Jul 03 2013

Biochemistry Question For Readers

Why does the red pigment in beets stay red in your poop, but the red pigment in wine turns black?


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  1. 1

    Beets contain this shit. It’s bizarre and unique to the family and the human digestive system sez wtf?
    The red stuff in wine is anthocyanins instead; these are very common plant pigments and I guess they get partially digested. Or it’s a pH thing.
    that’s all I got.

  2. 2

    Oh I can’t resist. What about the pigment in… pork?

  3. 3
    recent Ph.D.

    I suppose it would be dumb to even ask if that question is the result of self observation.

  4. 4

    I read this, then went on a three hour car trip, and have therefore thought about this WAY too much. I think 3 things are going on:

    1) simple concentration. Wine contains about 80 mg/kg anthocyanins, beets contain about 500 mg/kg betanin. Might be hitting the limit of absorption with beets

    2) extraction. All the anthocyanins in wine are already dissolved in an aqueous solution, and can be more efficiently absorbed. The beets enter your system in various states of pulverization, depending how well you chew your food. The test would be beet juice, naturally.

    3) intensity. The extinction coefficient for betanin is about twice that for anthocyanins, so you need half as much to see the same red color

  5. 5

    I suppose your next question will be about the persistence of capsicum in fecal matter and whether the ingestion of large amounts of overtly expensive cheeses mitigate the effects thereof?

  6. 6

    No, the next logical question is why your pee smells of asparagus after you eat asparagus, but not of stinky cheese after you eat stinky cheese.

  1. 7
    Biochemistry Question For Readers » Comradde PhysioProffe | biochemistry | biochemistry blog | protein | nature biochemistry

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