The Washington Post won’t pursue definitive answers for what happened at Benghazi, what Sid Blumenthal was up to in Libya, or why Chip Kelly dumped Tim Tebow, but by gum, they are determined to get to the bottom (as it were) of why Burger King’s black-bunned A1 Halloween Whopper is turning your poo green.

And I’m not talking about pea-green or Army green or a lovely shade of celadon, we’re talking plastic-leprechaun-hat green.

Be warned, what you will find at this link isn’t pretty. But in the interests of science and truth, see for yourself.

This isn’t the first time Burger King has gone goth. Last year in Japan, it introduced the “All-Black Everything Cheeseburger,” or “Kuro Burger.” Bamboo charcoal blackened the bun and cheese (yes, the cheese), and the black onion-and-garlic sauce contained squid ink. The burger was normal meat color, but flavored with black pepper. We have no word on whether any horrifying toilet moments similarly threatened Japan’s sanity, but since charcoal is known to neutralize odors and act as an absorbent (you can even take it in pill form), it’s possible that it may have even … helped some folks.

The American version features just a black bun, with all the regular Whopper meat and condiments, plus the A1. To quote BK:

Introducing the A.1.® Halloween WHOPPER® Sandwich with A.1.® flavor baked into the black bun. The sandwich is a ¼ lb. of savory flame-grilled beef topped with melted American cheese, ripe tomatoes, crisp iceberg lettuce, creamy mayonnaise, A.1.® Thick and Hearty Sauce, crunchy pickles, and sliced white onions on a soft sesame seed bun with A.1.®flavor baked into the bun.

Some intrepid reporters have downed the limited-edition sandwich to see the results for themselves – and one Today.com correspondent admitted:

The verdict: it’s kinda, sorta … well … okay, really good. The black bun has the squishiness of a Martin potato roll and a tiny hint of black pepper that’s a good complement to the smoky charcoal-broiled burger, crunchy iceberg lettuce and creamy mayo. I can’t believe I’m saying this, but the addition of the A.1. sauce really brings out the umami flavors of the sandwich. Who am I?

This writer didn’t reveal whether or not there were any intestinal ramifications. But, the Washington Post, ever on the job when answers need to be found about things that really matter, took it a step further and decided to dig down to the root cause of the issue. They weren’t inclined to blame it on the steak sauce, which has been dumped on perfectly good meat since 1831, and contains such delicacies as tomatoes, raisin paste, corn syrup and xanthan gum. Lacking the exact list of bun ingredients, and still awaiting a comment from Burger King, WaPo concludes it was food dye:

Dark green seems as likely a dye color as any. Furthermore, purple or blue food coloring — another, perhaps even more likely dye choice for a deep black bun — has also been known to cause bright green stools. Ask not why the purple dye turns poops green, just go drink a bunch of grape Kool-Aid and see for yourself.

Tech blog Gizmodo concurs, but offers an excruciating amount of detail:

But while the poop is indisputably green, the dye causing it might not be. The dyes that make the bun black are a combination of Yellow #6, Red #40, Caramel Color, and Blue #1. Blue #1 is also known as Brilliant Blue FCF. Brilliant Blue doesn’t absorb well in the intestines, so it often comes out in the poop — it just doesn’t come out blue. The internet is full of concerned parents talking about giving their kids a purple drink or smoothie (made with red and blue food coloring) only to change green diapers or find green stains on underwear. Brilliant blue is often combined with tartrazine, a yellow food dye, to make green dye. A site called The Poop Report claims that blue food dye (Blue #5 this time) combines with bile to make poop green, although bile by itself can turn poop green. In the end, the green product of the black burger is probably the result of blue food coloring. The good news is that it’s coming out of you because it’s not getting absorbed into your body.

Of course, if you haven’t eaten an A1 Halloween Whopper and your poop is green, science has answers for that as well:

The spooky Whopper also inspired a bit of creativity, and isn’t that what Halloween is all about?



So, does the A1 Halloween Whopper pose any real health risks?

Well, if your medical professional is cool with consuming 710 calories (390 from fat), 43 grams of fat (15 saturated; 1.5 trans fats), 105 mg of cholesterol, and 1530 mg of sodium in one sitting, go for it.