Comments on: Allura Red AC/FD&C Red Dye #40 (Why you don’t poo pink) http://www.moleculeoftheday.com/2006/06/07/allura-red-acfdc-red-dye-40-why-you-dont-poo-pink/ Molecules: You'd Better Learn to Live With Them Sat, 05 Jul 2008 02:08:41 +0000 http://wordpress.org/?v=2.0.2 by: Not My Second Opinion http://www.moleculeoftheday.com/2006/06/07/allura-red-acfdc-red-dye-40-why-you-dont-poo-pink/#comment-70 Fri, 09 Jun 2006 22:20:55 +0000 http://www.moleculeoftheday.com/2006/06/07/allura-red-acfdc-red-dye-40-why-you-dont-poo-pink/#comment-70 I've wondered why dyes don't come out the same color they go in as well... and I have a few more biological factoids to add. Bacteria in the gut also breaks down a byproduct of old hemoglobin, urobilinogen, and oxidizes it into stercobilin which gives stool its brown color. When urobilinogen is absorbed by the kidneys and converted to urobilin, it makes the yellow color of urine. Great blog! Keep them coming! :) I’ve wondered why dyes don’t come out the same color they go in as well… and I have a few more biological factoids to add. Bacteria in the gut also breaks down a byproduct of old hemoglobin, urobilinogen, and oxidizes it into stercobilin which gives stool its brown color. When urobilinogen is absorbed by the kidneys and converted to urobilin, it makes the yellow color of urine.

Great blog! Keep them coming! :)

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