In 2005 the French AFFSA has published an evaluation of more than 440 pages on benefits and safety of isoflavones. In this well-documented paper it was concluded that isoflavones can be considered safe up to a dose of at least 60 mg/day, corresponding to approximately 1 mg/kg body weight (Anon 2005). This conclusion obviously differs from the assessment of the German BfR in 2007 (Anon 2007).
The AFFSA assessment does not say that higher doses are in fact unsafe, but merely points to the lack of data for such dose schemes. In contrast the collection of references used by the BfR points to a rather sloppy literature research. It must be taken into consideration that at the time when the BfR made its assessment it could and should have taken note of more recent and better safety data than the AFFSA had available in 2005. As most of the questions raised by the AFFSA in 2005 have meanwhile been answered, the conclusions should today even be more in favour of isoflavones.
The negative benefit to risk ratio alleged by the German BfR is clearly not in line with the available data, especially as between the lines the BfR itself speaks of a “low probability”, and refers to “isolated isoflavones” as in contrast to soy food preparations - but still strongly disrecommends the use of soy isoflavone products in its press releases.
References
Anon. (2005). Sécurité et bénéfices des phyto-estrogènes apportés par l'alimentation - Recommendations. Paris: AFSSA.
Anon. (2007). Isolierte Isoflavone in Nahrungsergänzungsmitteln und bilanzierten Diäten. Gesundheitliche Bewertung des BfR vom 30. 11. 2007
Safety 