Q. Why does eating asparagus make one’s urine smell funny?

A. Many people, but not all, produce the pungent and sulfurous smell shortly after ingesting even a few asparagus spears.

Recent research has narrowed down the chemicals involved and the inheritance path of the ability to detect the odor.

Several sulfur-rich candidates for the odor source have been proposed over the years, with a compound called methanethiol or methyl mercaptan being the most strongly represented in the urine.

As for the substance in asparagus that is metabolized to produce the odorant or odorants, recent studies have focused on one called asparagusic acid, or 1,2-dithiolane-4-carboxylic acid.