Vitamins and essential metals have been studied as potential risk and prognostic factors in amyotrophic lateral sclerosis (ALS). This study aimed to evaluate the prevalence of inadequate micronutrient intake in ALS patients, comparing subgroups according to the disease severity. Data were obtained from the medical records of 69 individuals. Assessment of disease severity was determined by the revised ALS Functional Scale (ALSFRS-R), using the median as the cutoff. The prevalence of inadequate micronutrient intake was estimated using the Estimated Average Requirements (EAR) cut-point method. The prevalence of inadequate vitamin D, E, riboflavin, pyridoxine, folate, cobalamin, calcium, zinc, and magnesium intake was considered severe. Patients with lower ALSFRS-R scores had lower intakes of vitamin E (p< 0.001), niacin (p= 0.033), pantothenic acid (p= 0.037), pyridoxin (p= 0.008), folate (p= 0.009) and selenium (p= 0.001). Therefore, ALS patients should be monitored regarding dietary intake of micronutrients essential in neurological processes.