Walnuts and Colon Health

  • End date
    Dec 31, 2026
  • participants needed
  • sponsor
    UConn Health
Updated on 7 October 2022
Accepts healthy volunteers


The purpose of this research study is to examine whether adding walnuts to your diet can have a beneficial effect on the gut bacteria population, inflammatory markers in the blood, and the tissue that lines the inside of the colon.


This is a 29-day dietary intervention study where participants will be asked to consume 2 ounces of walnuts daily for 21 days, and at the end of the study period they will come in for a routine colonoscopy. After being informed about the study and potential risks, participants giving written informed consent will first start a 7-day wash-out period where they will be asked to avoid foods high in ellagitannins for the duration of the study. In addition, participants will be asked to complete food and activity questionnaires, a walnut consumption log, and two sets of 3-day dietary records during their participation in the study. Participants will also be asked to provide three urine samples, two blood samples, and two stool samples at multiple time points, and 8-10 colon tissue specimens (biopsies) will be collected during their colonoscopy procedure for the purposes of this study.

Condition Colorectal Cancer, Diet Habit
Treatment walnuts
Clinical Study IdentifierNCT05195970
SponsorUConn Health
Last Modified on7 October 2022


Yes No Not Sure

Inclusion Criteria

Individuals in one of the following groups
Men and women between the ages of 40 to 75 years old, who are scheduled to undergo a routine screening or surveillance colonoscopy for colorectal cancer (CRC) and have a family history of CRC in a first degree relative diagnosed with CRC under the age of 65 years, or
Men and women between the ages of 45 to 75 years old, who are referred for colonoscopy following a positive fecal immunochemical test (FIT) and have not had a high quality colonoscopy in the past 3 years
Willing and able to provide written informed consent for study participation
Willing to consume 2 ounces of walnuts daily for 3 weeks
Willing to avoid intake of ellagic acid/ellagitannin-rich foods (e.g., pomegranates, hazelnuts, pistachios, strawberries, raspberries, blackberries, oak-aged wines, and other food 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 2 separate blood draws, as well as urine and stool collections
Willing 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
Clear my responses

How to participate?

Step 1 Connect with a study center
What happens next?
  • You can expect the study team to contact you via email or phone in the next few days.
  • Sign up as volunteer  to help accelerate the development of new treatments and to get notified about similar trials.

You are contacting

Investigator Avatar

Primary Contact


Additional screening procedures may be conducted by the study team before you can be confirmed eligible to participate.

Learn more

If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

Learn more

Complete your scheduled study participation activities and then you are done. You may receive summary of study results if provided by the sponsor.

Learn more

Similar trials to consider


Browse trials for

Not finding what you're looking for?

Every year hundreds of thousands of volunteers step forward to participate in research. Sign up as a volunteer and receive email notifications when clinical trials are posted in the medical category of interest to you.

Sign up as volunteer

user name

Added by • 



Reply by • Private

Lorem ipsum dolor sit amet consectetur, adipisicing elit. Ipsa vel nobis alias. Quae eveniet velit voluptate quo doloribus maxime et dicta in sequi, corporis quod. Ea, dolor eius? Dolore, vel!

  The passcode will expire in None.

No annotations made yet

Add a private note
  • abc Select a piece of text from the left.
  • Add notes visible only to you.
  • Send it to people through a passcode protected link.
Add a private note