In our findings, baseline reductions in piperine levels in PDL, PD-GBA1 (PDG), and prodromal LRRK2 (ProdL) groups versus controls underscore its neuroprotective promise in these cohorts, consistent with preclinical evidence, but the conclusion still requires longitudinal sampling, controlled dietary metadata, and mechanistic studies in genotype-specific PD models. Here, GBA1 is linked to Parkinson disease.