The food you put in your mouth always affects what comes out the other end. But we're not just talking about spicy butt from hot wings or explosive hangover diarrhea. Food affects your pee, too—and asparagus is one of the most notorious culprits.
Asparagus is super healthy and packed with fiber and vitamins. The downside? It makes your urine smell nasty, like rotten eggs. Well, at least for some people.
Asparagus taints your pee with a weird type of acid that only certain people can detect. If you're reading this, chances are you're in that camp.
Read on to learn why asparagus makes your pee smell funny, the genetic factors at play, and how long you can expect this strange scent to stay in your system.
Why Does Asparagus Make Your Pee Smell Weird?
Asparagus contains "asparagusic acid," a chemical compound only found in asparagus. There's a lengthy Wikipedia article dedicated to this topic, but we'll keep things simple: When you digest asparagusic acid, it releases a bunch of sulfur-containing compounds and metabolites that evaporate when you take a leak.
As you pee, these sulfur byproducts waft up to your nose. There's a distinct odor that has been compared to rotten eggs, cooked cabbage, vinegar, and skunk spray. Scientists believe the main culprit is methanethiol, a colorless gas that you can blame for the smell of poop and bad breath. Warning: this stuff is highly flammable.
The first documented instance of asparagus urine dates back to 1702 when a French botanist named Louis Lémery said that "asparagus...affects the urine with a fetid smell." Marcel Proust offered a more colorful description, writing that asparagus "transforms my chamber-pot into a flask of perfume."
Benjamin Franklin also took note of the phenomenon in his book Fart Proudly (yes, it's real), saying that "a few stems of asparagus eaten shall give our urine a disagreeable odor."
How Long Does Asparagus Make Your Pee Smell?
After eating asparagus, you may notice your pee starting to smell weird within 15-30 minutes. This effect usually lasts 4-5 hours.
The first ever study about asparagus pee observed 87 people who ate 3-9 spears of asparagus. Most participants reported a "clearly present" odor in their urine that lasted almost five hours.
The researchers noted that the half-life of the asparagus effect on stinky pee was 4.7 hours. That means the total effect could last up to 10 hours.
Bottom line: if you're nervous about having smelly urine, swap asparagus for another veggie.
Does Everyone's Pee Smell From Asparagus?
It's unclear whether everyone's pee smells from asparagus, but the science community's educated guess is "no." A small study from 2011 determined that 8% of participants didn't have smelly urine after eating asparagus.
The theory here is that certain people don't have the digestive enzyme that metabolizes asparagusic acid. Therefore, they don't produce the smell.
Can All People Smell 'Asparagus Pee?'
Nope, here's where things get interesting. It's estimated that less than half of people can detect the smell of asparagus pee. Researchers suspect this is because of genetic variations that change our olfactory receptors.
There's even a name for the inability to smell asparagus pee: "asparagus anosmia."
This 2016 study determined that 62% of women and 58% of dudes had asparagus anosmia. So, if you catch a whiff of this unpleasant aroma, you're in exclusive company. Congrats, dude.
How to Neutralize Asparagus Pee
Asparagus pee is normal, so don't freak out and think your insides are rotting. But as Ben Franklin noted, the smell is pretty brutal. This leads to an important question: can you cancel out the odor from asparagus pee?
Indiana University Health suggests that drinking water and cranberry juice can neutralize the sulfur compounds that are responsible for asparagus pee. However, your best bet is to just wait it out.
If your pee doesn't smell normal within 48 hours, that could be a red flag.
"Foul smelling urine could indicate other more serious conditions, such as a urinary tract infection or liver disease," says Amy Krambeck, M.D., a urologist at IU Health Methodist Hospital. "If the foul odor persists despite discontinuing the suspected food (aka asparagus) or if it is accompanied by other symptoms, seek medical advice."
Don't let asparagus pee turn you away from this veggie—the health benefits outweigh a few hours of an unpleasant odor. And unlike poop, the odor won't linger in the bathroom nearly as long.
Just be warned: asparagus is notorious for producing dumps that smell downright horrific, so make sure you're packing DUDE Bombs Toilet Spray to hide the evidence.
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