For more details on this topic, see deuterium. A deuterium atom contains one proton, one neutron, and one electron. 2H (atomic mass 2.013553212724(78) u), the other stable hydrogen isotope, is known as deuterium and contains one proton and one neutron in its nucleus.
The caffeine in green tea, especially when taken in large amounts, can worsen diarrhea. Irritable bowel syndrome (IBS) : Green tea contains caffeine. The caffeine in green tea, especially when taken in large amounts, can worsen diarrhea and might worsen symptoms of IBS.
For most people, these side effects are merely bothersome. However, green tea can sometimes cause serious side effects as well, especially when taken at higher dosages. Generally, serious green tea side effects are due to the caffeine content of green tea. (This article covers many, but not all, of the possible side effects of green tea. Your healthcare provider can discuss a more complete list of side effects with you.).