Identification of trimethylamine N-oxide (TMAO)-producer phenotype is interesting, but is it helpful?

We read with great interest the paper by Wu et al 1 reporting on the development of a carnitine challenge test to facilitate the identification of trimethylamine N-oxide (TMAO)-producer phenotype and host-diet-gut dysbiosis. Such a test assumes that, according to a partial reading of the literature, TMAO plays a key role in cardiovascular disease (CVD). Accordingly, the authors assert the implied importance of the potential for adverse CVD-inducing actions of compounds generating TMAO subsequent to the action of gut microbiota on dietary carnitine. However, a more objective reading of the literature shows that the biomedical community is still debating the potential involvement of TMAO in inducing