Evidence for lack of absorption of soy isoflavone glycosides in humans, supporting the crucial role of intestinal metabolism for bioavailability

Setchell, Kenneth D.R.; Brown, Nesbitt D.; Zimmer-Nechemias, Linda; Brashear, Wayne T.; Wolfe, Brian; Kirschner, Abby S.; Heubi, James E.

doi:10.1093/ajcn/76.2.447

Cited by 537 publications

(421 citation statements)

References 49 publications

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“…In soybean foods, isoflavones exist in the aglycone (genistein, daidzein, and glycitein) and glucoside forms (Richelle et al, 2002;Setchell et al, 2002). When soybeans are taken in, glucoside forms are hydrolyzed into absorbable aglycones.…”

Section: Introductionmentioning

confidence: 99%

Counts of Slackia sp. strain NATTS in Intestinal Flora are Correlated to Serum Concentrations of Equol both in Prostate Cancer Cases and Controls in Japanese Men

Sugiyama¹,

Nagata²,

Fukuta³

et al. 2014

Asian Pacific Journal of Cancer Prevention

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Background: Isoflavones, which are included in soybeans, have been suggested to protect against prostate cancer. Equol, one of isoflavones, is an intestinally derived bacterial metabolite of daidzein. A newly identified equol-producing bacterium, Slackia sp. strain NATTS, with a high equol-producing activity was isolated from human feces in Japanese adults. Counts of Slackia sp. strain NATTS in intestinal flora have not been assessed with regard to prostate cancer risk. In this study, we investigated the association of serum isoflavones and counts of Slackia sp. strain NATTS with prostate cancer risk in a case-control study. Materials and Methods: Concentrations of isoflavones and counts of Slackia sp. strain NATTS in feces were measured from 44 patients with prostate cancer and 28 hospital controls. The risk of prostate cancer was evaluated in terms of odds ratios (ORs) and 95% confidence intervals (CIs) by the logistic regression analysis. Results: The detection proportions of Slackia sp. strain NATTS in cases and controls were 34.1% and 25.0%, respectively. Counts of Slackia sp. strain NATTS were significantly correlated with serum concentrations of equol both in cases and controls (Spearman correlation coefficients, r s =0.639 and r s =0.572, p<0.01, respectively). Serum concentrations of genistein, daidzein, glycitein, and equol were not significantly associated with risk of prostate cancer. Conclusions: This study found that counts of Slackia sp. strain NATTS correlated with serum concentrations of equol both in prostate cancer cases and controls, but serum isoflavone concentrations were not associated with risk of prostate cancer in our patients.

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Section: Introductionmentioning

confidence: 99%

Counts of Slackia sp. strain NATTS in Intestinal Flora are Correlated to Serum Concentrations of Equol both in Prostate Cancer Cases and Controls in Japanese Men

Sugiyama¹,

Nagata²,

Fukuta³

et al. 2014

Asian Pacific Journal of Cancer Prevention

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“…Phytoestrogens are present in foods primarily as their b-glucoside conjugates, which are not absorbed by the body (Setchell et al, 2002b). Both isoflavone and lignan glucosides undergo significant metabolism in the intestines by colonic microflora to produce their aglucones (Day et al, 1998;Rowland et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Urinary phytoestrogen concentrations in the U.S. population (1999–2000)

