Customer reviews for Nutricost L Carnitine Tartrate Supplement Powder (100 Grams) 1 Gram per Serving; 100 Servings Walmart.com A recurring fishy odor could indicate a larger medical problem. Trimethylaminuria (Fish Odor Syndrome or TMAU) Stabilizing the enzyme in fish odor syndrome 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 Is L Carnitine Safe? Watch FIRST BEFORE Taking L Carnitine Supplements