Asparagus is considered a delicacy in western culture, often eaten in high esteem with eggs or salmon.  As a vegetable, asparagus is a good source of vitamin K, zinc, iron and folate; however, one downside it can produce offensive odorous urine. The first documentation of this odour has been traced back to 1702, however, humans have been eating asparagus for thousands of years.

The ability to detect the ‘I ate asparagus last night’ urine smell does not occur in everyone. The odorous sulphur smell is not linked to the kidney’s ability to process asparagus metabolites, in fact, the smell is linked to the olfactory system (smell receptors) in our nose. This comes down to genetics, with two in five people having DNA variations within their olfactory system giving them the ability to detect this smell. Lucky them!

A large study with 7,000 people showed that 40% of participants strongly agreed they could smell the sulphur odour, whereas 60% could not. Interesting the ability to detect this smell was higher in men than women. This may or may not be related to the difference in positioning between the two sexes during urination. In relation the male versus female phenonium, there are some debates in this world that science doesn’t have the answers too and this is one. Science is definite through that the ability to detect the post-asparagus urine smell is related to genetics.

Alyce Rees – Accredited Practising Dietitian/ Personal Trainer

Food in Action – Dolphins Health Precinct, Redcliffe

Phone: 07 3880 3729

Email: [email protected]


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