Why Asparagus Makes Your Urine Smell

Ever wonder why your pee smells funny after eating asparagus? You’re not alone. For decades, curious minds have pondered the topic of “asparagus pee.” Fortunately, researchers have answers for this age-old question.

A Problem Throughout History

The Scottish mathematician and physician John Arbuthnot wrote in a 1731 book that, “asparagus… affects the urine with a foetid smell.” (An archaic form of the word fetid meaning, “having an offensive odor; stinking”) French novelist Marcel Proust wrote in 1913 that asparagus “transforms my chamber-pot into a flask of perfume.” Even the brilliant inventor and statesman, Benjamin Franklin, wrote in a 1781 letter to the Royal Academy of Brussels that, “A few stems of asparagus eaten, shall give our urine a disagreeable odour.”

Finding Answers Through Research

Modern day researchers are making great strides in finding answers. The culprit of the funky smelling urine appears to be asparagusic acid, a compound high in sulfur and abundant in asparagus. When your body digests asparagus and breaks down asparagusic acid, it releases volatile components that are responsible for the foul smell of asparagus urine. This smell can develop within 15-30 minutes of eating asparagus.

Interestingly, asparagus does not affect all asparagus eaters in the same way. Studies indicate between 22-50 percent of people report having strange smelling urine after eating asparagus. So what about the other 50-78 percent of the population? Why don’t they smell anything after eating asparagus?

Researchers have put forth two fascinating theories:

• Some people’s digestive systems can break down the asparagusic acid to release the sulfurous compound. The rest of us don’t have the metabolic ability to produce pungent asparagus urine.
• The DNA code-associated nasal receptors that detect the specific compounds created by asparagus urine only exist in some people. So this theory states all humans produce smelly urine after eating asparagus, but only certain people are able to smell it.

Unfortunately, research regarding asparagus pee isn’t on the top of the priority list for scientists, so we may be waiting a while to find out which theory is true.

In the meantime, don’t let that stop you from eating asparagus. This delectable veggie is loaded with nutrients and antioxidants that are healthy for your body… even if it isn’t pleasing to the nose.