Fun food fact of the week: Why asparagus makes urine smell funny

asparagus
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Spring has finally sprung in Berkeley, and with it comes an exciting array of spring produce, including asparagus. While to some this means delicious asparagus risotto, grilled asparagus and creamy asparagus soup, to others it signifies the return of the dreaded asparagus pee.

If you’ve kept your concern about curious-smelling urine after eating asparagus a secret all this time, do not be alarmed — you are not alone. A funky odor in your pee is a natural biological phenomenon, and although it may not be the most savory topic, asparagus urine is certainly something many of us have dealt with. What causes this bizarre odor?

Asparagus contains a high concentration of a sulfur-containing compound called asparagusic acid, named for the vegetable, of course, which can also be found in other pungent-smelling foods such as rotten eggs, onions and garlic. When your digestive system breaks down asparagusic acid, it releases volatile odoriferous components that are the culprits of the strange smell associated with asparagus urine. This process is so quick that the distinctive smell can develop within 15 to 30 minutes of eating asparagus, which can lead to unfortunate social circumstances such as awkward dinner-party bathroom breaks and avoidance of all beverages when asparagus is on the menu.

However, the asparagus pee phenomenon does not affect all asparagus-eaters equally (though this is not an excuse to deny that you were the one who left a strange-smelling aroma in the bathroom). As asparagus pee is such a hot topic in the both the scientific and culinary world, there have been various studies regarding it, and apparently between 22 percent and 50 percent of the population report having pungent urine after eating the vegetable in question.

So why isn’t the other 50 percent to 78 percent of the population familiar with the acrid stench of asparagus pee? There are two schools of thought on this issue. One is that only certain people’s digestive systems work in such a way that breaks down the asparagusic acid to release the sulfurous compounds. Therefore, certain people simply do not have the metabolic ability to create asparagus urine.

The other school of thought regarding asparagus’ odoriferous effects on urination is that the DNA code-associated nasal receptors that detect the specific compounds created by asparagus urine only exist in some people. In this case, all humans produce funny-smelling pee after ingesting asparagus, but only certain individuals with a particularly sharp sense of smell can (unfortunately) detect the odor. In other words, while all of us have the ability to produce volatile-smelling urine, only some of us have keen enough noses to suffer from the results.

Sadly, it is is not currently the No. 1 priority of food scientists to nail down the exact DNA sequence that codes for either the ability to metabolize asparagus into sulfurous compounds or the sequence that allows us to smell said compounds. So until researchers are able identify this variation in your genome and subsequently alter the DNA sequence to desensitize you to the pungent aroma produced by eating this delicious spring vegetable, you’re stuck with smelling asparagus urine for the rest of your life.

Since this is the case, I say that the 22 percent to 50 percent of us who cringe at the thought of the alarming smell of asparagus pee should no longer hide in fear. Now that the elephant in the room has been addressed, you should not be ashamed to release those volatile sulfurous compounds after savoring a delicious side of asparagus to accompany your springtime supper. Asparagus is only in season for a few short months out of the year, so don’t let the fear of producing asparagus pee hamper your enjoyment of this tasty vegetable. Instead, celebrate your genetic gift, and cross your fingers that the person who uses the bathroom next lacks the ability to smell asparagus urine.

Contact Erika Chan at [email protected].

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  • Tonia Addison-Hall

    I’m allergic to sulfa and I have asparagus pee.

  • Tim Anderson

    Great article…it’s asparagus season right now and I love it, but it is quite a nose turner.