Kevin's Watch

When you eat asparagus, why does it make your pee smell?

In 1891 a scientist named "Nencki" had so very little to do that he convinced four guys to eat seven kilograms of asparagus (that's about three and a half pounds each). He collected the pertinent pee, worked some medieval magic on it, and concluded that the smell was due to a metabolite called methanethiol.

So there you go. Nencki claimed that as your body metabolizes asparagus, it produces this smelly chemical, which your discriminating kidneys see fit to dump into the bladder.

Courtesy of Discovery Online

It's the result of a simple chemical reaction. Asparagus contains a sulfur compound called mercaptan. (It's also found in rotten eggs, onions, garlic, and in the secretions of skunks.) When your digestive tract breaks down this substance, by-products are released that cause the funny scent. The process is so quick that your urine can develop the distinctive smell within 15 to 30 minutes of eating asparagus.

But not everyone has this experience. Your genetic makeup may determine whether your urine has the odor -- or whether you can actually smell it. Only some people appear to have the gene for the enzyme that breaks down mercaptan into its more pungent parts. A study published in the May 1989 British Journal of Clinical Pharmacology found that 46% of 115 people tested produced the odor in one group of British citizens, while 100% of 103 people produced it in a group of French citizens. The ability to smell the by-products may also be genetic. Another study published in the same journal found that 10% of a group of 300 Israeli Jews could not detect the odor. In other words, a person's urine could smell, but he or she might not know it.

--A

Just for clarification methanethiol is a member of the class of chemicals mercaptan.

Thank you both!

Av's quote said:

A study published in the May 1989 British Journal of Clinical Pharmacology found that 46% of 115 people tested produced the odor in one group of British citizens, while 100% of 103 people produced it in a group of French citizens

Shall we have an international KW study then, to see what percentages of other nationalities can smell asparagus pee?

Me (Irish) can.
GF (Korean) can.

I (1/4 of each of the following: Polish/Austrian/Russian/Scot and yet 100% American Jew) both produce smelly urine and can smell it.

I am a typical American mutt (part Scottish, Irish, English, Swedish, Cherokee, & German) ~ and my guess is that I cannot smell asparagus pee. I do eat asparagus, and never even knew that it makes pee smell weird.

:::warning, TMI post ahead:::

I love asparagus, and will eat great quantities of it when in season. But, I notice the change in my urine right away, and it's so bad even Paul and Beorn can guess I've eaten dasparagus if they use the restroom within 10 minutes of me having done so.

So then I must either not have the gene that has my body break down the asparagus into the smelly chemicals or I do not have the gene that allows me to smell the weird smell, or both.

Given that I love to eat fresh asparugus, either one or both of those conditions are probably a good thing.

Duchess wrote:

So then I must either not have the gene that has my body break down the asparagus into the smelly chemicals or I do not have the gene that allows me to smell the weird smell, or both

But then again, do you normally smell your pee? Doesn't necessarily stink out the restroom!

Given that I love to eat fresh asparugus, either one or both of those conditions are probably a good thing.

And now, , you'll be smelling your pee every time after eating asparagus!

(Every time I see you post, I can't help but think of Roquefort's "Duchessss, Kitttttennnnsssss?"!)

Stonemaybe wrote:When you eat asparagus, why does it make your pee smell?

Because it smells like it tastes.

this thread has put all sorts of unpleasant images in my head.

High Lord Tolkien wrote:

Stonemaybe wrote:When you eat asparagus, why does it make your pee smell?

Because it smells like it tastes.

Never tasted that.... Asparagus yes... but not.............

Im wondering if eating yoghurt or taking an acidopholis bifidus (sp) supplement might dull the effect

Has anyone documented/experienced the effect of Vegemite on renal byproducts?

Infelice wrote:

Im wondering if eating yoghurt or taking an acidopholis bifidus (sp) supplement might dull the effect

wouldn't think so, as they would affect the digestion, not the metabolism.

Has anyone documented/experienced the effect of Vegemite on renal byproducts

Any Atlantic-crossers know if Vegemite is what we call Marmite? If so, I believe that the scientists conducting the experiments produced inconclusive results because they were so busy !!!

It's similar, but not the same.

--A

I eat marmite every day and haven't noticed any renal by-products. Does this mean that I cannot smell funny, odorific urine? I can however smell asparagus tainted pee. What does it all mean???????????

I always thought vegemite was the same thing. Oh well. I am glad I never bought any!

Not the same. I love marmite. Not any of the substitutes though.

--A

marmite but parwill.

I'm too lazy to search, but that must be one of your favourite jokes. I'd swear you've made it every time I've posted the word marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite. Marmite.

Sorry. Had to get that out of the system.

--A

OK, Av's loosing it. Maybe this will help.

Roasted Asparagus with Balsamic Browned Butter

Heat oven to 400°F. Spray a cookie sheet with Pam. Put your dry veggies on the pan and season with salt and pepper. I give them a quick spray with Pam on top too. Aspragus then goes in the oven for 10-12 minutes. Times vary depending on the veggies.

Balsamic Browned Butter

2 TBS Butter (must be full fat regular butter)
2 tsp soy sauce (I use light)
1 tsp balsamic vinegar

Put butter in small saucepan and heat on medium until browned. This happens quickly so be close. Remove from heat then add soy and vinegar and stir. Drizzle over roasted veggies and serve.

Roasted Asparagus with Pecans and Sun-Dried Tomatoes

1 pound asparagus (the thin kind in a bunch)
1 tablespoon chopped pecans
3 tablespoons oil-packed julienned sun-dried tomatoes, drained
1 teaspoon extra-virgin olive oil
1/4 teaspoon salt

Preheat the oven to 375ºF. Cut 1/2 inch off the ends of the asparagus. Rinse the spears and pat dry.

In a small baking dish, drizzle the asparagus, pecans, and tomatoes with the oil (I use the oil from the tomatoes) and sprinkle with the salt. Stir to mix.

Bake for 8 to 10 minutes (I still prefer 10 to 12 minutes), or until the asparagus is crisp-tender.

Per serving: 65 calories, 3 g fat (0 g sat fat), 3 g protein, 6 g carbohydrate, 3 g fiber, 0 mg cholesterol, 159 mg sodium