Amazon.com: 5% Nutrition Rich Piana Liquid L Carnitine 3150 Premium 4 Source Blend + GBB, The Super Carnitine (Mandarin Orange) : Health & Household TMAU: Diet to reduce a fishy odour Dietitian's Life Trimethylaminuria: Definition, symptoms, and more Your urine's smell can reveal a lot about your health. A strong ammonia like odor could indicate kidney stress, while a fruity scent may suggest ketones. Sweet smelling urine might point to diabetes risk, 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.