A staple drink of many Asian nations for thousands of years, green tea has a rich store of many beneficial nutrients, including catechins, a group of potent antioxidants. The use of green tea extract has been suggested to ward off a host of conditions ranging from heart disease to obesity. According to the University of Pittsburgh Medical Center, research on some fronts seems promising but has produced mixed results. Whether or not using green tea in supplement form will produce any therapeutic benefit has not been conclusively established. Like drugs, natural supplements can sometimes produce negative effects, and some potential medication interactions have been noted with the use of this supplement. Check with your doctor before using green tea extract or any herbal treatment if you take prescription drugs.