(LB01-02-25) Influences of Meat Intake on Blood Trimethylamine N-oxide (TMAO) a Biomarker of Cardiometabolic Disease Risk in Humans: A Systematic Review of Literature

Objectives: Trimethylamine N-oxide (TMAO) is a gut-microbiota-dependent metabolite which has emerged as a potential mechanism to explain associations between meat consumption and cardiometabolic disease. However, the relationships between specific meat types or quantities on TMAO and related metabolites require a systematic analysis.

Methods: Researchers independently screened 2,023 studies published through March 2024 using PubMed, Cochrane, Scopus, Embase, Central, and CINAHL. Observational studies (OBS) and randomized controlled trials (RCTs) in humans (age 18+ years) that met inclusion criteria were extracted. Thirty-three articles, 18 OBS (6 prospective (PRO) and 12 cross-sectional (CS)) and 15 RCTs, were systematically reviewed to assess the relationships between meat consumption and blood TMAO and related metabolites (trimethylamine, carnitine, choline, betaine, and γ-butyrobetaine).

Results: The OBS results support that red meat (2 PRO and 4 CS) and fish/seafood (2 PRO and 3 CS) consumption are positively associated with higher TMAO concentrations, while poultry (1 CS) may have an inverse association. Carnitine concentrations were positively associated with red meat (2 PRO and 2 CS) and total meat (1 PRO and 3 CS) consumption. Results of the RCTs revealed that fish/seafood consumption resulted in higher concentrations in TMAO, carnitine, and betaine compared to red meat consumption. There were mixed findings on poultry consumption and its effects on TMAO and related metabolites. Higher intakes of red meat and fish/seafood presented elevated TMAO concentrations compared to lower intakes.

Conclusions: Observational and experimental studies consistently show that higher intakes of red meat and fish/seafood, but not poultry, relate to higher blood TMAO. Red meat consumption is also linked to higher blood carnitine. These results highlight the importance of meat types and quantities in modulating blood TMAO, an index of cardiometabolic disease risk.

Funding Sources: National Cattlemen’s Beef Association a contractor to the Beef Checkoff.