Adam’s Journal
My friend says that after he eats asparagus, his pee immediately has a distinctive odor. I, on the other hand, have never noticed any difference in the smell of my urine when I’ve consumed asparagus. Who’s the weird one here?
Dr. Scofield Prescribes
“A few stems of asparagus eaten,” said none other than Benjamin Franklin, “shall give our urine a disagreeable odour.”
In other words, at least according to our nation’s most-quoted Founding Father, you’re the weird one.
For an issue that has no health implications, “asparagus pee” has been the subject of a surprising number of scientific studies. But (and not surprisingly for an issue that has no health implications) those studies haven’t been terribly rigorous.
Your question actually turns out to be two questions. The first is whether everyone’s pee smells after eating asparagus. And the second is whether everyone can detect the distinctive odor.
On the first question – does everyone’s pee smell post-asparagus? – studies have produced widely varying answers.
The characteristic odor results from the breakdown of aspargusic acid to highly volatile sulfur compounds. However, people’s metabolisms differ, so we can produce different levels of these compounds in our urine.
In a 1989 study, researchers fed asparagus to 103 French people and reported that all produced stinky urine. Twenty-two years later, another team of scientists determined that 34 of 37 of asparagus eaters produced pee with detectable levels of the odor, which is variously described as something like skunk or rotten cabbage.
If you take these studies at face value, it seems that most of us are what researchers – who don’t like to use terms like “stinky pee factories” – call “excretors.”
In other words, you’re likely an excretor. If that’s the case, your good fortune in the restroom is probably tied to your inability to smell the offending odor.
How rare is that? According to the best study I could find (again, not a terribly high bar), not very: Roughly 3 in 5 people seem to have asparagus pee anosmia, the fancy word for an inability to detect a smell.
Scientific trivia to share with friends: Researchers linked this trait to at least 871 different genetic alterations.
To sum it up, most people appear to produce asparagus pee. A slight – lucky – majority can’t smell it. A large – unlucky – minority can.
So, getting back to your original question, neither of you are particularly weird. At least when it comes to this.
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Dr. Hal Scofield is a physician-scientist at the Oklahoma Medical Research Foundation, and he also serves as Associate Chief of Staff for Research at the Oklahoma City VA Medical Center. Adam Cohen is OMRF’s senior vice president and general counsel. Send your health questions to contact@omrf.org.
