I think there is some good advice here, but don't forget that thanks to our industrialized planet and subsequent acid rain, the tea plant often absorbs flouride more easily than other types of commonly consumed plants. Because of this, I think the 8 cups a day (if one tea bag per cup) is way over-kill. It was mentioned elsewhere on this site (and in many other credible contexts) that 1 cup of green tea can have the same flouride content as 8 liters of municipal water! FYI, per the AMA, 28% of bladder/intestinal cancer are a direct result of consuming flouridated water! ~8 cups a tea over a long period of time may contribute to this risk.
Remember that flouride is only helpful topically, not systemically. Therefore, it's best to get your flouride from toothpaste/mouthrinse, spitting it out after use, than from ingestion.
I'd have to say the minimum consumption is more like 1 cup, not 8! Since any measureable amount of anti-oxidants are better than none at all. So, even 1 cup of of green, black, regular, herbal, or white (has the highest anti-oxidants) is better than none. Also, let's not forget that I believe it was LL who wrote that you can actually consume TOO MANY anti-oxidants! I believe he stated that anti-oxidant intake should be proportional to your oxidation rate (physical activity and calorie needs).
I think 1-2 cups a day as long as it is a quality/potent tea is good. For additional antiox's, try getting them from other sources to avoid excess flouride. Such sources include fresh fruits and veggies; specifically alpha lipoic acid, berries, garlic, and there are great polyphenols (what's in tea) in thyme and oregano.