Controlled Feeding Experiment

Inclusion criteria

• Participant is capable of giving informed consent
• Participant is age 18 to 40 years

Exclusion criteria

• Diagnosis with Inflammatory bowel disease (IBD), celiac disease, or other chronic intestinal disorders.
• Baseline bowel frequency less than every 2 days or greater than 3 times daily.
• Current smoker.
• Body Mass Index (BMI) <18.5 of >35.
• Diabetes mellitus (DM)
• Diagnosis with coronary artery disease, congestive heart failure, or prior myocardial infarction.
• History of dyslipidemia or receiving treatment for hypercholesterolemia. This will be defined as a fasting LDL >160 mg/dL or a non-fasting total cholesterol >200 mg/dL or non-fasting HDL<40 mg/dl. Additionally, patients receiving drug therapy for hypercholesterolemia will be excluded.
• Prior bowel resection surgery.
• Contraindication to flexible sigmoidoscopy and biopsies. Patients with suppressed white blood count may be at increased risk of systemic infection following sigmoidoscopy with biopsies. As such, subjects with a white blood cell (WBC) count less than 3,500 or an absolute neutrophil count of less than 1,000 will be excluded. Patients with thrombocytopenia or with a coagulopathy may be at increased risk of bleeding complications after colonoscopic biopsies. As such, patients with a platelet count of less than 100,000 or an international normalized ratio (INR) greater than 1.2 will be excluded from the study.
• Student or employee of any one of the investigators.
• Pregnant women.
• Use of antibiotics in the prior 6 months.
• Use of antacids, non-steroidal anti-inflammatory drugs (NSAIDs), or dietary supplements in the preceding 2 weeks.
• Use of any of the following medications in the 4 weeks prior to randomization: proton pump inhibitors (PPI), histamine receptor antagonists, narcotics, tricyclic antidepressants, anticholinergics (e.g., hyoscamine), metoclopramide, anti-diarrhea medications, laxatives.
• HIV infection, AIDS, or other known conditions resulting in immunosuppression.
• Allergies or intolerance to the components of the study diets.
• Participant has experienced diarrhea within the two weeks prior to the first sigmoidoscopy. Diarrhea is defined as a change in bowel habits with an increased frequency or loose stools such that the stool could not be lifted with a fork.
• Any condition that the investigator feels may limit the volunteer's ability to complete the study protocol.