Comparison of short term and long term effects of peroral L carnitine intake: clinical implications of elevated TMAO levels in cardiovascular complications Trimethylaminuria: Definition, symptoms, and more IV Carnitine Therapy Energy Boost & Metabolism Support Minnerva Clinic The main reason why people may experience a fishy taste, smell, or burp when taking #fishoil is that they are not taking a high quality #fishoilsupplement. When it comes to manufacturing 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.