Inclusion Criteria:  Parkinson's disease patients who are untreated  Exclusion Criteria:  Occupation expected to change the microbiome (e.g. sanitation worker) Treatment with medications that may induce parkinsonism (e.g. metoclopramide, typical or atypical antipsychotic agents) Treatment within 12 weeks with oral or intravenous antibiotics Known diagnosis of inflammatory bowel disease Symptomatic organic gastrointestinal (GI) disease (other than hemorrhoids and hiatal hernia) or abdominal surgeries for symptomatic gastrointestinal disease such as bowel resection, diverticular surgery, colostomy; subjects with a history of an appendectomy or gallbladder removal for non-cancerous disease more than 5 years prior to presentation are allowed. Symptomatic functional GI disease that significantly impairs intestinal motility such as scleroderma or use of GI motility drugs Acute illness requiring immediate hospitalization Pre-existent conditions as below: Liver disease (cirrhosis or persistently abnormal AST or ALT that are 2X> normal); Kidney disease (creatinine>2.0 mg/dL); Uncontrolled psychiatric illness; Clinically important lung disease or heart failure; HIV disease; Alcoholism, unreliable drinking history; or consumption of alcohol more than 3 times a week or binge drinking or drinking more than or equal to 3 drinks per occasion; Transplant recipients; Diabetes; BMI > 30 Clinically significant dehydration or clinically detectable ascites or peripheral edema or cardiac failure Presence of short bowel syndrome or severe malnutrition with ideal body weight < or = 90% Use of immunosuppressive medications in 3 months prior to enrollment Anti-inflammatory medication use within 3 weeks of enrollment. Chronic use of diuretics