taken from Small Gland, Big Problem 4th Edition
by Professor Roger Kirby, Health Press 2011

Although we have still to identify the fundamental steps in the development of BPH, we know that testosterone is certainly involved in some way and it is likely that the female hormone oestrogen also has a role. Epidemiological data suggest that men in the Far East are protected, to some extent, against the risks of BPH by minute amounts of oestrogen-like substances in the food that they eat (for example, soya contains the phytoestrogen genistein). This raises the question as to whether dietary supplements taken regularly by men in Europe, the USA and elsewhere could protect against the risk of this disease. Long-term studies involving many men are needed to confirm this.