Dietary cysteine, gut microbes, and colorectal cancer risk
Official title: The Food Environment, Microbial Cysteine Metabolism, and Cancer Disparities
Run by Purdue University · NCT07086833 · Data updated 2026-11-12
This trial will see if eating lower-cysteine versus higher-cysteine diets changes how the body and gut bacteria handle cysteine and reduces gut inflammation in Black and White adults aged 45–75 who previously had non-cancerous colon polyps.
Quick facts
| Study type | Interventional |
|---|---|
| Ages | 45 Years to 75 Years |
| Sex | All |
| Enrollment | 40 (estimated) |
| Sponsor | Purdue University Academic / other |
| Locations | 2 sites (Indianapolis, Indiana and 1 other locations) |
| Status | Recruiting |
| Started | August 18, 2025 |
| Main results expected | December 1, 2027 |
| Study ends | December 1, 2027 |
| Registry record updated | May 14, 2026 |
| Trial ID | NCT07086833 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Black or Non-Hispanic White adults aged 45–75 with a history of three or more adenomatous polyps or an adenomatous polyp >1 cm in the past five years who can follow controlled diets and provide blood, stool, and oral samples are ideal candidates.
✕Probably not a fit
People who recently used antibiotics, have active cancer or a genetic CRC predisposition, have significant dietary restrictions that prevent following the protocol, or cannot comply with controlled feeding and sample collection are unlikely to benefit from participation.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
This is a controlled dietary crossover trial in which each participant follows a high-cysteine diet for three weeks and a low-cysteine diet for three weeks, with the full participation lasting about 11 weeks. Researchers will collect blood, stool, and oral-wash samples and perform 24-hour dietary recalls to measure cysteine-related metabolites, gut microbial composition and function, and markers of intestinal and systemic inflammation. The protocol compares baseline differences between Black and Non-Hispanic White participants and measures within-person changes after each diet period. The goal is to link dietary cysteine exposure to microbial cysteine metabolism and inflammation that are relevant to colorectal cancer risk.
Why it matters
Potential benefit: If successful, this work could identify a simple dietary change that lowers gut inflammation and microbial processes linked to colorectal cancer risk in high-risk adults.
How similar studies have gone: Observational and mechanistic studies have linked sulfur amino acid metabolism and microbial hydrogen sulfide to colorectal cancer risk, but controlled dietary interventions that specifically manipulate cysteine are limited, making this approach relatively novel.
Who can join: the full rules
Show full inclusion / exclusion criteria
Inclusion Criteria: * Aged 45-75 * Up to date with CRC screening colonoscopy with a high risk of CRC, defined as a history of 3 or more adenomatous polyps (APs) or an AP \>1 cm in the past 5 years * Identify as Black or Non-Hispanic White * If female, no menstrual period for at least six months * Willingness to donate oral wash and stool samples * Willingness to complete 24-hour dietary recalls Exclusion Criteria: * Antibiotic use within the last 6 months * Abnormal gastrointestinal transit * A history of organ transplantation * Use of illicit drugs, combustible tobacco, or dietary supplements * Pre- or probiotics within the last two months * A history of cancer treatment within the past 12 months * CRC or a genetic predisposition to CRC * A baseline body weight \> 450 lbs * Weight gain or loss \> 4 kg 3 months prior to study * Significant food allergies, food preferences or therapeutic or vegetarian diets * Menstrual cycle within the last 6 months * Antibiotics in the last 2 months * Cannot keep a food record for 7 consecutive days during screening after detailed instruction * Significant medical conditions * History of eating disorders * Alcoholism * Individuals under the age of 18
Where it's running
-
Purdue Clinical Research Center
West Lafayette, Indiana, United States Recruiting -
University Hospital Clinical Research Center
Indianapolis, Indiana, United States Not yet recruiting
Study contacts
- Study coordinator: Patricia G Wolf, PhD, RD
- Email: wolfpm@purdue.edu
- Phone: 765-494-1860
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.