Asparagus urine: Why only half notice the smell!

Asparagus urine: Why only half notice the smell!

With the start of the asparagus season, many people experience a phenomenon that is constantly a topic of conversation: the characteristic smell of “asparagus urine”. This unpleasant smell usually occurs a few minutes after eating asparagus and is the result of a biochemical degradation process that takes place in our body. The main culprit is aspartic acid, which is found in asparagus and is converted into sulfur-containing compounds through a series of enzymatic reactions. These controversial substances, such as methanethiol, dimethyl sulfide and dimethyl sulfoxide, enter the urine via the kidneys and produce the typical smell that is reminiscent of rotten vegetables.

It is noteworthy that not every person notices this smell. According to oe24.at, around 40 to 50 percent of people have a special enzyme that converts aspartic acid into odor-intensive compounds. The remaining people either do not release this acid or only release it minimally. In addition, there are people who do not notice these smells at all due to a genetic predisposition known as specific anosmia. This anosmia can be caused by a defective olfactory receptor gene, such as OR2M7.

Genetics and perception of smell

A comprehensive study of nearly 7,000 participants showed that 58 percent of men and 61.5 percent of women notice little or no smell after eating asparagus. These differences in perception are genetically determined and are related to varying genes near olfactory receptor genes, as tagesschau.de reports. However, it remains unclear whether these people do not produce the chemical compounds or are simply less sensitive to them. The results of these studies relate only to European populations, which limits generalizability to other ethnic groups.

What is also interesting is the fact that the sulfur compounds produced from asparagus are considered harmless to health. They usually disappear from the body within a few hours. Laborpraxis notes that the smell is not a sign of an underlying illness or intolerance. However, the substances contained could be due to a higher content of vitamins and minerals traditionally associated with asparagus.

The perfect asparagus

The asparagus season in Germany extends from April to June, when fresh asparagus is harvested. There are different varieties, such as white asparagus, which is harvested underground, purple and green asparagus, which is harvested above the ground, and the classic green asparagus, which grows in the air. Fresh asparagus is characterized by firm, closed heads and plump, moist spears. In addition to being delicious, asparagus is also known for its high content of vitamins such as A, B1, B6, C and E as well as minerals such as iron, calcium and magnesium.

Although the perception of the smell of asparagus can vary greatly, there are currently no known measures to completely prevent this smell. The first approaches to reduction are in research, but ventilation currently remains the simplest solution for those affected.