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. Urine normally has a slight smell, but some unusual and strong smells may be a sign that something's wrong. Stabilizing the enzyme in fish odor syndrome SirenLabs L Carnitine Elite Burn GNC 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, L Carnitine Linus Pauling Institute Oregon State University