The science behind the stink.  

By Corey Williams
April 01, 2019

You know what’s great? Asparagus. You know what’s not so great? Asparagus pee. If you’re part of the 20 to 40 percent of the population who reports pungent urine after eating the vegetable, you know what I’m talking about. But why does asparagus make your pee smell bad? Well, the answer is kinda complicated.

The History of Asparagus Pee

If you’ve ever eaten asparagus and then been grossed out by the smell of your own urine, you’re not alone—in fact, it’s a tale as old as time.

One of the first written mentions came from John Arbuthnot, Queen Anne’s doctor, in 1731.

Arbuthnot noted that the vegetable "affects the urine with a foetid smell...and therefore have been suspected by some physicians as not friendly to the kidneys."

Michelle Arnold / EyeEm/Getty Images

Benjamin Franklin later weighed in on the stinky subject, writing in 1781 that “a few stems of asparagus eaten, shall give our urine a disagreeable odour.”

But wait, there’s more:

French novelist Marcel Proust got characteristically literary with it when he wrote in 1913 that asparagus "transforms my chamber-pot into a flask of perfume," and a famous British men's club supposedly put up a sign that urged members “not to relieve themselves in the hat stand" during asparagus season.

Soooo, yeah. Don’t be embarrassed. You’re not the only one.

Why Does Asparagus Make Your Pee Smell Weird?

There’s been a lot of debate about what exactly causes the smell of asparagus pee, but scientists seem to have landed on asparagusic acid. During digestion, this acid is broken down into sulphur-containing compounds which tend to evaporate rather quickly. Like other sulphur-containing compounds, this results in a not-so-pleasant scent when it leaves your body.

Why Doesn’t Asparagus Make Your Pee Smell Weird?

Are you one of the lucky people whose urine isn’t affected by the vegetable? Well, I hate to break this to you, but your pee probably does stink after asparagus consumption—you just can’t smell it.

For years, people thought that only some unfortunate souls suffered from the smelly side effect. But, according to Mental Floss, a 1980 study revealed the truth: Everyone’s pee stinks after asparagus consumption, but some people lack the ability to smell it. Here’s how the researchers found out: Subjects who reported that their urine smelled funny after eating the vegetable were tasked with sniffing someone else’s pee—specifically, someone who claimed that their pee didn’t stink. You probably know where this is going: The pee stank.

Photo: Jeffery Cross

Apparently, some people have a gene mutation that affects their ability to detect certain scents. In this case, that scent is asparagus pee.

Can You Prevent Asparagus Pee?

If you can’t stand the smell of your pee after an asparagus binge, you’re not gonna like this: There’s nothing you can do to stop it. People have tried to conquer the stench, and those people have failed. Asparagus pee is just an unfortunate fact of life, it seems. You can expect to smell the effects 15-30 minutes after consumption, and it’ll likely last a few hours. Sorry.

Asparagus Recipes

Victor Protasio

If you’re (bizarrely) craving asparagus now, you’re in luck! We’ve got plenty of delicious asparagus recipes to choose from—just make sure to light a candle in the bathroom.

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