Urinary Levels of Trimethylamine‐N‐Oxide and Incident Coronary Heart Disease: A Prospective Investigation Among Urban Chinese Adults

Background Trimethylamine‐N‐oxide (TMAO), a diet‐derived, gut microbial–host cometabolite, has been associated with adverse cardiovascular outcomes in patient populations; however, evidence is lacking from prospective studies conducted in general populations and non‐Western populations. Methods and Results We evaluated urinary levels of TMAO and its precursor metabolites (ie, choline, betaine, and carnitine) in relation to risk of coronary heart disease (CHD) among Chinese adults in a nested case–control study, including 275 participants with incident CHD and 275 individually matched controls. We found that urinary TMAO, but not its precursors, was associated with risk of CHD. The odds ratio for the highest versus lowest quartiles of TMAO was 1.91 (95% CI, 1.08–3.35; P trend=0.008) after adjusting for CHD risk factors including obesity, diet, lifestyle, and metabolic diseases and 1.75 (95% CI, 0.96–3.18; P trend=0.03) after further adjusting for potential confounders or mediators including central obesity, dyslipidemia, inflammation, and intake of seafood and deep‐fried meat or fish, which were associated with TMAO level in this study. The odds ratio per standard deviation increase in log‐TMAO was 1.30 (95% CI, 1.03–1.63) in the fully adjusted model. A history of diabetes mellitus modified the TMAO–CHD association. A high TMAO level (greater than or equal to versus lower than the median) was associated with odds ratios of 6.21 (95% CI, 1.64–23.6) and 1.56 (95% CI, 1.00–2.43), respectively, among diabetic and nondiabetic participants (P interaction=0.02). Diabetes mellitus status also modified the associations of choline, betaine, and carnitine with risk of CHD; significant positive associations were found among diabetic participants, but null associations were noted among total and nondiabetic participants. Conclusions Our study suggests that TMAO may accelerate the development of CHD, highlighting the importance of diet–gut microbiota–host interplay in cardiometabolic health.