Time-resolved fluoroimmunoassay for equol in plasma and urine

Brouwers, E. E. M.; L'homme, Rafaëlla F. A.; Al‐Maharik, Nawaf; Lapčı́k, Oldřich; Hampl, Richard; Wähälä, Kristiina; Mikola, Heikki; Adlercreutz, Herman

doi:10.1016/s0960-0760(03)00071-2

Cited by 50 publications

(40 citation statements)

References 62 publications

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“…In addition to genistein concentrations, which were measured to assess compliance, equol levels were measured to determine which women were able to metabolize this compound. Genistein and equol concentrations in plasma were measured with TR-FIA kits (Labmaster) as previously described (20). Exposure to a sufficient amount of daidzein is required to assess equol producer status.…”

Section: Methodsmentioning

confidence: 99%

Soy Protein Containing Isoflavones and Mammographic Density in a Randomized Controlled Trial in Postmenopausal Women

Verheus

Gils

Kreijkamp-Kaspers

et al. 2008

Cancer Epidemiology, Biomarkers &Amp; Prevention

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Background: The relatively high dietary intake of soy in Asian countries has been hypothesized to, at least partly, explain the lower breast cancer incidence patterns in these countries compared with the Western world. The aim of the present study was to determine the effect of daily soy supplementation on mammographic density, one of the strongest known risk factors for breast cancer. Methods: A double-blind, randomized, controlled trial was conducted to compare the effects of soy protein intake containing 99 mg isoflavones daily with intake of milk protein (placebo) for the duration of 1 year. Two hundred and two Dutch postmenopausal women ages 60 to 75 years were randomized. Mammographic density was assessed using a quantitative computerassisted method on digitized mammograms. Equol

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Section: Methodsmentioning

confidence: 99%

Soy Protein Containing Isoflavones and Mammographic Density in a Randomized Controlled Trial in Postmenopausal Women

Verheus

Gils

Kreijkamp-Kaspers

et al. 2008

Cancer Epidemiology, Biomarkers &Amp; Prevention

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“…Urine was analyzed for equol by competitive time-resolved fluoroimmunoassay as previously described (Brouwers et al, 2003). Intra-assay coefficients of variation were between 3.4 and 6.9%, and inter-assay coefficients of variation were between 7.4 and 7.7%, at three different concentration levels.…”

Section: Methodsmentioning

confidence: 99%

“…Intra-assay coefficients of variation were between 3.4 and 6.9%, and inter-assay coefficients of variation were between 7.4 and 7.7%, at three different concentration levels. The values were corrected by a formula to correspond to values obtained by reference gas chromatographic-mass spectrometric methods and mean recoveries were 94.3% (Brouwers et al, 2003).…”

Section: Methodsmentioning

confidence: 99%

Consumption of Lactobacillus acidophilus and Bifidobacterium longum do not alter urinary equol excretion and plasma reproductive hormones in premenopausal women

et al. 2004

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Objective: To confirm the results of an earlier study showing premenopausal equol excretors to have hormone profiles associated with reduced breast cancer risk, and to investigate whether equol excretion status and plasma hormone concentrations can be influenced by consumption of probiotics. Design: A randomized, single-blinded, placebo-controlled, parallel-arm trial. Subjects: In all, 34 of the initially enrolled 37 subjects completed all requirements. Intervention: All subjects were followed for two full menstrual cycles and the first seven days of a third cycle. During menstrual cycle 1, plasma concentrations of estradiol (E 2 ), estrone (E 1 ), estrone-sulfate (E 1 -S), testosterone (T), androstenedione (A), dehydroepiandrosterone-sulfate (DHEA-S), and sex-hormone-binding globulin (SHBG) were measured on cycle day 2, 3, or 4, and urinary equol measured on day 7 after a 4-day soy challenge. Subjects then received either probiotic capsules (containing Lactobacillus acidophilus and Bifidobacterium longum) or placebo capsules through day 7 of menstrual cycle 3, at which time both the plasma hormone concentrations and the post-soy challenge urinary equol measurements were repeated. Results: During menstrual cycle 1, equol excretors and non-excretors were not significantly different with respect to subject characteristics, diet, or hormone concentrations. Significant inverse correlations were found between E 2 and body mass index (BMI) (P ¼ 0.02), SHBG and BMI (P ¼ 0.01), DHEA-S and dietary fiber (P ¼ 0.04), and A and protein:carbohydrate ratio (P ¼ 0.02). Probiotic consumption failed to significantly alter equol excretor status or hormone concentrations during menstrual cycle 3, although there were trends towards decreased concentrations of T (P ¼ 0.14) and SHBG (P ¼ 0.10) in the probiotic group. Conclusions: We were unable to verify a previously reported finding of premenopausal equol excretors having plasma hormone concentrations different from those of nonexcretors. Furthermore, a 2-month intervention with probiotic capsules did not significantly alter equol excretion or plasma hormone concentrations.

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“…Plasma isoflavones (genistein, daidzein, equol and Odesmethylangolensin) were analyzed by competitive timeresolved fluoroimmunoassay as described previously (Wang et al, 2000;L'Homme et al, 2002;Brouwers et al, 2003). Intraassay variability was 6.3, 7.1 and 8.1% and interassay variability was 9.5, 9.9 and 15.2% for genistein, daidzein and equol, respectively.…”

Section: Data Collection and Analysismentioning

confidence: 99%

“…Before urinary equol analysis, urine was thawed, pooled proportionally for a 3-day sample, aliquoted and lyophilized for equol quantification. Urinary equol was analyzed by competitive time-resolved fluoroimmunoassay and a gas chromatography-mass spectrometry conversion factor applied to these values as described previously (Brouwers et al, 2003).…”

Section: Data Collection and Analysismentioning

confidence: 99%

Consumption of isoflavone-rich soy protein does not alter homocysteine or markers of inflammation in postmenopausal women

et al. 2007

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Background/Objective: To investigate the effect of soy protein containing isoflavones on homocysteine (Hcy), C-reactive protein (CRP), soluble E-selectin (sE-selectin), soluble vascular adhesion molecule-1 (sVCAM-1) and soluble intercellular adhesion molecule-1 (sICAM-1). Subject/Methods: In a randomized crossover design, 34 postmenopausal women consumed soy protein isolate (2675 g protein containing 4478 mg isoflavones per day) or milk protein isolate (2675 g protein per day) for 6 weeks each. Fasting blood samples were collected at the end of each diet period and end points analyzed by enzyme-linked immunosorbent assay. Results: Concentrations of Hcy, CRP, sE-selectin, sVCAM-1 and sICAM-1 were not different between soy and milk diet treatments. Results did not differ by equol production status or by baseline lipid concentration. Adjustment for intake of folate and methionine did not alter the Hcy results. Conclusions: These data suggest that decreasing vascular inflammation and Hcy concentration are not likely mechanisms by which soy consumption reduces coronary heart disease risk.

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Time-resolved fluoroimmunoassay for equol in plasma and urine

Cited by 50 publications

References 62 publications

Soy Protein Containing Isoflavones and Mammographic Density in a Randomized Controlled Trial in Postmenopausal Women

Soy Protein Containing Isoflavones and Mammographic Density in a Randomized Controlled Trial in Postmenopausal Women

Consumption of Lactobacillus acidophilus and Bifidobacterium longum do not alter urinary equol excretion and plasma reproductive hormones in premenopausal women

Consumption of isoflavone-rich soy protein does not alter homocysteine or markers of inflammation in postmenopausal women

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