Re: how after eating asparagus does your urine smell so quickly. and what is th

Hi there

Well that's an odd question! Though perhaps not for those of you out there who love eating Asparagus. I however, have never been fond of it - so have never encountered this phenomenon.

Anyway - interested as I was about the answer - I did some delving and found a website created by the Michigan Asparagus Advisory Board (...I know, I was amazed too!) who seemed to offer an answer:

So why does urine smell funny after consuming asparagus?
Most authorities feel that the compound that causes the odour in urine after consumption of asparagus is methylmercaptan, which is a sulphur- containing derivative of the amino acid, methionine. This is disputed by a few individuals who claim that the odiferous compound is asparagine-amino- succinic-acid monoamide, which is derived from the amino acid, asparagine. In either case, the product is formed as a derivative during the digestion and subsequent breakdown of beneficial amino acids that occur naturally in asparagus.
Ref: Merck Index, 862; Food Chemistry, Belitz and Grosch, pg. 271.

As for why the smell appears so quickly, all I could suggest is the following:

The products chemicals implicated in urine odour [methylmercaptan or asparagine-amino-succinic-acid monoamide] are products formed as a derivative during the digestion and subsequent breakdown of beneficial amino acids (methionine & asparagine, respectively), which occur naturally in asparagus.

These compounds can be potentially harmful in large concentrations (particularly methylmercaptan), and I suggest that their removal from the body is just a simple demonstration of kidney function. The fact that urine can develop odour within 15 minutes of consumption suggests that these derivatives are good markers demonstrating just how fast the kidneys can eliminate such compounds - which you ordinarily wouldn't notice without a distinctive odour or colour.

So there you have it!

Jamie Caryl
MAD Scientist