Why Does Asparagus Make Your Pee Smell?

The science behind why this weird effect happens
eating asparagus

Ever wonder why eating asparagus can lead to funky smelling pee? If so, you’re not alone.

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Although asparagus pee might not be a top priority for scientific research, it’s been observed and wondered about for long enough that it has warranted some investigation.

In this article, nephrologist Shane Bobart, MD, explains why the asparagus pee phenomenon happens, who it affects and if there’s anything you can really do to prevent it. 

What causes the smell?

The main culprit is aspargusic acid, which is found exclusively in asparagus. When asparagus is digested, asparagusic acid gets broken down into sulfur containing byproducts. Sulfur, in general, is not very pleasant to smell, notes Dr. Bobart. When you pee, the sulfur byproducts evaporate almost immediately, causing you to smell that unpleasant scent.

It’s worth noting that asparagus isn’t the only thing that can change the smell of your pee. Other foods and drinks have been known to cause smelly urine. For example, some people report that drinking too much coffee causes their urine to smell like coffee. Brussels sprouts, onions and garlic have also been linked to odd smelling pee in some people.

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Asparagus pee usually shows up between 15 and 30 minutes after eating the vegetable and can last for several hours. One study found that the smell could last for up to 14 hours!

Is it normal?

Asparagus urine odor has been observed for centuries. So before you start wondering if something is wrong with you, rest assured asparagus pee is a totally normal bodily reaction.

Depending on what study you read, it’s estimated that between 20% to 50% of people experience it. For those who don’t get to encounter the joy of asparagus pee, researchers believe the reason might be two-fold:

  1. Everyone digests food differently and some people can break down the sulfur byproducts more efficiently.
  2. Some people lack the ability to detect the odor simply because of genetic variations.  

Everyone metabolizes food compounds differently. Some people have never smelled asparagus pee before simply because that’s how their body works.  

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Don’t stop eating asparagus because of it

Urine is your body’s way of filtering out waste through your kidneys. Just because your pee might stink after eating asparagus doesn’t mean you should ditch the stalky vegetable.

“Asparagus is considered a low-potassium food in small portions,” says Dr. Bobart. “It can be eaten as part of a healthy diet and will not harm your kidneys.” Those with kidney disease are encouraged to eat a low-potassium diet, so asparagus (six stalks or less) is a great addition.

Unfortunately, there’s nothing you can do to prevent asparagus pee from happening to you. At the end of the day, it isn’t a big deal and it happens to many of us. So don’t shy away from asparagus because of urine odor. In fact, next time you smell that distinct scent, go ahead and pat yourself on the back for choosing a nutritious veggie – think of it as a smell of success!  

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