An Aspect of Physiological Functions of Choline: Trimethylamine-N-oxide

Abstract

Recently, Hibino has reviewed bioactivity of choline in the February issue of this journal¹⁾. This review helps serve collective comprehension of the related filed of choline bioactivity, but the information regarding the trimethylamine-N-oxide (TMAO), a well-known metabolite of choline with the plausible atherogenic potential, is not introduced. TMAO is a crucial compound to recognize the safety aspects of choline consumption. A portion of choline ingested is converted by gut bacteria to trimethylamine (TMA), which is then absorbed from the intestine and transported to the liver, where it is enzymatically converted to TMAO. As phsophatidylcholine (PC), the major dietary source of choline, is known to be antiatherogenic, the situation is really complicated. Egg is a major source of choline as PC (L type, 147 mg) and consumption of less than 2 eggs per day may not increase the blood level of TMAO, though not conclusive. Involvement of gut microbes is one of the recent exciting topics concerning the cognitive role of choline.