Shannon Dininny / AP
Tasty asparagus can have the surprising effect of leaving a distinct aroma in the urine of an unwary diner. Scientists have spent years figuring out why that's so.
Many of you -- maybe three-quarters of our readers here -- are about to learn a small bathroom secret that the rest of us rarely, if ever, mention.
Sometimes our pee smells funny.
Specifically, after eating asparagus, about one in five people detects a distinct scent in their urine that, depending on the person, carries a pungent bouquet that’s been compared to a vegetable garden, sulfur, cabbage soup -- or simply cooked asparagus.
Some folks don’t speak of it, possibly thinking they are utterly alone in this weird wing of the whiz world. (They are not).
Some folks, like 38-year-old Kathleen Lisson of Troy, N.Y., are bold enough to openly share their asparagus pee play-by-play.
“I smell asparagus in my urine after eating asparagus, especially freshly grilled asparagus,” says Lisson, an event planner. “I had always just assumed it was because my body did not digest the chemical compound that gives asparagus its smell. I always smile and giggle a little bit when I visit the restroom a few hours after eating asparagus. The smell reminds me to not take life so seriously.”
Lisson is correct about chemicals causing the aromatic effect. In 1975, California chemist R.H. White used a lab process called gas chromatography-mass spectrometry to analyze urine supplied by 115 people after asparagus consumption. White learned that when humans digest 100 grams of the vegetable, their urine soon contains 2 milligrams to 5 milligrams of two specific chemical compounds (S-methyl thioacrylate and S-methyl 3-thiopropionate) and these “appear to be the odor-causing compounds.” His findings later were published in Science magazine.
The social consequences of the asparagus aroma can be funny, as Alyssa Phillips, an Atlanta physician's assistant with a degree in nutrition recalls. When she and her husband, Neil, were first dating, she made him fresh asparagus for dinner. After the meal, he headed for the bathroom -- and then emerged asking if Phillips was feeling OK.
"When he peed and smelled the foul odor, he assumed his sweet, new girlfriend might have passed something along," says Phillips.
That “hilarious conversation,” along with Phillips’ passion for nutrition, caused her, she says, to further research the phenomenon. Phillips learned that “all humans appear to produce the smelly compound, but only some humans -- 22 percent -- have the ability to detect the smell.”
Indeed, a 1994 book titled “The RE/Search Guide to Bodily Fluids,” by Paul Spinrad, cites that 22 percent stat and reports that it was calculated through a survey of asparagus eaters.
Now it's official: the other 78 percent of you are privy to our private pee party.
Scientists also theorize that we who notice the aroma carry a little something extra in our DNA that boosts our sense of that scent. The rest of you, well, let’s just call you smell-blind.
“We believe that the mystery behind asparagus detection in urine is genetic,” says Dr. Walter Gaman, a family practice physician and a partner at Executive Medicine of Texas, a clinic northwest of Dallas.
And before you write this topic off as simply more yellow journalism, be aware that asparagus pee colored several pages of one of the greatest works of modern literature: “Love in the Time of Cholera,” by Gabriel García Márquez.
As the author wrote in one passage: “Even when it was not the season for asparagus, it had to be found regardless of cost so that he could take pleasure in the vapors of his own fragrant urine.”
Clearly, García Márquez is part of the 22 percent club.
More from The Body Odd:
First published June 29 2012, 5:43 AM