Written by Ariane Lang, BSc, MBA top top December 23, 2019 — medically reviewed through Jillian Kubala, MS, RD, Nutrition

You may have actually noticed the after eating asparagus, her pee has a somewhat unpleasant scent.

You are watching: Does asparagus make your urine smell

This normally happens as result of the metabolism of asparagusic acid, and the ide is described as asparagus pee.

However, this specific side impact of eat asparagus doesn’t occur to everyone, and some may have never smelled such a thing.

This short article explains why eating asparagus renders pee smell, and also why just some human being can smell it.


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Asparagusic mountain is a sulfur-containing link that appears to be found exclusively in asparagus.

It’s a nontoxic substance that produces a sulfurous odor, which some say is similar to rotten cabbage.

Since a strong and pungent odor characterizes numerous sulfur-containing components, such as rotten eggs, organic gas, or skunk spray, scientists believe that asparagusic acid might be the cause of her pee’s funny odor after eating the vegetables (1, 2).

Summary

Asparagusic acid is a nontoxic, sulfur-containing compound that may reason your urine to have a distinctive odor after eat asparagus.


How does it affect urine smell?

Once her body metabolizes asparagusic acid, that produces numerous sulfurous byproducts the are extremely volatile — definition that castle vaporize conveniently (3).

When you pee, this compounds evaporate almost immediately, which enables them to take trip from the urine approximately your nose, enabling you to smell them.

Though scientists have actually not been able to recognize whether one compound is responsible for the odor or if it’s because of the mixture of every one of them, a compound dubbed methanethiol is widely pointed out in the literature.

Methanethiol, likewise known as methyl mercaptan, is characterized by a solid and unpleasant scent that’s often associated with fecal odor and also bad breath — and it happens to it is in the most common odorant found in to pee after eating asparagus (4, 5, 6).

How lengthy does the odor last?

Some people an alert the rotten-like odor as beforehand as 15–30 minute after eating asparagus, and studies have determined that in ~ 25 minutes, half of the asparagusic acid consumed has already been soaked up (7).

The rapid absorption rate suggests that the effect of asparagus ~ above urine odor can appear quite quickly, and also recent studies also agree that it deserve to last for much more than a few hours.

One study in 87 people who ate 3–9 spears the asparagus found that the half-life the the asparagus smell was 4–5 hours (3).

The half-life of a substance tells you exactly how long it takes for it to reduce to half of its initial amount. Therefore, if the half-life that the asparagus odor was estimated at 4–5 hours, it method that the total effect might last approximately 8–10 hours.

Yet, another study in 139 people who also consumed 3–9 asparagus spears reported the half-life the the odor to be 7 hours, an interpretation that the effect might even last approximately 14 hours (7).

Either way, you can expect her pee to odor for rather a while.

Summary

When your body metabolizes asparagusic acid, it produces numerous smelly, sulfur-based compounds that offer your pee a rotten-like smell that deserve to last 8–14 hours.


The result of asparagus top top urine odor is no universal, and also a number of hypotheses try to describe this phenomenon.

One hypothesis — called the manufacturing hypothesis — says that just some individuals are capable of producing the sulfurous compounds responsible for the smell, when others space non-producers.

This hypothesis asserts the non-producers lack a key enzyme the helps metabolize asparagusic acid and are hence unable to produce the smelly byproducts (4).

For example, a tiny study in 38 adults established that around 8% the them one of two people didn’t develop the smell or developed it in ~ concentrations the were too low to it is in detected (4).

The various other hypothesis — called the perception hypothesis — claims that everyone produces the smell, but some are unable come detect or perceive the (4).

In this case, researchers uncovered a genetic change that alters one or an ext of the olfactory receptor that have to respond come the asparagus smell, leading to what is known as asparagus anosmia, or the inability to odor asparagus to pee (8).

In fact, research says that a large percentage of human being can’t smell asparagus pee.

One study in 6,909 adults provided that 58% of men and 62% that women had asparagus anosmia, arguing that this particular genetic alteration is quite common (8).

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Summary

Not anyone is acquainted with asparagus pee, and also researchers think that it’s because some civilization either don’t create the smell or space unable to perceive it.