Influence of 10 wk of soy consumption on plasma concentrations and excretion of isoflavonoids and on gut microflora metabolism in healthy adults

Wiseman, Helen; Casey, Karen; Bowey, Elizabeth A.; Duffy, Rosanna; Davies, Margaret; Rowland, Ian; Lloyd, Antony S.; Murray, Alistair; Thompson, Richard; Clarke, Don

doi:10.1093/ajcn/80.3.692

Cited by 120 publications

(78 citation statements)

References 30 publications

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“…It is important to note that the concentration of genistein (10 lM) which showed to be antimutagenic in the present study was beyond the concentrations of genistein or daidzein normally obtained in plasma of humans consuming isoflavone containing diets (less than 1-5 lM) (Maubach et al 2003;Safford et al 2003;Wiseman et al 2004). However, intake of an aglycone isoflavone supplement (containing 450 mg genistein, 300 mg daidzein, and other isoflavones daily for 6 months) in a group of 53 prostate cancer patients displayed high plasma levels of genistein (39.85lM) and daidzein (45.59 lM) (deVere White et al 2010).…”

Section: Discussionmentioning

confidence: 57%

Chemoprotective activity of the isoflavones, genistein and daidzein on mutagenicity induced by direct and indirect mutagens in cultured HTC cells

et al. 2012

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Isoflavones are phenolic compounds widely distributed in plants and found in a high percentage in soybeans. They have important biological properties and are regarded as potential chemopreventive agents. The aim of this study was to verify the preventive effect of two soy isoflavones (genistein and daidzein) by a micronucleus assay, analysis of GST activity, and real-time RT-PCR analysis of GSTa2 gene expression. Mutagens of direct (doxorubicin) and indirect (2-aminoanthracene) DNA damage were used. Hepatoma cells (HTC) were treated with genistein or daidzein for 26 h at noncytotoxic concentrations; 10 lM when alone, and 0.1, 1.0 and 10 lM when combined with genotoxic agents. The micronucleus test demonstrated that both isoflavones alone had no genotoxic effect. Genistein showed antimutagenic effects at 10 lM with both direct and indirect DNA damage agents. On phase II enzyme regulation, the current study indicated an increase in total cytoplasmic GST activity in response to genistein and daidzein at 10 lM supplementation. However, the mRNA levels of GSTa2 isozymes were not differentially modulated by genistein or daidzein. The results point to an in vitro antimutagenic activity of genistein against direct and indirect DNA damage-induced mutagenicity.

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Section: Discussionmentioning

confidence: 57%

Chemoprotective activity of the isoflavones, genistein and daidzein on mutagenicity induced by direct and indirect mutagens in cultured HTC cells

et al. 2012

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“…Plasma levels of genistein range from 2 to 5 ng/ml (7-18 nM) in individuals consuming standard Western diets, and are considerably higher in individuals consuming vegetarian diets (0.04-0.09 lM) or high soy diets (0.27-1.2 lM) [Safford et al, 2003]; although circulating serum levels may not reflect tissue uptake of genistein in endocrine-responsive tissues [Chang et al, 2000]. In human feeding studies, consumption of high-soy diets for 10 weeks yielded plasma levels of genistein of 700 nM with large interindividual variation [Wiseman et al, 2004]. Dietary supplementation with a purified genistein-daidzein-glycitein ''bullet'' that delivers genistein amounts 3-to 4-fold greater than a soy-rich Japanese diets yielded plasma genistein levels in humans up to 27 lM, with minimal reported DNA toxicity [Bloedon et al, 2002;Miltyk et al, 2003].…”

