Postbiotics such as butyrate and phenylbutyrate–TUDCA have demonstrated anti-inflammatory and neuroprotective effects, with clinical trials showing modest benefits [124]; butyrate restored microbial homeostasis and reduced SOD1 aggregation in ALS models, and a phase 2 clinical trial of phenylbutyrate–TUDCA showed slowed functional decline and reduced inflammatory biomarkers in patients with ALS, supporting further investigation in phase 3 trials. This evidence concerns the gene SOD1 and amyotrophic lateral sclerosis.