Dangers of Dietary Isoflavones At Levels Above Those Found In Traditional Diets
Cargill has received "self-determined" GRAS status for its AdvantaSoyTMClearTM isoflavone supplement to be used as an additive for beverages, nutrition bars, yoghurt, meal replacements and confections. The summaries of studies below provide ample proof of the dangers of adding phytoestrogens (isoflavones) to common foods. Deleterious effects include endocrine disruption, thyroid suppression, immune system suppresion, suppression of sperm production, DNA breakage and increased incidence of leukemia, breast cancer, colon cancer, infertility, growth problems and subtle changes in sexually dimorphic behaviors.
It has been argued that high levels of soy isoflavones such as genistein, daidzein and genistin in Asian diets protect the inhabitants of Japan and China from certain degenerative diseases, especially breast and prostate cancer. Actually, consumption of soy in traditional Asian diets is low. A 1975 report lists soyfoods as minor sources of protein in Japan and China.1 Major sources of protein listed were meat including organ meats, poultry, fish and eggs. Average isoflavone consumption in Asian diets ranges from 3-28 mg/day, as shown in the table below.
Studies indicate that isoflavone consumption at levels slightly exceeding those found in tradition diets results in thyroid suppression and endocrine disruption. The AdvantaSoyTMClearTM supplement would add 30-50 mg of isoflavones to a 100-gram serving of various common western foods, levels that exceed the amounts found in traditional diets and that are in the range of levels shown to cause problems, especially for sensitive individuals. Note that this level is also greater than the amount provided by 25 mg soy protein isolate, the amount determined by the FDA to warrant a health claim. It is not only possible but likely that many individuals will consume two or more servings of foods to which the Cargill isoflavones have been added, especially as these foods will be promoted with much advertising touting their health benefits. Two or more servings of such foods would provide 60-100 mg isoflavones per day, an amount that provides the estrogen equivalent of the contraceptive pill2 and one that clearly poses dangers after only a brief period of daily intake.
China (1990 survey)3 3 mg/day
Japan (1996 survey)4 10 mg/day
Japan (1998 survey)5 25 mg/day
Japan (2000 survey)6 28 mg/day
In Japanese subjects receiving adequate iodine, causing thyroid suppression after 3months7 35 mg/day
In American women, causing hormonal changes after 1 month8 45 mg/day
In American women, causing changes presaging breast cancer after 14 days9 45 mg/day
FDA recommended amount10 24 mg/day
AdvantaSoyTMClearTM 30-50 mg/ 100 g serving