What Is Oolong Tea Extract? Oolong tea extract is made from the leaves of the Camellia sinensis plant, the same plant used to make black and green teas. The difference is in processing: black tea is fully fermented, green tea is not fermented at all, and oolong tea is partially fermented. Oolong Tea Extract Benefits Oolong tea extract is rich in polyphenols and may help aid digestion.* It is heart-healthy and may support the brain, promote healthy mood, and help support the skin.*