation, improving intestinal barrier integrity and stimulating GLP-1 secretion, which in turn increases DAT expression and reduces dopaminergic neuron death. The WD is composed of animal proteins, fats and sugars. The WD increases concentrations of Ruminococcus torques and Escherichia coli, while reducing levels of Eubacterium, Roseburia and Bifidobacterium in the gut. The WD effects on PD include promoting gut inflammation via LPS/TLR4 activity, NLRP3 inflammasome innate reprogramming, increasing neuroinflammation, reducing striatal dopamine and D2R, leading to nigrostriatal dopaminergic loss and α-synuclein accumulation. Abbreviations: PUFA, poly-unsaturated fatty acids; BDNF, brain derived neurotrophic factor; GLP-1, glucagon-like peptide 1; DAT, dopamine transporter; LPS, lipopolysaccharides; TLR-4, toll-like receptor 4; D2R, dopamine 2 receptor.