Adding walnuts to diet for colon health

Microbiota, Metabolites and Colon Neoplasia

Not applicable Interventional UConn Health · NCT05195970

This study is testing whether eating walnuts every day can improve gut health and lower the risk of colon cancer.

Quick facts

PhaseNot applicable
Study typeInterventional
Enrollment200 (estimated)
Ages39 Years to 75 Years
SexAll
SponsorUConn Health Academic / other
Locations2 sites (Farmington, Connecticut and 1 other locations)
Trial IDNCT05195970 on ClinicalTrials.gov

What this trial studies

This research examines the effects of incorporating walnuts into the diet on gut bacteria, inflammatory markers, and colon tissue health. Participants will consume 2 ounces of walnuts daily for 21 days, followed by a routine colonoscopy to collect tissue samples. The study includes a wash-out period and requires participants to complete dietary logs and provide urine, blood, and stool samples at various points. The goal is to assess the impact of walnuts on colorectal cancer risk factors.

Who should consider this trial

Good fit: Ideal candidates are men and women aged 39-75 with a family history of colorectal cancer, a personal history of colon polyps, or those referred for colonoscopy after a positive screening test.

Not a fit: Patients who do not meet the eligibility criteria or have contraindications to walnut consumption may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide insights into dietary interventions that improve gut health and reduce colorectal cancer risk.

How similar studies have performed: While dietary interventions for gut health have been explored, this specific approach using walnuts is relatively novel and has not been extensively tested.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

1. 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):

   1. 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
   2. 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
   3. Individuals who have a personal history of colon polyps
2. Willing and able to provide written informed consent for study participation
3. Willing to consume 2 ounces (56 grams) of walnuts daily for 3 weeks
4. 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)
5. Willing to stop taking dietary supplements, including probiotics
6. Willing to have two separate blood draws, as well as urine and stool collections
7. Willingness to comply with all study requirements

Exclusion Criteria:

1. Individual has a personal history of CRC, or a history of any malignancy (other than skin cancer) within the past 5 years
2. Individual meets the Amsterdam criteria for Lynch Syndrome or has a history of familial adenomatous polyposis (FAP)
3. 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
4. Use of antibiotics at least one month prior to the Screening Visit and for the duration of the study
5. Patients with severe medical illness or those at high risk for anesthesia, as determined by good clinical practice
6. Current evidence or previous history of ulcerative colitis or Crohn's disease
7. Colonoscopy performed for reasons other than screening or surveillance for CRC
8. HIV infection, chronic viral hepatitis
9. Allergy to walnuts or hypersensitivity to tree nuts
10. Peri-menopausal women with any chance or plan of pregnancy
11. Individuals with blood coagulation disorders or on anti-coagulant therapy
12. Any other condition that, in the opinion of the PI, might interfere with study objectives
13. No race/ethnicity, language or gender exclusions for this study

Where this trial is running

Farmington, Connecticut and 1 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Colorectal CancerDiet HabitColorectal cancerMicrobiomeUrolithinWalnutsDiet habitInflammatory markers
Last reviewed 2026-06-09 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.