Why eating asparagus makes urine smell?« Back to Questions List

Asparagus is a spring vegetable.  Asparagus belongs to flowering perennial plant species. Asparagus was once classified in the lily family along with some other species like onion and garlic. Later on, said family was reclassified into two; onion like plants are now classified under Amaryllidaceae  while asparagus comes under Asparagaceae.

People often feel a strange smell for their urine after they have consumed asparagus. Asparagus contains the amino acid asparagine which consists of sulphur compounds. Normally, the smell is mild. Sometimes, the enzymes in the stomach break down the sulphur compounds causing presence of different compounds of sulphur in urine. Biochemists have identified  presence of upto six different sulphur compounds in urine. 

The enzyme need not be present in the stomach of everybody. This characteristic is mainly an inherited trait. The chances of having the enzyme present in children cannot be ruled out,  even if  only one of the parents has the trait. Researchers are yet to identify the gene that causes presence of enzyme. 

It is also interesting to note that the distinctive smell is perceived only by some people. It is estimated that only 10% of the population has the extra degree of sensitivity to identify the smell. In short, even if some people produce the distinctive smell, they do not identify the smell. 
 

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