Is soy (Glycine) really richer in isoflavones ,as soy-sponsored studies indicate, than Phaseolus beans? Perhaps I am blind to possible errors in the Kaufmann et al paper, showing many legumes as better sources. So far, I am not convinced that soy is a better source of isoflavones than several other edible legumes consumed both here and the orient. What's the truth??? Whether you praise or condemn the isoflavones, we need to know the truth. Jim Duke
Abstract: The content of 9 types of isoflavonoids (daidzein, glycitein, genistein, formononetin, biochanin A, coumestrol, daidzin, glycitin andgenistin) in 34 domestic or imported raw beans including soybeans, 7 immature beans and 5 bean sprouts consumed in Japan were systematically analyzed. Each isoflavonoid was analyzed in total after acid hydrolysis to the aglycone, and intact individual isoflavonoids were also analyzed without hydrolysis. After the sample clean up, daidzein, glycitein, genistein, formononetin, biochanin A, daidzin, glycitin and genistin were determined by HPLC with a diode array detector and coumestrol was determined by spectrofluorimetry. The content and composition of isoflavonoids varied greatly between soybean sprouts, immature soybeans and mature beans of the same type but of different source. Isoflavonoid content was highest in mature soybeans. The composition of isoflavonoids differed in each growth stage of soybeans. In other beans, the largest content of isoflavonoids was found in mature chickpeas, but this value was less than 1/27 of the isoflavonoid content in mature soybeans. Thus, the contribution of beans other than soybeans to the daily intake of isoflavonoids in a Japanese diet is negligible. [References: 26] Dear Dr. Wiseman I'm preparing to enter your data from your Table 2 on the whole soybean, both as fresh weight (62%
moisture) and calculated zero-moisture basis. (multiplied by 2.5, rounded to 60% moisture). I wonder but what the higher counts for daidzein and genistein (exceeding the counts in soy)for non soy legumes presented by Kaufman et al (1997) may seem so much higher because their analyses may possibly have included the glucoconjugates and aglycones. But if that is the case, the proportionate ratios should still be the same. I don't fully understand how your and the Liggins et al papers you cite still maintain that soy is richer than the other legumes, contrary to what was reported by Kaufman et al. (1997) [ after psoralea (> 1,500 ppm daidzein plus genistein) and pueraria root (more than 300 ppm; not really all that delectable either), we have black turtle bean and yellow split pea at 45, baby lima beans at 40, large lima beans at 35, anasazi and kidney beans at 30 with lentils right there with soy, formerly and erroneously championed as a unique source of genistein, at ca 25 ppm. (Kaufmann et al, 1997].(See table at end of e-mail) Since sprouts that are fungally infected often increase their isoflavone
(fungicidal) content 100- fold, I wonder if dirty mungbean (with fungus, like most homegrown sprouts) sprouts may contribute more estrogenic isoflavones to the oriental diet than soybean. "It is likely that soy phytosetrogens also protect against bowel cancer, heart disease, menopausal symptoms, and osteoporosis." Do you mean that all isoflavones, or just soy isoflavones (p. 1404) "are ligands for both the ERalpha and the ERbeta estrogen receptors, with genistein showing preferential binding to ERbeta. The predominant isoflavones genistein, daidzein, and glycitein occur mainly as glucoconjugates in soybeans and consequently in a wide range of soy-derived foods and to a lesser extent in other legumes...[T]here are other significant non-soy sources of isoflavones, including sprouted beans,, herbs and spice mixes...Some of these individual items can contain 500 mg of genistein kg... The total isoflavone aglycon and glucoside content of soybeans is generally in the range of 1000-4000 mg kg." But the authors tabulate for soybeans mg/kg wet weight (62% moisture). The relative estrogenic potency of the soy isoflavone aglycons in glycitein , genisteinm, daidzein.
DAIDZIN 457- 1,140 ppm ZMB JAF50:1404 DAIDZEIN 5 mg/kg or 13 ppm ZMB JAF50:1404 6-ACETYLDAIDZIN 18 mg/kg or 45 ppm ZMB JAF50:1404 6-MALONYMDAIDZIN 117 mg/kg or 290 ppm ZMB JAF50:1404 GENISTIN 436 mg/kg or 1090 ppm ZMB JAF50:1404 GENISTEIN 3 mg/kg or 8 ppm ZMB JAF50:1404 6-ACETYL-GENISTIN 37 mg/kg or 90 ppm ZMB JAF50:1404 6-MALONYL-GENISTIN 156 mg/kg or 390 ppm ZMB JAF50:1404 GLYCITIN 50 mg/kg or 125 ppm ZMB JAF50:1404 GLYCITEIN 1 mg/kg or 2.5 ppm ZMB JAF50:1404 6-ACETYLGLYCITIN 2 mg/kg or 5 ppm ZMB JAF50:1404 6-MALONYLGLYCITIN 15 mg/kg or 38 ppm ZMB JAF50:1404 TOTAL 1297-6485 Wiseman H, Casey K, Clarke DB, Barnes KA, Bowey E. 2002. Isoflavone Aglycon and Glucoconjugate Content of High- and Low-Soy U.K. Foods Used in Nutritional Studies. J Agric Food Chem 2002 Mar 13;50(6):1404-1410. The isoflavone aglycon and glucoconjugate content of commercially prepared and
"home- prepared" high- and low-soy foods selected for use in an on-going nutritional study were measured by LC-MS. The daidzin, daidzein, 6"-O-malonyldaidzin, 6"-O-acetyldaidzin, genistein, genistin, 6"-O-malonylgenistin, 6"-O- acetylgenistin, glycitin, glycitein, 6"-O-malonylglycitin, and 6"-O-acetylglycitin content are expressed in terms of individual isoflavones, total isoflavone equivalents, and milligrams of isoflavones per portion served. Soybeans (774 mg kg(-)(1) total isoflavones) and soybean- containing foods had the highest isoflavone content of the foods examined. The low-soy foods all contained very low concentrations (<8 mg kg(-)(1) total isoflavones) of the isoflavone aglycons and glucoconjugates. High- and low-soy 11 day rotating menus were constructed from the analyzed foods to deliver 100.0 and 0.5 mg of isoflavones per day, respectively. PMID11879011 Compared to one soy variety with 24 ppms genistein, yellow split peas had 46, black turtle beans 45, baby lima beans 40, large lima beans 34, anasazi beans 30, red kidney beans 29, and red lentils 25, black eyes peas 22, pinto beans 22, mung beans 22, azuki beans 21, 2. and faba bean 18, making soy seem more average than superlative, as far as genistein in this report is concerned. (on a dry weight basis) Kaufman,PB , Duke, JA Brielmann, H, Boik, J and Hoyt JE 1997. A Comparative Survey of Leguminous Plants as Sources of the Isoflavones Genistein and
Daidzein: Implications For Human Nutrition and Health. Journal of Alternative & Complementary Medicine 3(1): 7-12. James A. "Jim" Duke Botanical Consultant Herbal Vineyard, Inc. 8210 Murphy Road Fulton, MD 20759