Why Is Poop Brown And Pee Yellow?

"Hi, this is Emily from MinuteEarth.
Although the things we eat and drink are all sorts of colors, they all come out the other
end looking either brown and yellow.
And actually, our digestive systems destroy pretty much all the colors in our food, turning
what’s left into a grayish mass – the pigments that show up in our poop and pee
come, not from our food, but instead, from our blood.
That’s largely because our bodies produce an insane number of red blood cells, but these
cells have no way of maintaining or repairing themselves, so they only last for a few months
before becoming so stiff and inflexible that they’re forced to retire.
If all the retiring red blood cells went straight to the toilet, and took all their oxygen-carrying
iron with them, our poop and pee would be red, but our bodies would also quickly run
out of iron for making new red blood cells, and we'd die.
Instead, white blood cells engulf their red comrades and crack them open to reclaim the
precious iron, leaving the disposable iron wrappers to degrade into a molecule called
bilirubin.
The liver tries to clean bilirubin from the bloodstream by sweeping it into the intestines...but
unfortunately, the intestines mistake it for food, and push it right back into the bloodstream.
In other words, left to their own devices, our bodies send bilirubin on an infinite loop
and never actually get rid of it.
Fortunately, certain gut bacteria break the cycle by intercepting bilirubin and chewing
it into a slightly different molecule called urobilinogen, which prepares it to finally
leave the body by two possible routes:
In route Number 1, urobilinogen first gets treated just like bilirubin and put back into
the bloodstream, but from there, it gets slurped up by the kidneys, which recognize it as trash
and process it accordingly – into a molecule that happens to be yellow – before passing
it along to the bladder, which passes it to the toilet...or, to wherever.
In route Number 2, microbes back in the intestines happen upon the urobilinogen and chew it into
a dark brown molecule that lurches all the way to the end of the colon, mixing with the
grayish remains of our food to turn the final product its familiar shade.
In short....
Roses are red, red blood cells are too Bacteria turn them into the brown in our poo
Except when our kidneys end up making them yellow
In which case, always remember to let it mellow" This episode of MinuteEarth is supported in
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Why Is Poop Brown And Pee Yellow?

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