Bile is green because it contains biliverdin, a green pigment formed from the oxidation of bilirubin.
Here's a breakdown:
- Bilirubin's Role: Bile initially contains bilirubin, a yellowish pigment.
- Oxidation to Biliverdin: According to provided information, "upon exposure to air, or even in the gallbladder, bilirubin is oxidized to biliverdin, which has a deep green color."
- Biliverdin in Bile: "Bile normally discharged into the intestine usually has a small proportion of biliverdin." This is what gives bile its characteristic greenish hue.
In essence, the presence of biliverdin, an oxidation product of bilirubin, is the primary reason for bile's green color. Biliverdin is derived from bilirubin through a process of oxidation, which occurs even within the gallbladder, resulting in the greenish color of bile.
