Why Does Asparagus Make Your Pee Smell?

And if you haven't smelt it, it doesn't necessarily mean you haven't dealt it. 

Asparagus is a favorite springtime side dish but, unfortunately for many of us, smelly urine is an inevitable byproduct of eating asparagus. As French novelist Marcel Proust colorfully put it in 1913, asparagus, "transforms my chamber-pot into a flask of perfume."

If you're feeling embarrassed about the way your pee smells — don't be. It happens to many of us. And the reason for it is a question scientists have been grappling with for centuries. It's time to learn the why and the how behind asparagus pee.

Why Does Asparagus Make Your Pee Smell?

The reason for asparagus pee lies with a compound known as asparagusic acid, which (as far as we know) is found exclusively in asparagus. When your body metabolizes this compound, it produces several sulfurous byproducts.

These byproducts are highly volatile, meaning they evaporate immediately, allowing them to quickly travel from the urine all the way up to your nose...which is why you can immediately smell them. The odor can be detected as soon as 15 minutes after eating asparagus.

Scientists haven't quite been able to nail down which compound it is that creates the smell, or if it's a combination of all of them, but methanethiol is a prime suspect because of its bad smell that's associated with fecal odor and even bad breath.

asparagus spears stacked on top of each other with water droplets
Karla Conrad/Meredith

Does Everyone's Pee Smell After Asparagus?

For much of my life, I thought asparagus pee was an extremely rare (and embarrassing) inconvenience that affected an unlucky few. But it turns out, between 20 and 50 percent of people experience it (depending on the study you look at). There are two hypotheses as to why a person might not experience asparagus pee:

  1. You might be able to break down sulfur byproducts more efficiently, making you a "non-producer."
  2. You might not be able to smell your own asparagus pee. This hypothesis, which is growing in popularity, suggests that certain gene variants may prevent people from being able to detect the asparagus pee smell. A small 2010 study concluded that there are differences among individuals in both their ability to procure and detect the smell.

What Does Asparagus Urine Smell Like?

I've struggled to describe the smell of asparagus pee to those lucky enough never to have smelled it, but it's commonly referred to as a "rotten," smell. More specifically, it's been described as smelling like rotten cabbage...so, not great.

How Long Does Asparagus Make Your Pee Smell?

We've already established that asparagus can make your pee smell as soon as 15 minutes after consumption, but how long can these effects last? There's nothing like being reminded that you ate asparagus hours later, or even the next day...

The good news is, it appears the effects subside with time. One study found the half-life (the amount of time it takes for the smell to reduce by 50 percent) of asparagus smell in urine to be 7.2 hours, meaning the effects can last for over to 14 hours.

How to Get Rid of Smelly Urine After Eating Asparagus?

Not to be the bearer of bad news, but there's very little that can be done to prevent and/or stop that lovely asparagus pee smell. The only way to prevent asparagus pee is to not eat it (and we don't recommend that).

Though it won't eliminate the smell entirely, drinking more water can dilute it. But the bottom line is: If you want to enjoy asparagus, you have to embrace the bathroom stall stench.


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