While SCFAs, including butyrate, are often considered beneficial for their anti-inflammatory and neuroprotective effects 100,101, findings by Sampson et al. 41 demonstrate that SCFAs can exacerbate neuroinflammation, microglial activation, and α-synuclein aggregation, leading to motor deficits in an α-synuclein-overexpressing mouse model of Parkinson’s disease. Here, SNCA is linked to Parkinson disease.