Not all soy products are created equal: caution needed in interpretation of research results

Interest in the health benefits of soy foods has been intense among the research community, health professionals, and the public. At the same time, potential concerns associated with soy consumption, especially as related to soy isoflavones, have tempered the enthusiasm for making public health recommendations. On both accounts, the primary soybean isoflavone, genistein, has received the most attention. Because consumers are becoming increasingly confused by the often conflicting dietary messages, a balanced and accurate view of the risks and benefits of soy foods and soy food components is essential. Even among health professionals, confusion exists about proper nomenclature and about the precise composition of the agents under investigation. Levels of isoflavones are frequently assumed to be constant within categories of soy foods, and intakes are estimated rather than being directly analyzed. Furthermore, all too often research dealing singularly with genistein is interpreted by both health professionals and the media as equating directly with soy. Researchers often fail to fully understand the implications of their research outcomes and the context in which those outcomes should be placed. With the hundreds of publications yearly on soy and isoflavones, it is especially important to consider the literature in its entirety when making pronouncements about health effects. Efforts are needed by all to reduce the public confusion by adapting standardized approaches to the reporting of data. This paper provides a framework for both standardization of nomenclature and appropriate interpretation of data.