Epigallocatechin gallate (EGCG) is a major polyphenolic compound found in green tea and has been researched for its neuroprotective properties, including potential benefits for Parkinson's disease (PD). Preclinical studies, primarily in cell cultures and animal models, have shown that EGCG exhibits antioxidant, anti-inflammatory, and anti-apoptotic effects, all of which are relevant to the pathogenesis of PD. EGCG has been shown to reduce oxidative stress and protect dopaminergic neurons from toxin-induced degeneration in animal models. Some studies also suggest that EGCG may inhibit the aggregation of alpha-synuclein, a protein implicated in PD pathology.

However, clinical evidence in humans is extremely limited. There are very few human trials, and those that exist tend to focus on safety and pharmacokinetics rather than efficacy in PD patients. As such, most of the current support for EGCG’s use in Parkinson’s disease comes from laboratory and animal research rather than robust clinical trials. No major medical guidelines currently recommend EGCG as a treatment or adjunct for PD. Therefore, while there is a scientific rationale and preclinical evidence supporting further investigation, the actual evidence supporting its use in humans with Parkinson’s disease is weak at present.