The next ingredient in Essiac is turkey rhubarb, an herb that has demonstrated anti-tumor activity in animal tests. In smaller doses, turkey rhubarb is used to treat diarrhea or to stimulate the appetite.
Larger doses yield a laxative effect.
This common garden plant bears no resemblance to the Rheum palmatum mentioned in the Flor-Essence and other products. This is probably the one of the most important reasons for the difference in the performance of the different formulas apart from the actual quantities. Rheum officinale prefers a slightly warmer climate and at a lower altitude than the very cold climate native to R. palmatum. Most herbal encyclopedias do not separate the many varieties of Rhubarb and it is not until you explore Chinese herbal references that you uncover the different varieties and chemical properties. The price and availability is probably the main reason the fakes use the alternatives.