Our expert says:
I must confess I've never heard of green stools as a result of running. Red yes, that's fairly common, but I've not heard of green. I can't see how gels would cause that.
I am reliably informed by some research on the internet that green stools can result from the rapid movement of feces through the intestines. Bile is green, and so the rapid movement of stools through the intestine prevents bile from having its effect and green stools are the result. That seems the only explanation I can find for it, and no mention at all made of anything to be concerned about. Obviously, that's not a medical opinion and you might cnosider finding out, but I suspect it's nothing to be overly concerned about.
The information provided does not constitute a diagnosis of your condition. You should consult a medical practitioner or other appropriate health care professional for a physical exmanication, diagnosis and formal
advice. Health24 and the expert accept no responsibility or liability for any damage or personal harm you may suffer resulting from making use of this content.