The Science Behind Asparagus Pee + Asparagus & Sweet Potato Soup with Bacon and Poached Egg

You know those revelations that just totally rock your world and skew your entire perspective of the universe? Like when we learned the world wasn’t flat, the tooth fairy wasn’t real and that planting a Skittle in the garden doesn’t grow a package of Skittles anymore if you don’t live with your Dad?  Well for me, the fact that everyone has asparagus pee, it’s just that only some of us can smell it totally rocked my world.

Asparagus pee has been a long-recognize phenomenon (Benjamin Franklin once wrote in a 1781 letter to the Royal Academy of Brussels that “a few Stems of Asparagus eaten, shall give our Urine a disagreable Odour”). Asparagusic acid (which shockingly is only found in asparagus) has no odor until it is broken down into volatile sulfur-containing compounds in the process of digestion, which is why asparagus doesn’t smell but your pee may smell very quickly after eating it.

I knew there was a genetic component behind it (the one thing I took away from 10th grade biology), I just had always thought that you either had asparagus pee or you didn’t.  While scientists are still somewhat divided on the issue, it appears more likely to be a matter of perception – if your pee doesn’t smell when you eat asparagus, it’s likely because you can’t smell the sulfurous compounds, although there is still a small chance that it’s because your body digests asparagus differently, reducing the concentration of the chemicals.  Clearly, more research needs to be done.

Regardless, these are all things to think about while enjoying this ridiculously delicious soup, which I made with asparagus from my early CSA bounties.  Maybe you can even do some experiments at your next dinner party, asking your guests to help you determine whether it’s a matter of production of perception.  If you do, please report back!

Asparagus & Sweet Potato Soup with Bacon and Poached Egg

A Notes from a Messy Kitchen Original

Ingredients:
• 1 tablespoon olive oil
• 1 medium yellow onion, diced
• 3 cloves garlic, minced
• 1 tsp smoked paprika
• ½ tsp cayenne or chili powder (optional)
• 1 tsp dried thyme
• 12oz asparagus, chopped (reserve the top half of several spears for serving)
• 1 large sweet potato, chopped (~400g)
• 2 cups chicken or veggie broth
• 1 cup milk*
• salt and pepper to taste

*Regular or non-dairy alternative. I used cashew milk.

Toppings:
• Poached eggs (1 egg per serving)
• Crisp bacon or prosciutto, chopped* (1 slice per serving)
• Reserved asparagus spears

*Can use turkey or soy bacon if desired

How-to:

1. Heat olive oil in a large saucepan or dutch oven over medium heat. Add the onion and garlic, paprika and chili powder and cook for a couple of minutes. Add the asparagus and sweet potatoes and sauté until the onion is soft and translucent. Add broth and milk and cook for 15-20 minutes, or until the potato is soft.
2. Use an immersion blender, regular blender or food processor to blend until smooth. Return to the stove top and stir in thyme, salt, pepper and additional paprika and chili powder to taste.
3. Top with chopped bacon, a poached egg, an asparagus spear and a sprinkle of fresh ground pepper.

Serves 4 with a side salad

Johanna