The Meals Study for Amyotrophic Lateral Sclerosis and Parkinson's Disease

Inclusion Criteria for Participants with ALS: * Meet the El Escorial Criteria for definite, probable, or possible ALS: * Definite ALS is defined as presence of upper motor neuron (UMN) and lower motor neuron (LMN) signs in the bulbar region and at 2 of the other spinal regions * Probable ALS is defined as presence of UMN and LMN in at least 2 regions with UMN signs rostral to LMN signs; probable ALS supported by laboratory results is defined as presence of UMN in 1 region with electromyographic evidence of LMN involvement in another region * Possible ALS is defined as presence of UMN and LMN in 1 region or UMN in 2 or 3 regions (monomelic ALS, progressive bulbar palsy, and primary lateral sclerosis) * Voluntarily participate and able to consent * Have internet access * Willing to communicate by telephone or teleconferencing, and email * Minimum age of 30 years old * Able to masticate (chew) and swallow at the time of the study * Willing to return to the clinic eight weeks after enrolling for a regularly scheduled visit and post intervention data collection, or if they are not patients of the clinical sites, then they are willing to come to the clinic twice for study activities (once at enrollment and once upon exiting). * Patient (and their caregiver, if needed) must be willing and able (in the Investigator's opinion) to comply with all study requirements Exclusion Criteria for Participants with ALS: * Patients that require a special diet (celiac/gluten free, vegetarian, or vegan) * Antibiotic use in past 6 months * History of bowel diseases or cancer (e.g., irritable bowel syndrome, celiac sprue, Crohn's * Younger than age 30 * Unable to provide consent * Feeding by tube feed or primarily liquid diets * Unable to masticate or swallow. Inclusion Criteria for Participants with PD: * Meet clinical criteria for PD per the MDS clinical criteria (Postuma et al, Movement Disorders, * 2015\) as determined by the treating Movement Disorder specialist * Hoehn Yar \< 2.5, as determined by the treating Movement Disorder Specialist. * Be 50 to 80 years of age upon enrollment. * Levodopa daily equivalents of no more than 500 a day * Subjects are within five years of the onset of symptoms at time of study enrollment. * Participants agree not to change PD medications during the 7-week dietary intervention. * Voluntarily participate and able to consent * Able to masticate (chew) and swallow at the time of the study * Have internet access * Willing to communicate by telephone or teleconferencing, and email Exclusion Criteria for Participants with PD: * May not be taking medications concerning for a drug induced parkinsonism two years prior to * study entry such as antipsychotics, metoclopramide (Reglan), prochlorperazine (Compazine), * promethazine (Phenergan) or amiodarone * The movement disorder specialist must find no red flags for concern for atypical or Parkinson's Plus per the MDS diagnostic criteria (Postuma et al) * Patients that require a special diet (celiac/gluten free, vegetarian, or vegan) * Antibiotic use in past 6 months * History of bowel diseases or cancer (e.g., irritable bowel syndrome, celiac sprue, Crohn's Disease, colorectal cancer) * Unable to provide consent or struggling with major cognitive concerns as determined by the * treating Movement Disorder specialist * Feeding by tube feed or primarily liquid diets * Unable to masticate or swallow. Inclusion Criteria for Healthy Controls: * Voluntarily participate and able to consent * Able to speak, read, and write English * Internet access, * Willing to communicate by telephone or teleconferencing, and email * Minimum age of 30 years * Able to masticate (chew) and swallow at the time of the study * Willing to visit the clinic two times to complete study activities * Patient (and their caregiver, if needed) must be willing and able (in the Investigator's opinion) to * comply with all study requirements Exclusion Criteria for Healthy Controls: * Healthy people who require a special diet (celiac/gluten free, vegetarian, or vegan) * Antibiotic use in past 6 months * History of bowel diseases or cancer (e.g., irritable bowel syndrome, celiac sprue, Crohn's Disease, colorectal cancer) * Younger than age 30 * Unable to consent * Feeding by tube feed or primarily liquid diets * Diagnosis with any neurodegenerative disease (e.g., Alzheimer's disease, Parkinson's disease, multiple sclerosis, peripheral neuropathies).