Isoflavones: toxicological aspects and efficacy

In Asian countries, coronary heart disease as well as breast and prostate cancer are less frequent than in Western countries. Because the traditional Asian diet consists of more soy-based food products than the Western diet, soy constituents, namely isoflavones are believed to cause beneficial health effects. However, although a plethora of cell-free studies, studies in vitro and in vivo, and studies in humans have investigated a multitude of putatively beneficial effects, no health claim directly related to isoflavones has been approved up to now. Likewise, despite ongoing safety evaluation of isoflavones by scientific expert panels, no conclusive statement on the safety of dietary isoflavone supplements has been reached. This chapter summarizes the current knowledge on toxicity and efficacy of isoflavones, focusing on biokinetic properties and biotransformation of isoflavones necessary to understand the heterogeneity of study results and other difficulties in evaluating the safety and efficacy of isoflavones.