Why Asparagus Makes Pee Smell

Everyone’s pee smells like asparagus after they digest it. Deny this all you like, but those green stalks contain something called asparagusic acid, among a couple other compounds, that gives urine that unique odor.

As your body digests food, it breaks down different compounds through the enzymatic process. In the case of asparagus, its compounds are volatile and released as a vapor through the urine. That’s the aroma you smell when the compound exits your body, according to HuffPost’s conversation with Dr. Anish Sheth, a gastroenterologist at Princeton Medical Group and author of What’s Your Baby’s Poo Telling You?.

If you insist you’ve never before smelled what’s been informally dubbed “asparagus pee,” it’s because you lack the ability to detect the odor. The smell is there, you just can’t smell it. “The digestive process is pretty constant from person to person, but a person’s ability to detect these odors varies,” Sheth says. This is because our perception of smell — just like our perception of color — is completely personal. “We all have our own idiosyncratic smell perception of the world,” Dr. Ian Davison, a biology professor at Boston University, explains to HuffPost. “Our experience of different smells is completely unique.” The inability to smell this asparagus pee is an instance of specific anosmia, where a specific scent cannot be detected by a specific nose.

Leave a Comment