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 30-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.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
PREVENTION
Masking
NONE
Enrollment
200
Participants consume 2 ounces of walnuts daily for 21 days
UConn Health
Farmington, Connecticut, United States
RECRUITINGWeill Cornell Medicine
New York, New York, United States
RECRUITINGBacterial composition and taxonomy changes in the fecal microbiome
Bacterial composition and taxonomy changes in the fecal microbiome will be assessed using 16 Svedberg unit (16S) ribosomal ribonucleic acid (rRNA) sequencing, at day 7 (post-washout/pre-walnut supplementation) and at day 28 (post-walnut supplementation).
Time frame: Day 7 and Day 28
Bacterial diversity changes and strain-level variations in the fecal microbiome
Bacterial diversity/abundance changes and strain-level variations in the fecal microbiome will be assessed using metagenomic shotgun sequencing at day 7 (post-washout/pre-walnut supplementation) and at day 28 (post-walnut supplementation).
Time frame: Day 7 and Day 28
Bacterial gene expression profile changes in the fecal microbiome
Bacterial gene expression profile changes in the fecal microbiome will be assessed using metagenomic ribonucleic acid (RNA) sequencing at day 7 (post-washout/pre-walnut supplementation) and at day 28 (post-walnut supplementation).
Time frame: Day 7 and Day 28
Urolithin levels in urine
Urolithin levels will be measured in urine by ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry at day 0 (baseline/pre-washout), day 7 (post-washout/pre-walnut supplementation) and day 30 (post-walnut supplementation/end of study).
Time frame: Day 0, Day 7 and Day 30
Association of urolithin levels with presence (and type) of colonic lesions
Baseline urolithin levels measured in the urine by ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry will be associated with the presence (and type) of colonic lesions (e.g., advanced adenomas (AAs) or sessile serrated adenomas/polyps (SSA/Ps)) detected during the colonoscopy procedure at the end of the study (day 30).
Time frame: Day 30
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Correlation of urolithin levels with fecal microbiome composition
Detailed statistical analyses will be used to correlate urolithin formation with the composition of the fecal microbiome at day 7 (post-washout/pre-walnut supplementation) and at day 28 (post-walnut supplementation).
Time frame: Day 7 and Day 28
Correlation of colonic lesion gene expression with urolithin production
Colonic lesion (AAs and SSA/Ps) biopsies obtained at the end of the study (day 30) during the colonoscopy procedure will undergo DNA sequence-based analysis to determine gene expression profiling. These results will be compared to urinary urolithin levels measured at baseline to establish correlations between urolithin production and colorectal cancer risk markers.
Time frame: Day 30
Association of urolithin levels with the immune composition of the tumor microenvironment
FFPE colon polyp tissue sections will be analyzed by the NCI Imaging Core (Frederick, MD) using imaging mass cytometry (IMC) to determine immune cell populations present within the tumor microenvironment. This data will be used to establish correlations with urolithin production.
Time frame: Day 30
Short-chain fatty acid composition in stool
Short-chain fatty acids in freeze-dried stool samples will be measured using differential mobility separation at day 7 (post-washout/pre-walnut supplementation) and at day 30 (post-walnut supplementation).
Time frame: Day 7 and Day 30
Bile acid metabolism in stool
Primary and secondary bile acids in freeze-dried stool samples will be analyzed using standard liquid chromatography-mass spectrometry methods at day 7 (post-washout/pre-walnut supplementation) and at day 30 (post-walnut supplementation).
Time frame: Day 7 and Day 30
Inflammatory markers in blood
Markers of systemic inflammation associated with adenoma risk will be measured in plasma using commercial enzyme-linked immunoassay (ELISA) kits at day 7 (post-washout/pre-walnut supplementation) and at day 30 (end of study).
Time frame: Day 7 and Day 30
Correlation of dietary behavior with presence (or absence) of colonic polyps
Overall diet quality and habits documented on brief food questionnaires will be analyzed by NutritionQuest at day 7 (post-washout/pre-walnut supplementation). Dietary behavior data will be correlated with the presence or absence of colonic polyps detected during the colonoscopy procedure at the end of the study (day 30).
Time frame: Day 7 and Day 30
Correlation of dietary behavior with fecal microbiome composition and diversity
Dietary behavior data documented on 3-day dietary records will be analyzed by Nutrition Data System for Research software. This data will be correlated with fecal microbiome composition and diversity at day 7 (post-washout/pre-walnut supplementation) and at day 30 (post-walnut supplementation).
Time frame: Day 7 and Day 30
Correlation of dietary behavior with urolithin production
Dietary behavior data documented on 3-day dietary records will be analyzed by Nutrition Data System for Research software. This data will be correlated with urolithin levels at day 7 (post-washout/pre-walnut supplementation) and at day 30 (post-walnut supplementation).
Time frame: Day 7 and Day 30