FOR PATIENTS WITH PD:  Inclusion Criteria:  Documented diagnosis of Parkinson's disease On Levodopa treatment  Exclusion Criteria:  History of GI diseases [except for hemorrhoids or occasional (<3 times a week) heartburn] like Inflammatory bowel disease or Celiac disease Antibiotic use within last 12 weeks Use of probiotic supplement over the prior 2 weeks except yogurt Intentional change in diet Chronic use of NSAIDS. A washout period of 3 weeks is needed before the subject could be enrolled into the study. Low does aspirin is allowed.  FOR CONTROL GROUP:  Inclusion Criteria:  No clinical evidence of neurological disorders including Parkinson's disease Live in the same household as the Parkinson's Disease patient or is a first degree relative of the PD patient.  Exclusion Criteria:  History of GI diseases [except for hemorrhoids or occasional (<3 times a week) heartburn] like Inflammatory bowel disease or Celiac disease Antibiotic use within last 12 weeks Use of probiotic supplement over the prior 2 weeks except yogurt Intentional change in diet Chronic use of NSAIDS. A washout period of 3 weeks is needed before the subject could be enrolled into the study. Low does aspirin is allowed.