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 Malodorous biogenic amines in Escherichia coli caused urinary tract infections in womena metabolomics approach Scientific Reports Frontiers Gut Metabolite Trimethylamine N Oxide in Atherosclerosis: From Mechanism to Therapy Fish odour syndrome CMAJ