Walnuts and Colon Health

Inclusion Criteria

• Men and women between the ages of 39-75 years old who meet the criteria of one of the following groups and are eligible to undergo a routine screening or surveillance colonoscopy for colorectal cancer (CRC):
• Individuals who have a family history of colon polyps or CRC in a first-degree relative diagnosed with CRC under the age of 65 years, or
• Individuals who are referred for colonoscopy following a positive fecal immunochemical test (FIT) or a positive Cologuard screening test and have not had a high-quality colonoscopy in the past 3 years, or
• Individuals who have a personal history of colon polyps
• Willing and able to provide written informed consent for study participation
• Willing to consume 2 ounces (56 grams) of walnuts daily for 3 weeks
• Willing to avoid intake of EA/ET-rich foods and beverages (e.g., pomegranates, hazelnuts, pistachios, strawberries, raspberries, blackberries, oak-aged wines, and other items on a list given by researchers) and fermented dairy products containing viable Bifidobacteria or Lactobacilli)
• Willing to stop taking dietary supplements, including probiotics
• Willing to have two separate blood draws, as well as urine and stool collections
• Willingness to comply with all study requirements

Exclusion Criteria

• Individual has a personal history of CRC, or a history of any malignancy (other than skin cancer) within the past 5 years
• Individual meets the Amsterdam criteria for Lynch Syndrome or has a history of familial adenomatous polyposis (FAP)
• Individual has been treated with immunosuppressive agents or systemic steroids, excluding inhalers, at least two weeks prior to the Screening Visit and for the duration of the study
• Use of antibiotics at least one month prior to the Screening Visit and for the duration of the study
• Patients with severe medical illness or those at high risk for anesthesia, as determined by good clinical practice
• Current evidence or previous history of ulcerative colitis or Crohn's disease
• Colonoscopy performed for reasons other than screening or surveillance for CRC
• HIV infection, chronic viral hepatitis
• Allergy to walnuts or hypersensitivity to tree nuts
• Peri-menopausal women with any chance or plan of pregnancy
• Individuals with blood coagulation disorders or on anti-coagulant therapy
• Any other condition that, in the opinion of the PI, might interfere with study objectives
• No race/ethnicity, language or gender exclusions for this study