Why is Bile green?
If we see the color of the bowel to be green, there might be two reasons for the green color. One of the reasons might be the ingestion of green leafy vegetables, or due to artificial green color or iron rich substances. The other reason is time taken for bowel transit in the gut. The gut transit will be rapid due to diarrhea and IBS. The bowel color depends on the type of food taken in as well as on the stage of the bile secreted in the liver.
Bile is green in color as the color is imparted by the bilirubin which is the product formed from breakdown of red blood cells. Heme gets broken down into bilirubin. Bilirubin is yellowish green in color. Heme is part of hemoglobin which is an important ingredient of red blood corpuscles. The green color of the bile is its original color and it changes to brown when the food is digested in proper digestive process. If the food is moving rapidly through intestines the time required for its change into brown color will not be sufficient and hence the food appears green.
The bilirubin is excreted through bile and urine. If the levels of bilirubin are more, it might lead to several diseases. The yellowish green color of the body parts while jaundice affects you is due to excess bilirubin levels. The yellow color of urine sometimes might be due to bilirubin. The formation of bilirubin results due to the action of biliverdin reductase on biliverdin. Biliverdin is a green bile pigment which is formed from catabolism of heme again. Bilirubin is the oxidized product of biliverdin.
Hence the yellowish green color of the bile is obtained from bilirubin and it is derived in turn from biliverdin. Bilirubin and biliverdin are two pigments of bile juice.