The AFU and Urban Legend Archive
Food
Asparagus
 asparagus




From: eck@panix.com (Mark Eckenwiler)
Newsgroups: alt.folklore.urban
Subject: Re: Asparagus/smelly urine (not really UL, but I'm curious)
Date: 26 Apr 1996 13:40:09 -0400

[quoting from the Boston Globe, 6 June 1994 (Usha Lee McFarling's "How Why" column)]
>
> Asparagus is filled with sulfur-containing amino acids that
> break down during digestion into six sulfur-containing compounds.
> These can impart a unique smell to urine as they are excreted.
> "It's the same sulfur group that makes skunks smell," said Barbara
> Hodges, a dietician with Boston University's nutrition clinic,
> the Evans Nutrition Group.
>
> Scientists remain divided on why people have different urinary
> responses to eating asparagus. One camp thinks only about half
> of the population have a gene enabling us to break down the
> sulfurous amino acids in asparagus into their smellier components.
> Others think that everyone digests asparagus the same way, but
> only about half of us have a gene that enables us to smell the
> specific compounds formed in the digestion of asparagus.

>From the AFU crypt:

Newsgroups: alt.folklore.urban
From: jerry@jaizer (Jerry Gaiser N7PWF)
Subject: Re: What's it smell like?
Message-ID: <1991Jul12.161959.21689@intelhf.hf.intel.com> Organization: Intel Development Tools Operation, Hillsboro, OR Date: Fri, 12 Jul 91 16:19:59 GMT

In article <15231@dog.ee.lbl.gov> twcaps@tennyson.lbl.gov (Terry Chan) writes: >So, what's the story here? Cecil Adams notes that the origin of the
>compounds leading to the characteristic aroma is unclear but doesn't
>say anything about the ability to detect it being genetic. He does
>note that according to Allison and McWhirter in 1956, the ability to
>produce the odor is controlled by a single autosomal (non-sex-related)
>dominant gene which generates a compound called methanethiol. This would
>seem to imply that the problem lies in the ability to produce the smell,
>not detect it.
>
>On the other hand, Cecil also notes that work by Robert White at UCSD in
>1975 said rather the aroma was generated by several S-methyl thioesters
>but says that the metabolic origin of the compound is still an open
>question.
>
>Anybody got any better (e.g., clearer, more recent) results?
>
>

Ok .. Here goes ..

According to Harold McGee in "On Food and Cooking -- The Science and Lore of the Kitchen"

I quote

"From 1956 until 1980, it was thought that the excretion of odorous methyl mercaptan after eating asparagus was a dominant genetic trait; if you had the particular gene, you were a 'stinker.' But a recent study found that all asparagus eaters excrete methyl mercaptan; it is the ability to detect its odor that varies from person to person. The sulfur-containing amino acid methionine is suspected as the precursor in asparagus."

Jerry "Interjecting fact into AFU" Gaiser




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