Study identifies why some people can smell asparagus in urine:
"In The BMJ's Christmas edition this week, a study identifies the genetic origin of the ability to smell the strong, characteristic odor in human urine produced after eating asparagus.
A team of U.S. and European researchers found hundreds of variants in the DNA sequence across multiple genes involved in sense of smell that are strongly associated with the ability to detect asparagus metabolites in urine.
...Asparagus is considered a delicacy, but it's also known to produce a distinctive odor in urine.
Not everyone can detect the odour of metabolites (methanethiol and S-methyl thioesters) produced by consumption of asparagus.
...Findings show that 40% (2,748/6,909) of participants agreed that they could smell a distinct odor in their urine after eating asparagus, and 60% (4,161/6,909) said they could not and were labelled as 'asparagus anosmic'.
The researchers linked information from genome wide association studies on over 9 million genetic variants with the asparagus anosmia trait.
They discovered 871 particular variations in DNA sequence, known as single nucleotide polymorphisms, on chromosome 1 which were associated with being asparagus anosmic. These genetic variants were found in several different genes responsible for sense of smell.
They also found that a higher proportion of women reported they were unable to detect the odor, compared to men, despite women being known to more accurately and consistently identify smells..."