Tolerability and Efficacy of L-Serine in Patients With Amyotrophic Lateral Sclerosis (ALS)

Inclusion Criteria: * Diagnosis of probable or definite ALS * ALSFRS-R score \>25 and FVC score ≥ 60% predicted * If currently taking Riluzole and/or Edaravone/Radicava must be on stable dose for 3 months prior to Baseline/Screening. If the dosing has not been stable for 3 months prior to Baseline/Screening or if stopped due to an adverse event, the waiting period off the medication will be 7 days. If not on either of these medications may start if desired either or both medications after enrollment into study. Exclusion Criteria: * Diagnosis of probable or definite ALS more than 3 years prior to study enrollment * Diagnosis or previous history of ischemic stroke, brain tumor, uncontrolled diabetes, renal insufficiency, or severe hypertension. * Diagnosis or previous history of comorbid progressive neurodegenerative disease such as Alzheimer's disease, Parkinson's disease, Lewy Body disease, Pick's disease, Huntington's disease, Progressive Supranuclear palsy. ALS patients diagnosed with frontotemporal dementia will not be excluded from this study. * Diagnosis or previous history of symptomatic peripheral neuropathy. Patients with findings of peripheral neuropathy on electrodiagnostic tests only but no clinical symptoms at the time of enrollment are eligible. * Undergoing any chemotherapy or radiation therapy for any cancer * Any medical condition likely to interfere with the conduct of the trial or survival of the patient during this study period * Pregnant women or women who are breast feeding * Has taken L-Serine supplement within 30 days prior to start of study drug