A lot of people love asparagus however, they notice something unusual after eating it. Eating asparagus can cause a rather unpleasant smell in urine.
Not everybody is an excretor of the odoriferous compound. And not everybody can perceive the odor, either. Both those traits are genetic.
What Causes It?
No one's really sure. We do know that the pungent chemical is some kind of sulfur based compound. But scientists have been trying to find the exact identity of it since the 1890s.
More recently, researchers found out that the smell is actually caused by a malodorous cocktail of six sulfur containing compounds. But that's what comes out after we eat asparagus, which is not necessarily the same was what went in. Our digestive systems do some pretty complex chemistry, you know.
Plus, the act of cooking the asparagus probably changes the chemistry around a bit, too.
So the next step was for scientists to find out what the chemical predecessor for this pernicious aroma is.
A number of different compounds have been tried, but the best results came from a molecule called asparagusic acid, which is thought to help the asparagus plant ward off predatory insects. Known excretors took this in pill form, and indeed the repugnant sulfur mixture came out the other end.
Researchers think that asparagusic acid or some derivative, probably bound in some form in the vegetable, is the likely candidate. But more studies need to be done to make absolutely sure.