Asparagus and Olfaction
Nutrition January 20th. 2008, 9:29pm
It was not that long ago that one of my college buddies mentioned to me that asparagus makes your urine smell bad. Apparently this fact is rather widely disseminated among young adults (adolescents rarely partake of the vegetable out of childish aversion), and although I do eat, and enjoy, asparagus, I was uninformed, obviously uninformed, of the urine bit. As I prepared some asparagus for this evening’s dinner, I decided to look into the phenomenon.
This notion of noisomeness associated with asparagus was first documented in the 1730s, despite the food’s longstanding culinary presence. It was not until the 20th century, however, that scientists investigated it. Although, I suppose that malodorous urine was no reason to keep a scientist up at night, considering that they did not yet realize that living organisms are made of cells, nor that infection is caused by germs. In any case, as far as I can tell, scientists first began to probe the issue in the 1950s. For the next 30-some years, it appears that they concluded, incorrectly, that around 50% of individuals produce the unpleasant stench as a result of eating asparagus. Interestingly, these assertions were tainted with bad science: the studies did not implement an objective means of determining whether or not the foul smell occurred (they relied on the report of the individuals who ate the stuff).
Here’s the punchline: while a fraction of individuals may excrete the actual chemicals associated with the stink (thiols and thioesters — sulfur-containing compounds), only a fraction of people can actually smell the putrid result. The observation is, therefore, doubly confounded by the ability to excrete noxious urine and a genetically-based anosmia, which up to 90% of men and women may have. (1)
So we can really only conclude one thing from this discussion: if you eat asparagus, and you think your urine subsequently smells bad, then you’re right … it does, and you’re a “producer.” If you smell nothing, however, you may or may not be an offender. Eat warily, mes amis.
January 21st, 2008 at 6:35 pm
Dear Sir,
Thank you kindly for your illuminating exploration of our marvelous body’s ability to transform common asparagus into malodorous urine. I found it intriguing, especially since I am able to both produce and smell that nasty concoction that I refer to as “pee pee stinky stink.”
I hope that you will entertain a few suggestions for future related pieces. First, I notice that in addition to my thioester-infused urine, about 98% of my feces also smells, occasionally so bad that my small apartment must be vacated for hours. Is this consistent with the rest of the population? Are there individuals who are unable to produce smelly poop or who are unable to smell nature’s nasty elixir that wafts from fecal matter? I am dying to know.
Second, do females “do number 2?” I am convinced that they do not, but one time I accidently wandered into a female restroom and heard what sounded like someone pooping. That day still haunts me. Perhaps it was a man whose personal matters were too urgent to make it to the more distant male bathroom? Could it really have been a member of the fairer sex?
I would appreciate your insights on these topics.
Fondly,
-Another who cares deeply about the body’s mysteries