That&#x27;s interesting.  Now that I think of it, the nausea feels exactly like what you get from ingesting the tannins in overbrewed black tea.  I just assumed my nausea from drinking green tea and from L-Theanine (which I know that green tea contains in a non-negligible quantity).  Maybe levels of tannins in green tea are higher than in black tea?  In that case the nausea from L-Theanine may be unrelated.  Maybe it&#x27;s a combination of both.