Trimethylamine N-Oxide (TMAO) in Seafoods: Shared Mechanisms Between Fish and Humans for Forming Gut-Microbial TMAO: Overview of Animal TMAO-Yield Potential

Existence of Trimethylamine N-oxide (TMAO) and trimethylamine (TMA) are well recognized through our multiple human activities. Most of them are derived from quaternary ammoniums widely distributed in natural products, which have N-trimethyl moiety. There could also be some inhibitors to reduce their yield. TMAO is known as a representative component in seafood and is recently gaining large attention. TMAO is formed mostly from choline and carnitine in animal products by mediating gut microbes and host monooxygenase in the human body. Teleost tilapia also has a similar mechanism well mediating choline. In marine habitants, TMAO is utilized as an osmolyte. In human, however, the endogenous TMAO is reported to be associated with a risk of cardiovascular events. During the organic evolution, marine creatures could develop utilizing TMAO while avoiding risks. This article, therefore, reviews and characterize the TMAO/TMA having different profiles, and consider the possible inhibitors preventing undesired metabolisms, to try to find clues of the TMAO subjects and consider possibilities and prospects.