Valentín-Blasini

Sadowski

Walden

et al. 2005

J Expo Sci Environ Epidemiol

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We report population-based urinary concentrations of phytoestrogens stratified by age, sex, and composite racial/ethnic variables. We measured the isoflavones F genistein, daidzein, equol, and O-desmethylangolensin (O-DMA) F and the lignans F enterolactone and enterodiol F in approximately 2500 urine samples from individuals aged 6 years and older who participated in the National Health and Nutrition Examination Survey (NHANES) in 1999 and 2000. We detected all phytoestrogens in over 70% of the samples analyzed; enterolactone was detected in the highest concentrations, and daidzein was detected with the highest frequency. The geometric means for each phytoestrogen were as follows: genistein, 22.3 mg/g; daidzein, 68.6 mg/g; equol, 7.65 mg/g; O-DMA, 3.95 mg/g; enterolactone, 217 mg/g; and enterodiol, 24.3 mg/g creatinine. The 95th percentiles for each phytoestrogen were as follows: genistein, 380 mg/g; daidzein, 944 mg/g; equol, 50.3 mg/g; O-DMA, 217 mg/g; enterolactone, 2240 mg/g; and enterodiol, 240 mg/g creatinine. Multivariate analyses showed statistically significant differences among many of the demographic subgroups. Adolescents had higher concentrations of genistein and equol than adults. Non-Hispanic whites had higher concentrations of enterodiol and equol than Mexican Americans or non-Hispanic blacks. Non-Hispanic whites also had higher concentrations of enterolactone and O-DMA than Mexican Americans. Mexican Americans had higher concentrations of genistein than non-Hispanic blacks; however, the opposite was found for O-DMA. Determination of phytoestrogen exposure in the US population will help us to better understand phytoestrogen consumption in the US and will assist us in elucidating the potential role of phytoestrogens in protecting against cancer and heart disease.

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“…The increased plasma isoflavone levels in subjects given the isoflavone preparation is an important finding, as there have been several reports of significant variation in absorption of isoflavones in the literature and thus bioavailability (37)(38)(39)(40). Based on these controversial reports, we paid special attention to dose, multidose regimen to provide a consistent dose per day and the aglycone formulation of the purified isoflavones in this study.…”

Section: Discussionmentioning

confidence: 99%

A Phase II Randomized, Placebo-Controlled Clinical Trial of Purified Isoflavones in Modulating Steroid Hormones in Men Diagnosed With Localized Prostate Cancer

Kumar

Krischer

Allen

et al. 2007

Nutrition and Cancer

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Our purpose was to evaluate the safety and effectiveness of purified isoflavones in producing an increase in plasma isoflavones and a corresponding change in serum sex hormone binding globulin (SHBG) and steroid hormone levels in men diagnosed with early stage prostate cancer. In this Phase II randomized, double-blinded, placebo-controlled trial, 53 prostate cancer patients with a Gleason score of 6 or below were supplemented with 80 mg purified isoflavones or placebo for 12 weeks. Changes in plasma isoflavones, serum steroid hormones, and safety markers were analyzed from baseline to 12 wk. A total of 50 subjects completed the study. Although significant increases in plasma isoflavones (P < 0.001) was observed with no clinical toxicity, the corresponding modulation of serum SHBG, total estradiol, and testosterone in the isoflavone-treated group compared to men receiving placebo was nonsignificant. Increasing plasma isoflavones failed to produce a corresponding modulation of serum steroid hormone levels in men with localized prostate cancer. The study establishes the need to explore other potential mechanisms by which prolonged and consistent purified isoflavone consumption may modulate prostate cancer risk.

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Evidence for lack of absorption of soy isoflavone glycosides in humans, supporting the crucial role of intestinal metabolism for bioavailability

Abstract: Isoflavone glycosides are not absorbed intact across the enterocyte of healthy adults, and their bioavailability requires initial hydrolysis of the sugar moiety by intestinal beta-glucosidases for uptake to the peripheral circulation.

Cited by 537 publications

References 49 publications

Counts of Slackia sp. strain NATTS in Intestinal Flora are Correlated to Serum Concentrations of Equol both in Prostate Cancer Cases and Controls in Japanese Men

Counts of Slackia sp. strain NATTS in Intestinal Flora are Correlated to Serum Concentrations of Equol both in Prostate Cancer Cases and Controls in Japanese Men

Urinary phytoestrogen concentrations in the U.S. population (1999–2000)

A Phase II Randomized, Placebo-Controlled Clinical Trial of Purified Isoflavones in Modulating Steroid Hormones in Men Diagnosed With Localized Prostate Cancer

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