Why does my pee smell after I eat asparagus? - Mike S., Philadelphia

Hi Mike,
The phenomenon is known as asparagusuria, but it doesn’t happen with everyone. The smell is due to sulfur compounds in the urine and several have been identified, including S-methyl thioesters. The source of these compounds in the asparagus and how they get into the urine is unknown. The ability to produce the compounds may be genetically determined. In one study, 43% of urine samples taken after subjects ate asparagus had the odor (lucky testers) but other researchers disagree, concluding from a separate study that everyone produces offensive urine after eating asparagus, but not everyone can smell the offending compound; it’s called specific anosmia or smell blindness.

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Dr. Phil Handel is the Program Director for Drexel's Hospitality Management, Culinary Arts, and Food Science program.

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