Monday, March 05, 2018

What’s that smell?

In this week’s newsletter from World’s Healthiest Foods we find out what that strange odor is from urine after eating asparagus.

“One of the unique phytonutrients in asparagus is asparagusic acid. Asparagusic acid is the compound responsible for the urine odor that many people associated with asparagus. In chemical terms, asparagus acid (1,2-dithiolane-4-carboxylic acid) is unusually reactive due to the two sulfur atoms that are positioned adjacent to each other in the molecule. Among other things, this increased reactivity helps asparagusic acid break down rapidly and its derivatives are what researchers believe we smell after asparagus has been consumed.

However, it's important to note that people differ in three basic ways in terms of asparagus consumption and urine odor. First, there are differences in digestion while asparagus is inside our GI tract and differences in the absorption of asparagusic acid. Second, there are differences in the way we metabolize asparagusic acid if it gets absorbed up into our blood steam. And finally, there are differences in our ability to detect the presence of asparagusic acid derivatives. These factors can combine in such a way as to produce some unusual results. For example, one person might end up with significant amounts of asparagusic acid derivatives in his or her urine, but be unable to detect the odor, even when another person can!

There is one further important point that we would like to make about the urine odor of asparagus and asparagusic acid. This molecule has as its core component a sulfur-containing structure called 1,2-dithiolane. We have included asparagusic acid as a key nutrient in asparagus and we have placed this content about asparagus odor within our Health Benefits section because 1,2-dithiolane is a key structure for the formation of a key sulfur-containing organic acid and antioxidant called alpha-lipoic acid. In fact, it is the presence of 1,2-dithiolane that allows alpha-lipoic acid to participate as a cofactor in the enzyme activities of pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase. Both of these enzymes and their activities help provide a critical doorway into the pathways of aerobic metabolism, which requires special antioxidant protection. While researchers do not yet have a complete picture of asparagusic acid in terms of its antioxdant function, the presence of 1,2-dithiolane in its structure suggests that this function will be involved in a major way. “

According to the newsletter, asparagus now has its own plant family named after it—the Asparagaceae family.

Read the rest of the newsletter (above link) for more details about the nutritional value of asparagus.

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