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Answers from TODAY: Why does asparagus make your urine smell?

Mark Bittman showed off this morning four ways to cook asparagus -- but what Matt Lauer called the most important question stumped him: Why does the green vegetable make urine smell so strong? Watch Matt ask Mark in the clip below.

Mark Leyner and Dr. Billy Goldberg explained the answer in their book, "Why Do Men Have Nipples?”

"Asparagus contains a sulfur compound called mercaptan. It is also found in onions, garlic, rotten eggs, and in the secretions of skunks," they wrote. "The signature smell occurs when this substance is broken down in your digestive system. Not all people have the gene for the enzyme that breaks down mercaptan, so some of you can eat all the asparagus you want without stinking up the place. One study published in the British Journal of Clinical Pharmacology found that only 46 percent of British people tested produced the odor while 100 percent of French people tested did."

The Body Odd also covered this topic a few months back and reported that not everybody gets stinky pee after eating asparagus. 

From the blog: "About 8 percent of 38 test subjects who ate roasted asparagus (yum!) did not have smelly pee. About 6 percent could not smell the odor. One lucky person could not do either."

To read a short excerpt from Leyner and Goldberg's book, click here