BILMOD: BILe Acid-gut Microbiome Axis MODification Through Diet Education for Colorectal Cancer Prevention

In this research study, the investigators are:

• Investigating the effect of more plant-based and less animal-based food intake on bile acid metabolomic composition in stool among individuals with a history of colorectal adenoma.
• Investigating the effect of more plant-based and less animal-based food intake on plasma bile acid metabolomic composition, the gut microbiome, circulating biomarkers and gene expression associated with colonic bile acid receptor activation and colorectal cancer among individuals with a history of colorectal adenoma.

Based on the following evidence:

• Growing evidence indicates that the gut microbiome and its metabolites play important roles in mediating the dietary effects on colorectal cancer risk
• Secondary bile acids are increasingly appreciated as important metabolites underlying the metabolic link between Western diet, the gut microbiome, and colorectal cancer
• Evidence suggests that secondary bile acids trigger a plethora of tumorigenic effects in the colon, including inflammation, oxidative DNA damage, and apoptosis resistance
• Epidemiological studies have revealed that a higher circulating level of secondary bile acids, particularly deoxycholic acid and lithocholic acid, was associated with an increased risk of colorectal cancer
• High fat intake has been repeatedly reported to increase secondary bile acids, but the findings on how other nutrients or foods in Western diet may influence secondary bile acids remain mixed

The research procedures include screening for eligibility, study intervention, and scheduling two clinical research visits: