Interestingly, there is another such discussion in another internet tea group. I think Amadeus is right that adding things to tea muddles the original fine taste. However, if your tea is not so good to start with, there is nothing wrong in putting things to it to make it taste better.
On the effects of milk and sugar on tea, the real concern is not about the lowering of anti-oxidative effect, but rather the adverse health effect of the habit of sugar and milk throughout the day.
