tea contains caffeine (somebody told me it has more than coffee, I don’t know if that’s true…)
Church says that tea
[ol][li]Is prohibited as discussed previously in this thread[/li][li]Has caffeine, which is a drug.[/ol][/li]A scientific opinion on 1 would be "Yes, the LDS Church says that tea is prohibited. A scientific opinion on 2 would be “Yes, caffeine is a drug.”
However, the Word of Wisdom does not say why coffee and tea are prohibited. Caffeine is not listed, nor are tannins, nor any of the other chemicals found in those drinks. Anything besides coffee and tea is up to the individual. Soda is not strictly prohibited, nor is chocolate, though obviously a conscientous follower of the WoW would be careful not to become dependent on those.
I understand the First Presidency and the 12 Apostles love chocolate.