Why Does Asparagus Make Your Pee Smell Funny?


Asparagus season is in full throttle. In our home, we indulge in these delectable stalks of spring several times a week, usually tossed with a bit of olive oil and Kosher salt and then roasted. Indelicate or not, at some point our conversation turns to asparagus pee or Post-Asparagus-Stinky-Urine Disorder (PASUD).

Marcel Proust wrote in Swann’s Way, that asparagus had the effect of transforming his “humble chamber pot into a bower of aromatic perfumes.” Perhaps one should credit his affinity for absinthe for his appreciation of said perfume. Proust aside, most folks find the aroma just plain stinky. I always believed the stinky pee was due to my body’s breaking down all the nutritive benefits of asparagus better than those who never detected the odor. Assuming this disorder had a simple scientific explanation, I turned to the internet for the skinny. Does everyone’s pee smell or do some people have more heightened olfactory senses? Asparagus contains asparagusic acid; as our bodies digest asparagus, its compounds are released as a vapor in our urine. Some researchers believe everyone’s urine releases the odor, but some people just can’t smell it. We all have different olfactory sensors. Other researchers claim two compound found in asparagus, S-methyl thioacrylate and S-methyl 3-(methylthio) thiopropionate, are unable to be digested by some people and yield the stinky pee.

Whatever the cause or the outcome, I will continue to indulge in my favorite vegetable until the end of its season. Don’t disparage my asparagus.

This story was originally published in May 2015.