Dietary Intervention and Gastrointestinal Function in Patients With Parkinson's Disease

Inclusion Criteria: * Physician-diagnosed Parkinson's disease aged 21-85 years * Hoehn \& Yahr stage \<3 * Currently living in the same household with a healthy spouse/partner who meets study eligibility criteria and is willing to participate * Willing and able to complete informed consent in English * Willing to complete daily and weekly questionnaires and 6 dietary recalls over approximately 7 weeks * Willing to avoid beer, wine, and cocktails on the day before and the day of the sugar probe tests. * Willing to provide urine and stool samples during the study collection periods. * Willing and able to fast (no food or drink, except water or tea) for a prolonged period of time during study urine collections. * Willing to maintain usual diet through the pre-baseline period * Willing to make dietary changes to follow a Mediterranean dietary pattern during the intervention period. * Willing to discontinue taking prebiotic, fiber, probiotic, herbal, or high-dose vitamin or mineral supplements that may impact inflammation during the pre-baseline period and throughout the study protocol. * Willing to limit use of oral laxative medication to an "as-needed basis" (i.e. \<3 times per week) during the full length of the study * Willing to avoid high intensity exercises two days prior to and the day of the permeability tests. These tests will be done on two occasions. * Willing to provide a social security number to receive study payment. Exclusion Criteria: * Does not meet above criteria * Atypical or secondary Parkinsonism * History of deep brain stimulation * Daily use of NSAIDs in the last 3 months or incidental use in the last 2 weeks prior to screening. * Daily use of anticholinergics or prokinetic agents * Use of enemas or suppositories to alleviate constipation * Use of another investigational product within 3 months of the screening visit. * Antibiotic use within 2 months from the day of stool collection * Good adherence to the Mediterranean diet during the pre-baseline period (score \>6) based on the 14-item Mediterranean Diet Assessment Tool * Physician-diagnosed gastrointestinal disease or condition (such as ulcerative colitis, Crohn's disease, gastroparesis, cancer, peptic ulcer disease, Celiac disease, short bowel disease, ileostomy, colostomy) other than gastroesophageal reflux or diverticular disease