I recently started drinking tea all the time, and it helps me feel better when I’m sick. I also drink coffee, but lately have been favoring tea since I know that coffee is bad for you. A friend at work suggested that green tea is good for your immune system, but regular tead isn’t necissarily good for you, just not as bad as coffee. Anyone know the straight dope on this one?
Facts I know about tea:
Higher in caffeine than coffee
Green tea is supposed to be very good for you - they drink it in Japan all the time.
Coffe makes you hyper, but tea has a more relaxing effect.
Ways tea is good for you: Most tea is lower in caffeine than coffee (approximately half as much a coffee, depending on the type, and how it’s brewed), and green tea contains less than black. Tea contains theobromine, which slows your body’s absorbtion of caffeine, which cuts back on the jitters. It also contains antioxidants, which are supposedly good for you in many vague ways.
Ways tea is bad for you: It contains caffiene. It’s a diuretic, which means that it causes your body to get rid of water. Common myth to the contrary, tea contains more water than its diuretic effect will cause you to lose, so you won’t dehydrate because of it, but it’s not as hydrating as other drinks.
I just got a fabulous Ooolong from my Tea of the Month club, so I’ll be brewing a pot while you mull over the health risks. 
“Tea is good for what ails you,” says Consumer Reports, March 2003. (Not on its website www.consumerreports.org.) The benefits come from the plant Camellia sinensis, so herb teas don’t have the same benefits. This article states that many studies suggest that tea may help fight heart disease and certain cancers a well as increase bone density.
Tea is rich, the article states, in a class of disease-fighting antioxidants called polyphenols. Antioxidants neutralize molecules called free radicals, which can damage cells and tissues over time and, in theory, contribute to chronic diseases such as cancer. The article then summarizes the results of some studies.
Tea may help protect the heart, the article continues, by relaxing blood vessels; by inhibiting blood clots, which can trigger a heart attack or stroke; and by helping to improve cholesterol levels. The article now summarizes the results of other studies indicating this health benefit.
Tea leaves coontains fluoride and phytoestrogens, the article continues, which may increase bone density and, in theory, guard against osteoporosis. The article now summarizes the results of studies showing this benefit.
Tea, especially green tea, has far less caffeine than coffee and somewhat less than black tea.
Black, green, and oolong refer to the method used to process the leaves. Green tea is the least processed. The leaves are steamed, roasted, or pan-fired almost immediately, leaving little chance for them to oxidize. Black tea leaves oxidize for at least several hours. Oolong tea is partially oxidized.
Bottled teas have slightly less antioxidant potency.