Section: Discussionmentioning

confidence: 99%

Modulation of gene methylation by genistein or lycopene in breast cancer cells

King-Batoon

Leszczyńska

Klein

2008

Environ and Mol Mutagen

209

113

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Dietary agents with chemopreventive potential, including soy-derived genistein and tomato-derived lycopene, have been shown to alter gene expression in ways that can either promote or potentially inhibit the carcinogenic processes. To begin to explore the mechanisms by which these agents may be acting we have examined the DNA methylation modulating capacity of genistein or lycopene for several genes relevant to breast cancer in the breast cancer cell lines MCF-7 and MDA-MB-468, as well as in immortalized but noncancer fibrocystic MCF10A breast cells. We find using methylation specific PCR (MSP) that a low, nontoxic concentration of genistein (3.125 lM, resupplemented every 48 hr for 1 week) or a single dose of lycopene (2 lM) partially demethylates the promoter of the GSTP1 tumor suppressor gene in MDA-MB-468 cells. RT-PCR studies confirm a lack of GSTP1 expression in untreated MDA-MB-468, with restoration of GSTP1 expression after genistein or lycopene treatment. The RARb2 gene however, was not demethylated by genistein or lycopene in either of these breast cancer cell lines. But, lycopene (2 lM, once per week for 2 weeks) did induce demethylation of RARb2 and the HIN-1 genes in the noncancer MCF10A fibrocystic breast cells. These data show for the first time that the tomato carotenoid lycopene has direct DNA demethylating activity. In summary, both genistein and lycopene, at very low, dietarily relevant concentrations can potentially mitigate tumorigenic processes via promoter methylation modulation of gene expression. Environ. Mol. Mutagen. 49:36-45, 2008.

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“…24,27,28 Although intestinal microflora was strongly suggested to be involved in equol production from daidzein, on the basis of the results of fecal culture, the intestinal bacteria responsible for daidzein metabolism have not been determined definitively. 26,[29][30][31][32][33][34][35] In our series of studies on the relation between isoflavones and prostate cancer, we have made the following conclusions. (1) The serum levels of equol can categorize the examinees into equol producers and equal non-producers.…”

Section: Discussionmentioning

confidence: 99%

Age-stratified serum levels of isoflavones and proportion of equol producers in Japanese and Korean healthy men

Fujimoto

Tanaka

Hirao

et al. 2008

Prostate Cancer Prostatic Dis

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Racial differences in the incidence of prostate cancer are manifest worldwide, possibly due to the different dietary habits. To elucidate the relationship between the recent trend of phytoestrogenic isoflavone intake and the increased incidence of prostate cancer in Japan, we conducted an agestratified dietary survey of soybean foods in 102 Japanese healthy men (age range: 10-59 years) and measured the serum isoflavones and equol levels in them and 100 Korean healthy men. The intergroup comparison among the age-stratified groups showed significant differences in the daily intake of genistein and daidzein between the teenager group and the other groups of age^30 years (Po0.05). In the Japanese study, the proportion of equol producers in the teenager group was 10%, being significantly the lowest among the age-stratified groups. The proportions of equol producers in the age-stratified groups from 10 to 49 years were also significantly lower than those in the fifties. The equol non-producers consumed significantly less amounts of isoflavones than the equol producers. In the Korean study, the proportions of equol producers were 45% in the teenager and 40% in the twenties and thirties, being significantly lower than in the forties (80%) and fifties (65%). The decreased intake of isoflavones, low serum level of equol and low incidence of equol production in the young generation may become potential risk factors for prostate cancer not only in Japan but also in Korea in the near future. Elucidating the mechanism of equol production may be promising in developing strategies for chemoprevention against prostate cancer.

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Influence of 10 wk of soy consumption on plasma concentrations and excretion of isoflavonoids and on gut microflora metabolism in healthy adults

Cited by 120 publications

References 30 publications

Chemoprotective activity of the isoflavones, genistein and daidzein on mutagenicity induced by direct and indirect mutagens in cultured HTC cells

Chemoprotective activity of the isoflavones, genistein and daidzein on mutagenicity induced by direct and indirect mutagens in cultured HTC cells

Modulation of gene methylation by genistein or lycopene in breast cancer cells

Age-stratified serum levels of isoflavones and proportion of equol producers in Japanese and Korean healthy men

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