I'm assuming it must be regular black tea.  Although green tea is known for
its higher content of antioxidant activity, flavonoids, and polyphenols than
black tea.  Both are known to reduce the formation of carcinogenic substances
created during the cooking of meats, both contain a substance called quercetin
which has anti-inflammatory and anti-viral properties which can help reduce
LDL cholesterol, and have shown to inhibit the formation and growth of tumors,
mainly as a result of its polyphenolic compounds which may inhibit cancer by
blocking the formation of carcinogenic compounds created in the digestive
tract, thus suppressing the action of potential carcinogens, and detoxifying
carcinogens in the body.  Also, a further benefit is that black and green teas
may help control cavities and tooth decay.   Sources are from "Better
Nutrition" journal, Jan. 1998.

On a side note, I myself concieved when I switched from drinking coffee to
Earl Grey tea.