Weird Medicine

Asparagus Makes Pee Smell Weird With Asparagusic Acid, Which Isn't Found Anywhere Else

asparagus
Filled with crucial nutrients like Vitamin K, asparagus is quite healthy for you, but it can also cause an odorous urine. Photo courtesy of Shutterstock

Aside from the fact that the green, stalky vegetable is packed with nutrients like vitamin K — it may even prevent hangovers — it’s pretty well-known that asparagus can occasionally make your pee quite pungent. But where does the smell come from, exactly?

It seemed to appear that only some people could notice a strong odor from their urine after eating a lot of asparagus. Certain types of foods contain some odorous compounds that aren’t able to be broken down by the body, and therefore must be expelled through excrement. In the case of asparagus, the vegetable contains asparagusic acid, a chemical that’s not found anywhere else — at least not that we know of. When asparagusic acid is digested, it produces compounds like methanethiol and dimethyl sulfide, as well as dimethyl sulfone. Sulfur is known to contribute to skunk and rotten egg smells with their putrid odor.

Scientists hypothesized that some people were "excreters" while others were “non-excreters,” if they were unable to smell the odor in their urine. At the same time, others theorized that some were “smellers” and others were “non-smellers,” unable to detect the scent of methanethiol or dimethyl sulfide. Ultimately, after a slew of studies spanning several decades, scientists concluded that people could be both excreters and non-excreters, as well as smellers and non-smellers.

Here's the detailed reason your pee smells weird after eating asparagus. 

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