Effect of Circulating Forms of Soy Isoflavones on the Oxidation of Low Density Lipoprotein

Turner, Rufus; Baron, Tobias; Wolffram, Siegfried; Minihane, Anne Marie; Cassidy, Aedín; Rimbach, Gerald; Weinberg, Peter D.

doi:10.1080/10715760310001641854

Cited by 76 publications

(51 citation statements)

References 25 publications

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“…The frequency of isoflavone consumption has no effect on the proportion of glucuronides, sulfates and aglycones of genistein and daidzein in plasma or urine (Zhang et al 2003). The relative biological activities of the isoflavone conjugates in the plasma are dependent on the chemical structure (Turner et al 2004).…”

Section: Bioavailability and Sourcesmentioning

confidence: 99%

Critical review of health effects of soyabean phyto-oestrogens in post-menopausal women

et al. 2006

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A consensus view of soyabean phyto-oestrogens in clinical interventions in post-menopausal women is presented that is based on data from the EU-funded project Phytohealth. The phytooestrogens, primarily genistein and daidzein, were given as soyabean-protein isolates, wholesoyabean foods or extracts, supplements or pure compounds. A comprehensive literature search was conducted with well-defined inclusion or exclusion criteria. For areas for which substantial research exists only placebo-controlled double-blind randomised controlled trials (RCT) conducted on healthy post-menopausal women were included. For emerging areas all available human studies in post-menopausal women were reviewed. In order to make cross comparisons between studies the doses of isoflavones were calculated as aglycone equivalents. There is a suggestion, but no conclusive evidence, that isoflavones from the sources studied so far have a beneficial effect on bone health. The consumption of whole-soyabean foods and soyabeanprotein isolates has some beneficial effects on lipid markers of cardiovascular risk. The consumption of isolated isoflavones does not affect blood lipid levels or blood pressure, although it may improve endothelial function. For menopausal symptoms there is currently limited evidence that soyabean-protein isolates, soyabean foods or red-clover (Trifolium pratense L.) extract are effective but soyabean isoflavone extracts may be effective in reducing hot flushes. There are too few RCT studies to reach conclusions on the effects of isoflavones on breast cancer, colon cancer, diabetes or cognitive function. The health benefits of soyabean phytooestrogens in healthy post-menopausal women are subtle and even some well-designed studies do not show protective effects. Future studies should focus on high-risk post-menopausal women, especially in the areas of diabetes, CVD, breast cancer and bone health. The current interest in soyabean and its phyto-oestrogen component in relation to human health has resulted in a substantial number of publications on the potential clinical efficacy of these compounds to improve health in menopausal women. However, although numerous reviews have been presented, to date a consensus on the potential importance of these compounds for menopausal health following a critical grading of the studies and their results has not been conducted. The focus of the current review is specifically to grade the evidence from clinical studies addressing the effects of intervention of soyabean isoflavones (for chemical structures of the aglycones, seeAbbreviations: RCT, randomised controlled trial; SPI, soyabean-protein isolate.

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Section: Bioavailability and Sourcesmentioning

confidence: 99%

Critical review of health effects of soyabean phyto-oestrogens in post-menopausal women

et al. 2006

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“…Consequently, their physiologic behavior is likely to be different from that of the native compounds. It has been shown that glucuronidation reduces the biological activities of daidzein and genistein and the genistein sulfation decreases its antioxidant activity as well as its effect on platelet aggregation, inflammation, cell adhesion, and chemotaxis (Rimbach et al, 2003;Turner et al, 2004).…”

Section: Diet Diet Dietmentioning

confidence: 99%

Nutritional flavonoids impact on nuclear and extranuclear estrogen receptor activities

Galluzzo

Marino

2006

Genes Nutr

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“…The activities were comparable to that of genistein; however, cis-and trans-4-hydroxy-equol were less cytotoxic. Regarding the antioxidant activity, it has been shown that equol is more potent than genistein or daidzein and that the hydroxylated metabolites of genistein and daidzein exert an even higher antioxidant efficacy than equol (Arora et al, 1998;Rimbach et al, 2003;Turner et al, 2004). Therefore, studies on the antioxidant capacity of the hydroxylated equol metabolites seem to be interesting.…”

Section: Discussionmentioning

confidence: 99%

“…Equol can act as an anti-androgen by binding 5␣-dihydrotestosterone with high affinity, which prevents 5␣-dihydrotestosterone from binding the androgen receptor (Lund et al, 2004). Furthermore, equol has superior antioxidant properties compared with all other isoflavones (Arora et al, 1998;Turner et al, 2004).…”

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confidence: 99%

Structural Elucidation of Hydroxylated Metabolites of the Isoflavan Equol by Gas Chromatography-Mass Spectrometry and High-Performance Liquid Chromatography-Mass Spectrometry

Rüfer¹,

Glatt²,

Kulling³

2005

Drug Metab Dispos

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ABSTRACT:Equol has, as have other isoflavonoids, recently gained considerable interest due to its possible health effects. However, detailed studies on the metabolism of equol are scarce. Therefore, we investigated the phase I metabolism of equol using liver microsomes from Aroclor-treated male Wistar rats as well as from a male human. The identification of the metabolites formed was elucidated using high performance liquid chromatography (HPLC) with diode array detection, HPLC/atmospheric pressure ionization electrospray mass spectrometry, and gas chromatography-mass spectrometry, as well as reference compounds. (؎)-Equol was converted to 11 metabolites by the liver microsomes from Aroclorpretreated rats comprising three aromatic monohydroxylated and four aliphatic monohydroxylated as well as four dihydroxylated products. The main metabolite was identified as 3-hydroxy-equol. Using human liver microsomes, equol was converted to six metabolites with 3-hydroxy-and 6-hydroxy-equol as main products. Furthermore, the aliphatic hydroxylated metabolite 4-hydroxyequol, which was recently detected in human urine after soy consumption, was formed. On the basis of these findings, it is suggested that phase I metabolism of equol is part of a complex biotransformation of the soy isoflavone daidzein in humans in vivo.

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Effect of Circulating Forms of Soy Isoflavones on the Oxidation of Low Density Lipoprotein

Cited by 76 publications

References 25 publications

Critical review of health effects of soyabean phyto-oestrogens in post-menopausal women

Critical review of health effects of soyabean phyto-oestrogens in post-menopausal women

Nutritional flavonoids impact on nuclear and extranuclear estrogen receptor activities

Structural Elucidation of Hydroxylated Metabolites of the Isoflavan Equol by Gas Chromatography-Mass Spectrometry and High-Performance Liquid Chromatography-Mass Spectrometry

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