In Triumph of the straight dope, Cecil discusses the relative caffeine in tea and coffee. But coffee has caffeine and tea has theophylline ( and cocoa has theobromine). All of these chemicals are Xanthines. Is there any research on the different effect of these xanthines on people. Or are they so close that it’s meaningless to differentiate between caffeine and theophylline, and easier to wrongly call the stuff in tea caffeine?
I cannot find any references to coffee, tea or caffeine in the index for Triumph of the Straight Dope. What page is that on?
AFAIK, The caffeine in tea is identical to the caffeine in coffee.
Possibly 211-212? (Found by looking under T (for theobromine) in Triumph’s index. That the discussion you were asking about Joan?
Your Official Cat Goddess since 10/20/99.
They are pretty much the same. All can give odd heart rhythms if used in excess.
Must’ve been hallucinating. Actually I must’ve read the old "tea has more caffeine than coffee, no it doesn’t " debate, with comparisons of pop caffeine levels to follow somewhere else when I was also reading this book. My deepest apologies. I’ll check page numbers and citations before every post from now on. Whoops.
No problimo, Joan. Just the fact that someone owns and reads an Uncle Cecil is good enough for us. Hallucinations are part of the game. 
Caffeine: 1,3,7-trimethylxanthine.
Theobromine: 3,7-dimethylxanthine.
Theophylline: 1,3-dimethylxanthine.
All of them have similar pharmacological properties because they’re all quite similar molecules. However, they’re not identical, and tea contains all three.
Caffeine does have the alternate names coffeine, thein, and guaranine (it’s found in guarana also); I suspect that these names were given before it was known that they referred to the same molecule derived from different sources.
Xanthine itself also occurs in both coffee and tea (and in “animal organs, yeast, and potatoes”); however, no pharmaceutical category is listed for it, probably because it’s not very soluble (it’s somewhere on the order of 200 times less soluble in water than caffeine is).