Does L carnitine cause fishy body odor? Surprising Truth and Solutions Tonum L Carnitine (500mg) NutraBio Brands L carnitine supplements can cause a fishy odor in the breath, sweat, and urine. This is likely due to the formation of trimethylamine (TMA). TMA is also responsible for the pungent smell of 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. Unraveling the Formation Mechanisms of Trimethylamine N Oxide and Its Inhibition by Food Ingredients: Toward Cardioprotective Food Development Journal of Agricultural and Food Chemistry Acetyl L Carnitine Alpha Lipoic Acid Erectile Dysfunction: What the Evidence Shows and Practical Considerations