L Carnitine Linus Pauling Institute Oregon State University Comparison of short term and long term effects of peroral L carnitine intake: clinical implications of elevated TMAO levels in cardiovascular complications Trimethylaminuria: Understanding and Treating Fish Odor Syndrome L Carnitine Viagra: What the Research Shows About This Combo for Energy and Performance 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.