TMAO is a byproduct formed by gut bacteria digesting nutrients found in red meat, eggs and other animal products. New research finds high levels of TMAO in the blood predicts the future The role of FMO3 in metabolic diseases Unraveling the Formation Mechanisms of Trimethylamine N Oxide and Its Inhibition by Food Ingredients: Toward Cardioprotective Food Development Journal of Agricultural and Food Chemistry Did You Know? Some people report a fishy smell after supplementing with L carnitine. This happens because certain gut bacteria convert carnitine to trimethylamine, a malodorous compound found in rotting fish.