Studies of humans and animals show that the antioxidants in black and green teas are highly beneficial to our health, says  John Weisburger, PhD, senior researcher at the Institute for Cancer Prevention in Valhalla, N.Y.Green tea & black tea, derive from the same tea plant, Camellia sinensis. The leaves are simply processed differently. Green Tea leaves are not fermented,they are withered and steamed. Black tea and oolong tea leaves undergo a crushing and fermenting process.