Few subjects are so intensely debated as the use of plant preparations and the putative toxicity or safety of their active compounds. Ardent advocates and opponents can be found for both points of view and debates are still ongoing. The arguments used however, are not always fully scientifically based or only those data supporting a specific point of view are considered. The resulting problem is that very frequently an incomplete picture is given concerning the actual knowledge of the topic. This not only is very confusing but also does not lead to a better understanding of the subject. Therefore it is essential to identify the precise and real issues that need further clarification by scientific research. This book is an attempt to offer a positive contribution to the problem. Here we have tried to give an overview of the actual scientific knowledge related to the main plant species used to support gastrointestinal health through their stool promoting and/or laxative effects i.e. Senna, Rheum, Frangula and Aloe spp. Botanical, chemical and clinical aspects are considered in addition to pharmacokinetics, pharmacodynamics and safety aspects. It is only by combining these different approaches that a final and more complete picture can be obtained.