It could also be a parasite in your stomach.....well intestine tract....I had this green stool problem for 6wks! I went to doctor he said it was due in part to a respatory problem...gave me storoids and it went away...along with the fever and weak feeling I had. I didn't have the parisite but it was/is possible....if u have it it can cause green stool...its called Giardia
Blue dyed food, ice cream, can result in neon green stools. My kids taught me that one, lol!
If you have the occasional green stool—don't panic! Most likely it is normal, and there is a perfectly reasonable explanation. Think about the foods you ate, any vitamins or supplements you took—even if they're not green in color.
There can be many reasons why stool appears to be green. The first and most obvious reason is eating green foods. Green, leafy vegetables contain chlorophyll which could be coloring the stool green. Foods with dark purple coloring like Kool-Aid, popsicles, and gelatin (Jell-O) can also result in rainbow-colored stools. Iron supplements or even foods that are rich in iron can also give stool a green tinge.
Stool can also appear green for physical reasons, and not just from what you've been eating.
We think of a healthy stool as being brown. Bile that is secreted in the first part of the small intestine is actually green. As stool is digested and passed through the large intestine it is turned into a darker brown color.
If stool is still green by the time it is excreted, it could mean that it went through the large intestine too fast to be changed in color. This is often called "rapid transit" or "decreased colonic transit time" and diarrhea that is green in color could be the result.