Theanine added to Melatonin?

Question

Does Theanine cause changes in the color of bowel movements?

Answer 1

I looked at several websites and saw no mention of this side effect. However, I would say if your l-theanine is GREEN it might cause a harmless darkening of the stool.

Never had anyone mention melatonin doing this either.

Blood (or beets or Pepto-bismol) will turn the stool dark. So if your stool is black you might want to have a health care provider look into it.