If intestinal dysbiosis altered the prevalence of glutamine synthetase (GS) producing bacteria, dietary glutamate homeostasis could be impaired, leading to elevated plasma glutamate levels.<b>Objectives:</b> This study examined the degree of fluctuation in plasma glutamate levels seen with consumption of a protein shake in a cohort of ALS patients and family members from a single ALS center.<b>Methods</b>: Twenty six patients (87% of total cohort followed in the ALS center) underwent measurement of plasma amino acid analysis prior to and 1 hour following consumption of a 75 gm protein shake.