green stool

Why is my stool green?  I will be 50 years old shortly.  I am on no medications and have no health problems that I am aware of.  Periodically, (like once last year & then a couple of times this month) my stool is grass green, usual normal consistency, & stays that way for a few days.  What would cause this?

[gnorb]

A few things: too much bile in the stool (could indicate a future upcoming gallbladder issue a few years down the line), decreased colonic transit time, so that the stool doesn't have time to change colors. Some food colorings and certain vegetables will cause stools to be green. Really, green is about the most un-worrysome color for stools to turn. If you're worried, talk to a doc, but you're probably just fine.

[Denise44]

I've had that same issue from time to time and found that if I eat black licorice or a blue slushie, it will give me green stools.