183 Abstract There have been numerous reviews on the beneficial effects and health benefits of the soybean protease inhibitor known as the Bowman-Birk Inhibitor (BBI) [1–15]. The early in vitro studies were so promising that in vivo studies were performed at a very early stage of BBI development. The results of animal carcino- genicity studies were sufficiently promising that permission to perform BBI human trials was sought. It was planned that human trials using BBI would be performed with BBI Concentrate (BBIC), a soybean extract enriched in BBI. BBIC achieved Investigational New Drug (IND) Status with the FDA in 1992, and human trials began at that time. There have been six INDs involving BBI human trial work for the fol- lowing endpoints: cancer prevention (regression of a pre-malignant lesion known as oral leukoplakia), treatment of benign prostatic hyperplasia, prostate cancer detection and treatment (with measurements of prostate specific antigen levels and prostate vol- ume, etc.), treatment of ulcerative colitis, gingivitis, or esophagitis (and/or alleviation of adverse side effects of lung cancer treatment), as described elsewhere [15]. There are numerous publications on the results from these trial areas [16–21]. In this “expert opinion”, the current status of BBI experimentation and human trials will be discussed. 11.1 Studies on the Beneficial Effects of BBI/BBIC The Bowman-Birk inhibitor (BBI) is a soybean-derived protease inhibitor, which is known by the names of the scientists who identified and characterized it. BBI was initially discovered by Dr. Donald Bowman in 1946 [22] and was subsequently Chapter 11 The Health Benefits of the Bowman-Birk Inhibitor Ann R. Kennedy E. F. Fang and T. B. Ng (eds.), Antitumor Potential and Other Emerging Medicinal Properties of Natural Compounds, DOI: 10.1007/978-94-007-6214-5_11, © Springer Science+Business Media Dordrecht 2013 A. R. Kennedy (*) Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA e-mail: akennedy@mail.med.upenn.edu