Comparison of hormonal activity of isoflavone-containing supplements used to treat menopausal complaints.
OBJECTIVE
The isoflavones present in red clover and soy are used as an alternative treatment for menopausal complaints and are commercially available as high-dose food supplements. These preparations contain varying amounts of active ingredients, often without detailed specifications. Thus, it is difficult to derive a recommended daily dose, and the reliability of these products is rather low.


METHODS
We quantified the isoflavone content of 19 different isoflavone-containing preparations and compared their binding and transactivational activities with regard to estrogen receptor alpha, estrogen receptor beta, androgen receptor, progesterone receptor, peroxisome-proliferator-activated receptor, and aryl hydrocarbon receptor.


RESULTS
The food supplements that we tested bound to and transactivated both the estrogen receptors and the other receptors. After comparing the isoflavone content quantified by us with the isoflavone content specified on the package labels, we found that at least the specified isoflavone content or more could be detected in only 5 of the 19 food supplements that we tested.


CONCLUSIONS
Preparations containing isoflavones should be standardized for the isoflavone aglycone content to facilitate the prediction of theoretical hormonal activity, facilitate the intake of a controlled amount of isoflavones, and ensure greater product reliability.
Department of Biotechnology, University of Natural Resources and Applied Life Sciences, Vienna, Austria.
Evelyne
E
Reiter
Verena
V
Beck
Svjetlana
S
Medjakovic
Monika
M
Mueller
Alois
A
Jungbauer
D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D019587:Dietary Supplements / Q000032:analysis* / Q000592:standards / Q000600:supply & distribution; D047628:Estrogen Receptor alpha / Q000187:drug effects; D047629:Estrogen Receptor beta / Q000187:drug effects; D005260:Female; D005515:Food Labeling / Q000592:standards; D005960:Glucosides / Q000032:analysis; D006801:Humans; D007529:Isoflavones / Q000032:analysis* / Q000378:metabolism / Q000627:therapeutic use; D008593:Menopause / Q000187:drug effects*; D018673:Nutrition Policy; D009753:Nutritive Value; D047492:Peroxisome Proliferator-Activated Receptors / Q000187:drug effects; D008517:Phytotherapy / Q000592:standards; D011944:Receptors, Androgen / Q000187:drug effects; D018336:Receptors, Aryl Hydrocarbon / Q000187:drug effects; D011980:Receptors, Progesterone / Q000187:drug effects; D000077185:Resveratrol; D045730:Soy Foods / Q000032:analysis*; D013267:Stilbenes / Q000032:analysis; D015533:Transcriptional Activation; D029921:Trifolium / Q000737:chemistry*
D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D005960:Glucosides; D007529:Isoflavones; D047492:Peroxisome Proliferator-Activated Receptors; D011944:Receptors, Androgen; D018336:Receptors, Aryl Hydrocarbon; D011980:Receptors, Progesterone; D013267:Stilbenes; C526426:calycosin-7-O-beta-D-glucoside; C040641:genistin; C013908:daidzin; D000077185:Resveratrol