Assessment of Dietary Habits, Lifestyle Factors and Circulating Trimethylamine N-oxide Status in Moroccan Colorectal Cancer Patients: A Cross-Sectional Study

Background: Trimethylamine-N-oxide (TMAO) is a hepatic metabolic co-product derived from dietary precursors via gut microbiota-mediated biotransformation. Although recently implicated as a critical molecular bridge relating dietary patterns to diverse systemic pathologies, the precise impact of TMAO on colorectal cancer (CRC) pathogenesis, etiology, and progression remains largely unresolved.

Aims: This study aimed to investigate the associations between circulating TMAO levels and various clinical, dietary, and behavioral risk factors associated with colorectal carcinogenesis within a cohort of Moroccan patients.

Material and Methods: In this cross-sectional study, patients were consecutively recruited over a 12-month period from the Ibn Rochd University Hospital in Casablanca and the Mohammed V Military Hospital in Rabat. Face-to-face interviews were conducted to evaluate dietary intake, nutritional patterns, lifestyle behaviors, and clinical phenotypes. Whole blood samples were collected, and serum TMAO concentrations were quantified through liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS).

Results: Globally, no significant correlation was observed between circulating TMAO concentrations and the overall CRC risk. However, highly significant specific associations were identified between elevated TMAO levels and tumor localization at the Hepatic flexure. Furthermore, significant correlations emerged between TMAO concentrations and distinct CRC symptomatologies, including rectal bleeding volume, chronic diarrhea, narrowed stool caliber, tenesmus (the sensation of incomplete rectal emptying), and fatigue. Regarding dietary habits, high-protein dietary adherence was positively correlated with elevated circulating TMAO concentrations, whereas a high consumption of plant-based whole foods was inversely associated with serum TMAO concentrations. Additionally, socioeconomic status and alcohol intake were found to modulate serum TMAO profiles.

Conclusion: While these findings demonstrate no direct association between circulating TMAO levels and overall CRC risk, they underscore the clinical necessity of considering dietary patterns when interpreting TMAO biomarkers in oncological cohorts. These outcomes highlight the critical imperative to develop tailored nutritional guidelines for CRC patients and to implement structured nutritional education programs within oncology centers to promote a healthy and balanced diet as an essential component of comprehensive CRC management.