The human gut contains a complex and metabolically active microbial ecosystem (microbiota). The gut microbiome has recently been proven to play an important role in cardiovascular disease and various other disorders. Among the microbiome-related metabolites, trimethylamine-N-oxide (TMAO) has drawn a lot of attention owing to its proatherogenic and prothrombotic properties. Thus, abnormality in circulating level of TMAO could be a risk factor for certain diseases.