Diet quality and prodromal Parkinson's disease probability in isolated REM sleep behavior disorder

•A diet that lowers oxidative stress reduces the prodromal Parkinson's disease (pPD) probability.•Diet quality assessed by Recommended Food Score (RFS) did not differ between the general population and iRBD patients.•Among patients with iRBD, the probability of pPD did not differ between the high and low RFS groups.•In patients aged <70 years, legume consumption was negatively correlated with pPD probability.