Some people find that, a few hours after eating asparagus, their urine takes on an unpleasant sulphurous smell. Others appear unaware of this phenomenon, have never smelled the odor and are often express surprise when asked about it. For many years it was assumed that this was the result of a difference in asparagus metabolism: so that some people expelled the foul smelling chemical in their urine and others did not. Indeed, some people do not appear to produce the chemical (http://www.ncbi.nlm.nih.gov/pubmed/3569485), but the reason for this is not yet known. More recently, it was found that a greater proportion of people are unable to detect the sulphurous smell in urine, even though they are likely to produce the chemical (PMID:6584373) (http://www.ncbi.nlm.nih.gov/pubmed/20876394). Since most people are not in the habit of smelling other people’s urine, they would never be aware of the ‘asparagus pee’ phenomenon!
Can smell, Can't smell, Why would I smell my pee?
Text courtesy of the In Your Genome project: https://github.com/wtsi-hgi/IYG
