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NCT Number: NCT07086833

The Food Environment, Microbial Cysteine Metabolism, and Cancer Disparities

The goal of this clinical trial is to learn if changing cysteine levels in the diet can influence how the body processes cysteine in Black and White individuals aged 45-75 with a history of non-cancerous polyps. The main questions it aims to answer are:

* At the beginning of the study, do Black participants have higher levels of cortisol (a stress hormone) and compounds made from cysteine in their blood when compared to White participants? * Does eating less cysteine lower the body's natural cysteine activity and lead to less gut bacteria that break down cysteine? * Does eating less cysteine lead to less inflammation in the gut and lower levels of markers of inflammation in the blood?

Research will compare a high cysteine diet and a low cysteine diet, and each participant will eat both diets.

Participants will be in the study for 11 weeks and 2 days. Over the course of the study, participants will:

* Eat a high cysteine diet for 3 weeks, and a low cysteine diet for 3 weeks * Eat a moderate cysteine diet for 1 week before each study diet * Complete surveys * Provide blood, stool, and saliva samples * Maintain food logs

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Key information

Conditions

Colorectal Cancer Colonic Diseases Colorectal Neoplasms Digestive System Diseases Digestive System Neoplasms Gastrointestinal Diseases Gastrointestinal Neoplasms Intestinal Diseases Intestinal Neoplasms Neoplasms Neoplasms by Site Rectal Diseases

Age range

45 year–75 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University Hospital Clinical Research Center, Indianapolis, Indiana, United States

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Low Cysteine Diet

Other

A diet low in cysteine, about 1.4 g/1000 kcal.

High Cysteine Diet

Other

A diet high in cysteine, about 3 g/1000 kcal.

Primary outcomes

  1. Colonic inflammation

    Time frame: Baseline, Week 1 (Day 8), Week 2 (Day 15), Week 4 (Day 29), Week 7 (Day 49), Week 8 (Day 57), Week 9 (Day 64), Week 11 (Day 78)

    Fecal calprotectin, a marker of intestinal inflammation, will be measured from 100 mg of stool collected at the respective timeframe using a CALPRO Calprotectin ELISA test.

  2. Fecal microbial content

    Time frame: Baseline, Week 1 (Day 8), Week 2 (Day 15), Week 4 (Day 29), Week 7 (Day 49), Week 8 (Day 57), Week 9 (Day 64), Week 11 (Day 78)

    Microbial genomic DNA will be extracted from stool obtained at the respective timeframe using a Qiagen DNeasy PowerSoil Kit. Genomic DNA will be fragmented using a Covaris S2 and processed into libraries using an Integrated DNA Technologies xGen DNA Library Prep Kit. Final libraries will be pooled and sequenced on an Illumina NovaSeq X using 25B chemistry.

  3. Systemic markers of inflammation

    Time frame: Baseline, Week 1 (Day 9), Week 2 (Day 16), Week 3 (Day 23), Week 4 (Day 30), Week 7 (Day 50), Week 8 (Day 58), Week 9 (Day 65), Week 11 (Day 79)

    Serum from blood collected at the respective timeframe will be analyzed in triplicate with the Bio-Plex® Precision Pro™ (Bio rad, Hercules, CA) human cytokine 10-plex immunoassay to detect IL-1β, IL-6, IFN-γ, TNF-α, IL-2, IL-4, IL-5, IL-10, IL-12 (p70) and IL-13.

Secondary outcomes

  1. Quantification of serum hydroxycortisol and cysteine metabolism markers

    Time frame: Baseline, Week 1 (Day 9), Week 2 (Day 16), Week 3 (Day 23), Week 4 (Day 30), Week 7 (Day 50), Week 8 (Day 58), Week 9 (Day 65), Week 11 (Day 79)

    Serum hydroxycortisol and measures of cysteine metabolism (cysteine, homocysteine, lanthionine, cystathionine, serine) will be determined using hydrophilic interaction liquid chromatography with triple quadrupole tandem mass spectrometry by the Purdue Metabolite Profiling Facility.

  2. Absolute and relative quantification of microbial cysteine metabolic genes

    Time frame: Baseline, Week 1 (Day 8), Week 2 (Day 15), Week 4 (Day 29), Week 7 (Day 49), Week 8 (Day 57), Week 9 (Day 64), Week 11 (Day 78)

    Microbial genomic DNA will be extracted from stool obtained at the respective timeframe using a Qiagen DNeasy PowerSoil Kit. To estimate gene content, metagenomic libraries will be constructed from stool DNA. Metagenomic data will be processed to filter potential host DNA sequences and remove low-quality reads. Raw shotgun data will be assembled using MEGAHIT and assembled contigs will be binned using MetaBAT2. Taxonomic classification of binned contigs will be performed using CAT/BAT and differences genera that have functional genes for sulfur metabolism will be assessed. Assembled and binned metagenomes will be surveyed for genes for cysteine metabolism using custom hidden Markov model (HMM) libraries.

  3. Exfoliated intestinal epithelial cell transcriptomics

    Time frame: Baseline, Week 1 (Day 8), Week 4 (Day 29), Week 8 (Day 57), Week 11 (Day 78)

    Exfoliated intestinal epithelial cells separated from stool collected at the respective timeframe with gene expression analysis

Other outcomes

  1. Psychosocial health

    Time frame: Baseline, Week 4 (Day 30), Week 8 (Day 58),Week 11 (Day 79)

    survey

  2. Medication use

    Time frame: Baseline, Week 4 (Day 30), Week 8 (Day 58),Week 11 (Day 79)

    survey

  3. Bowel habits

    Time frame: Baseline, Week 4 (Day 30), Week 8 (Day 58),Week 11 (Day 79)

    survey

Study contacts

Contact information is provided by the study sponsor or research team.

Patricia G Wolf, PhD, RD

CONTACT

[email protected]

765-494-1860

Sponsors and collaborators

Lead sponsor

Purdue University

Other

Collaborators

  • American Cancer Society, Inc.
  • Indiana University

Registry information

Important dates

Study start
2025
Primary completion
2027
Study completion
2027
First posted
Jul 25, 2025
Registry last updated
May 14, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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