When to take L carnitine: Dosage, forms, and side effects Carnitine Rich Foods: Understanding L Carnitine and Its Benefits Loyal Trimethylaminuria: Understanding and Treating Fish Odor Syndrome Theres a reason why fish smell so bad! As a perfumer, Im a little sensitive to smells So I wondered why fish have such a strong fragrance, and why lemon seems to neutralize it So if youre a 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.