title: Supplementation with isoflavonoid phytoestrogens does not alter serum lipid concentrations: a randomized controlled trial in humans.
abstract: Isoflavonoids are a class of flavonoids that are derived in the human diet mainly from soybean-based foods. The major dietary isoflavonoids, genistein and daidzein, have estrogen-like activity and are classed as phytoestrogens. Because estrogens can lower serum LDL cholesterol and raise HDL cholesterol, the objective of this study was to determine if isoflavonoids could improve serum lipids in healthy subjects. Forty-six men and 13 postmenopausal women not receiving hormone replacement therapy completed a randomized, double-blind, placebo-controlled trial of two-way parallel design and 8 wk duration. One tablet containing 55 mg of isoflavonoids (predominantly in the form of genistein) or one placebo tablet was taken daily with the evening meal. Subjects maintained their usual diet and physical activity, which were unchanged throughout the intervention. Measurement of isoflavonoids and their metabolites in 24-h urine samples provided an assessment of compliance and of isoflavonoid metabolism. Serum total, LDL, HDL and HDL subclass cholesterol, triglycerides and lipoprotein (a) were assessed at baseline and during the last week of intervention. After adjustment for baseline values, no significant differences in postintervention serum lipid and lipoprotein (a) concentrations between groups were identified. Further adjustment for age, gender and weight change did not alter the results. In addition, changes in urinary isoflavonoids were not significantly correlated with changes in serum lipids and lipoprotein (a). Therefore, this study does not support the hypothesis that isoflavonoid phytoestrogens can improve the serum lipids, at least in subjects with average serum cholesterol concentrations.
authors.affiliation: University of Western Australia Department of Medicine and the Western Australian Heart Research Institute, Royal Perth Hospital, Perth, WA 6001 Australia.
authors.forename: J M
authors.initials: JM
authors.lastname: Hodgson
authors.forename: I B
authors.initials: IB
authors.lastname: Puddey
authors.forename: L J
authors.initials: LJ
authors.lastname: Beilin
authors.forename: T A
authors.initials: TA
authors.lastname: Mori
authors.forename: K D
authors.initials: KD
authors.lastname: Croft
mesh_terms: D000328:Adult; D000368:Aged; D001835:Body Weight; D019587:Dietary Supplements; D004311:Double-Blind Method; D004968:Estrogens, Non-Steroidal / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000494:pharmacology* / Q000652:urine; D008055:Lipids / Q000097:blood*; D008074:Lipoproteins / Q000097:blood; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D048789:Phytoestrogens; D028321:Plant Preparations
chemical_list: D004968:Estrogens, Non-Steroidal; D007529:Isoflavones; D008055:Lipids; D008074:Lipoproteins; D048789:Phytoestrogens; D028321:Plant Preparations