TMAU: Diet to reduce a fishy odour Dietitian's Life L Carnitine: Benefits, Uses, Side Effects, and More 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 Trimethylamine N Oxide in Aquatic Foods Journal of Agricultural and Food Chemistry l carnitine: Nutrition, pathology, and health benefits ScienceDirect Potential Adverse Effects of L Carnitine Marnys