Not Medical Advice: As explained by Mayo Clinic, stool color is generally influenced by what you eat as well as by the amount of bile, a yellow-green fluid that digests fats in your stool. As bile pigments travel through your gastrointestinal tract, they are chemically altered by enzymes, changing the pigments from green to brown.
Green-colored stool may mean food may be moving through the large intestine too quickly, such as due to diarrhea. As a result, bile doesn't have time to break down completely.
Possible dietary causes of green-colored stool are green leafy vegetables, green food coloring, such as in flavored drink mixes or ice pops, and iron supplements.
Learn more about the ABCs of poop at WebMD.
Tip! Check out the Best Foods to Eat for Healthy Bowel Movements, shared by SFGate.