Asparagus and That Stinky Smell

One of my favorite vegetables is asparagus. I love it because it is easy to cook and tastes delicious. It looks fun and can even serve as a "fancy" side dish for a nice dinner. It is a pretty green color and contains lots of vitamins and minerals that are good for your body. But what happens after you enjoy your asparagus with dinner? Have you ever noticed that terrible smell when you urinate? It is terrible! It is almost stinky enough that it might make you reconsider enjoying asparagus, as a vegetable at your next meal. 


So why does that happen? How does it work? I have asked this of myself every time I cook, eat and urinate after consuming asparagus.There is a compound that is only found in asparagus and they have called it asparagusic acid. This is a sulfur containing compound (mercaptan), which explains that terrible odor that occurs in your urine after eating asparagus. Mercaptan is also found in rotten eggs, onions and garlic. It is thought about 22-50% of people are able to smell this compound.

This asparagusic acid compound is "volatile." That does not mean it will explode, but it means that the compound is easily airborne and floats up to your nose very quickly. This means that you can perceive this odor within 15 minutes of eating asparagus spears.

This has prompted the debt about if some people's body produce asparagusic acid compared with the idea that maybe your nose can not smell this compound. After some studies in the 1980s in France and Israel, found that the difference is in the perception of the this asparagusic odor compared with production on this compound. So it is thought that everyone produces this compound, but not all of us came smell it. So some people might not have the olfactory sensors to perceive this sulfur-like smell. They have some genetic mutation that prevents them from smelling this odor. A study was done, by a researcher at Harvard, that included 7,000 participated and out of that group 40% could smell that "stinky odor" after eating asparagus. That left 4,161 who were unable to smell that asparagusic acid. They contribute that inability to smell that compound to some combination of a possible 871 gene variations affecting that sensitivity in the nose. 

So in the end there isn't a clear reason why people can or can't perceive that terrible stink after eating asparagus. There is even doubt on the exact type of compound that makes that distinct odor. In the end, they main take away is ... don't be surprised if you enjoy your asparagus and then have a stinky pee afterwards. You are not weird, that is normal, for ~40% of people. 


  1. Why Asparagus Makes Your Urine Smell. 
  2. Why Your Pee Smells Funny After Eating Asparagus.
  3. Why Asparagus Makes Urine Smell. 
  4. We Unravel The Science Mysteries of Asparagus Pee.