Speculations about Burger King's Halloween Special black bunned Whopper circulated the web last September.  This week, Burger King confirms the rumors and released its spooky black bunned whopper.  It was reportedly made of A1 steak sauce and just a little bit of food colouring which they said meets the FDA safety guidelines.  However, this is not the only treat Burger King has in store for its fans.  Those who have consumed the Halloween Whopper is reported to poop not just green, but bright comical green poop.

There are several assumptions as why this phenomenon happened.  As reported in the National Post, your bright green poop is most likeley the evidence of a green or blue food colouring.

It is expected that certain colours of food can change the colour and consistency of your stool.  Take vegetables for example.  It is highly possible that an excess consumption of green vegetables can give your poop a green hue.  However, this is not the same shade of green in Burger King's Black Whopper's case.  So the most bet goes to green dye.

The original Japanese black bunned burger uses bamboo charcoal and squid ink for both flavour and colour.  However, the U.S. edition did not use burnt bamboo, instead the only ingredient of the bun that was publicly mentioned is the A1 steak sauce.  Common sense will tell that the super black pigmentation does not come from the steak sauce alone.  It would definitely involve some experimenting to reach the desired effect and dark green seems to be used as any dye colour.

It may also be purple or blue food dye if you're not really sold out with the green.  This has also been known to cause bright green stools.  As evidenced by drinking a bunch of grape Kool-Aid.  Try for yourself.

There also endless possibilities why your poop can turn bright green.  This maybe because of bile or the effect of iron supplements.  Neither which is applicable in making a bread.  So the green or blue dye theory probably hits closest to home.

Meanwhile National Post reached out to Burger King to confirm the ingredients of the black buns.  As of this time, Burger King has not responded.