blog.sinden.org

I wrote this about four years ago in an email to herself, and it seems as relevant now as ever.

In 1891 a scientist named "Nencki" who, like me [immediately after graduating college], had so very little to do that he convinced four guys to eat seven kilograms of asparagus (that's about three and a half pounds each). He collected the pertinent pee, worked some "medieval magic" on it, and concluded that the smell was due to a metabolite called methanethiol.

So, this is just a smelly byproduct of digesting the asparagus that your kidneys dump into your bladder.

What is methanethiol (AKA mercaptan?), exactly? Methanethiol is composed mostly of sulfur with a little of hydrogen, and carbon (think rotten eggs). Merck warns that methanethiol may be a narcotic in high concentrations.

So, that's what makes your pee smell funny, but there is more to it than that.

Babe Ruth may have been the first person to bring this into the popular consciousness when he declined a plate of asparagus saying "asparagus makes my urine smell funny."

If legend is to be believed, only half of the people at the party laughed, and the other half didn't know what he was talking about. The assumption here is that there is a segment of the population that either does not produce methanethiol in large enough quantities OR for some reason, cannot smell it.

This second theory is propagated in a study by Lison et al. (1980) which relegates this phenomenon to the realm of smell hypersensitivity.

BUT other studies point to the varying production of methanethiol in different demographics. A study published in the May 1989 British Journal of Clinical Pharmacology found that 46% of 115 people tested produced the odor in one group of British citizens, while 100% of 103 people produced it in a group of French citizens, but this is no surprise, because we all know the French are smelly pacifists.

Just so you know, asparagus -- a member of the lily family along with garlic, onions, and leeks -- is a powerhouse of nutrients. It's an excellent source of folic acid (a B vitamin that may help protect against birth defects, heart disease, and cancer), a significant source of vitamin C (an antioxidant that may protect tissues against damage), and a good source of vitamin A (an antioxidant).

sources for this article: http://www.discovery.com/area/skinnyon/skinnyon970115/skinny1.html, http://www.zoo.ufl.edu/gpryor/austin.pee.html, http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=108390, and http://my.webmd.com/content/article/43/1671_51089.htm?lastselectedguid={5FE84E90-BC77-4056-A91C-9531713CA348}, all accessed June 2004.

Labels: food and drink, science and nature