Why do some people smell a strange odor in their urine after eating asparagus and others don’t? Which substance is responsible for this.

After eating asparagus, our body produces sulfur-containing decomposition substances that are responsible for the odor in the urine. The smell itself is therefore not in the asparagus. First we have to digest the asparagus and make certain breakdown substances (metabolites) with it, which are excreted in the urine. It is not known exactly which degradation substances are correct, but they may be thiols or thioesters. Due to gene polymorphism (hereditary differences, but the correct genes involved in this are still unknown) people differ in their sensitivity to smell this odor in the urine. People who don’t smell these substances in their urine will probably smell them anyway at higher concentrations (or when they hold their nose close to the urine!).

There are other examples of chemicals that are perceived by some people and not others through the nose, or for which the sensitivity differs, and which are explained by genetic differences between the people.