Time-resolved fluoroimmunoassay for equol in plasma and urine

The Association between Plasma Concentration of Phytoestrogens and Hypertension within the Korean Multicenter Cancer Cohort

In order to examine the association between plasma phytoestrogen concentration (genistein, daidzein, equol and enterolactone) and hypertension, we conducted a nested case–control study for 229 hypertension cases including 112 prehypertension and 159 healthy controls derived from the Korean Multi-center Cancer Cohort (KMCC). The concentration of plasma phytoestrogens was measured using time-resolved fluoroimmunoassay. We assessed the association between plasma phytoestrogens and hypertension using logistic regression models using odds ratio (OR) and 95% confidence interval (95%CI). The highest tertile of plasma equol and enterolactone concentration exhibited a significantly decreased risk of hypertension (equol, OR = 0.34, 95%CI 0.20–0.57; enterolactone, OR = 0.32, 95%CI 0.18–0.57), compared with the lowest tertile. Equol and enterolactone showed reduced ORs for prehypertension (the highest tertile relative to the lowest tertile, OR = 0.50, 95%CI 0.26–0.96; OR = 0.38, 95%CI 0.19–0.75, respectively) and hypertension (OR = 0.42, 95%CI 0.22–0.81; OR = 0.28, 95%CI 0.14–0.54, respectively). There was a stronger association in hypertension (the highest tertile relative to the lowest tertile in obesity vs. non-obesity; equol, OR = 0.06 vs. 0.63; enterolactone, OR = 0.07 vs. 0.46; both p-heterogeneity < 0.01). This study suggests that equol and enterolactone may contribute to prevent primarily prehypertension and hypertension, and control cardiovascular disease (CVD) based on the continuum of hypertension and CVD. Further study to assess hypertension risk based on useful biomarkers, including phytoestrogens, may contribute to primary prevention of hypertension.

Kanamycin inhibits daidzein metabolism and abilities of the metabolites to prevent bone loss in ovariectomized mice

BACKGROUND

Daidzein is an isoflavone derived from soybeans that exerts preventive effects on bone loss in ovariectomized (OVX) animals. These effects have been correlated with increasing serum equol levels. In the present study, we investigated the effects of antibiotic intake on equol metabolism from daidzein, and the corresponding levels of bone loss in OVX mice.

METHODS

Eight-week-old female ddY mice (n = 42) were either ovariectomized (OVX) or subjected to a sham operation (sham). OVX mice were then divided into six dietary subgroups: control diet (control), 0.3 % kanamycin diet (KN), 0.1 % daidzein diet (Dz), 0.1 % daidzein and 0.0375 % kanamycin diet (Dz+KN3.75), 0.1 % daidzein and 0.075 % kanamycin diet (Dz+KN7.5), and 0.1 % daidzein and 0.3 % kanamycin diet (Dz+KN30). The mice were fed their respective diets for 4 weeks.

RESULTS

Uterine weight and femoral bone mineral density (BMD) were significantly lower in the OVX mice compared in the sham mice. No significant differences in uterine weight were observed among all OVX dietary subgroups. The Dz subgroup was found to exhibit higher plasma equol and O-desmethylangolensin (O-DMA) concentrations, as well as greater femoral BMD, compared to all other OVX subgroups. Furthermore, when compared to the Dz group, kanamycin intake decreased plasma equol and O-DMA concentrations, as well as femoral BMD in the OVX mice.

CONCLUSIONS

These results suggest that kanamycin intake inhibited the conversion of daidzein to equol and O-DMA, blocking the preventive effects of daidzein on bone loss in OVX mice. Therefore, the bone-protective effects of daidzein intake may be predominantly associated with increased plasma concentrations of either equol or O-DMA.

The combined effects of soya isoflavones and resistant starch on equol production and trabecular bone loss in ovariectomised mice

Equol is a metabolite of the soya isoflavone (ISO) daidzein that is produced by intestinal microbiota. Equol has greater oestrogenic activity compared with other ISO, and it prevents bone loss in postmenopausal women. Resistant starch (RS), which has a prebiotic activity and is a dietary fibre, was reported to promote equol production. Conversely, the intestinal microbiota is reported to directly regulate bone health by reducing inflammatory cytokine levels and T-lymphocytes in bone. The present study evaluated the combined effects of diet supplemented with ISO and RS on intestinal microbiota, equol production, bone mineral density (BMD) and inflammatory gene expression in the bone marrow of ovariectomised (OVX) mice. Female ddY strain mice, aged 8 weeks, were either sham-operated (Sham, n 7) or OVX. OVX mice were randomly divided into the following four groups (seven per group): OVX control (OVX); OVX fed 0·05 % ISO diet (OVX+ISO); OVX fed 9 % RS diet (OVX+RS); and OVX fed 0·05 % ISO- and 9 % RS diet (OVX+ISO+RS). After 6 weeks, treatment with the combination of ISO and RS increased equol production, prevented the OVX-induced decline in trabecular BMD in the distal femur by modulating the enteric environment and altered OVX-induced inflammation-related gene expression in the bone marrow. However, there were no significant differences in bone parameters between the ISO+RS and ISO-alone groups in OVX mice. Our findings suggest that the combination of ISO and RS might alter intestinal microbiota and immune status in the bone marrow, resulting in attenuated bone resorption in OVX mice.

Combined effects of soy isoflavones and milk basic protein on bone mineral density in hind-limb unloaded mice

We examined whether the combination of isoflavone and milk basic protein both are reported to be effective for bone metabolism, prevents bone loss induced by skeletal hind-limb unloading in mice. Female ddY strain mice, aged 8 weeks, were divided into six groups (n = 6–8 each): (1) normally housed group, (2) loading group, (3) hind-limb unloading group fed a control diet, (4) hind-limb unloading group fed a 0.2% isoflavone conjugates diet, (5) hind-limb unloading group fed a 1.0% milk basic protein diet, and (6) hind-limb unloading group fed a 0.2% isoflavone conjugates and 1.0% milk basic protein diet. After 3 weeks, femoral bone mineral density was markedly reduced in unloading mice. The combination of isoflavone and milk basic protein showed cooperative effects in preventing bone loss and milk basic protein inhibited the increased expression of osteogenic genes in bone marrow cells in unloading mice. These results suggest that the combination of soy isoflavone and milk basic protein may be useful for bone health in subjects with disabling conditions as well as astronauts.

Effects of daidzein and kiwifruit on bone mineral density and equol production in ovariectomised rats

In this study, we investigated the synergistic effects of daidzein (Dz) and kiwifruit on bone and equol production in ovariectomised (OVX) rats. Female Sprague-Dawley rats were randomly assigned to one of five groups: sham operated, OVX control, OVX fed 0.1% Dz-supplemented diet (OVX + Dz), OVX fed 0.1% Dz and green kiwifruit (GRK)-supplemented diet (OVX + Dz + GRK) and OVX fed 0.1% Dz and gold kiwifruit (GOK)-supplemented diet (OVX + Dz + GOK). There were no significant differences in whole body and femur bone mineral density (BMD) among groups at week 8. BMD in the OVX group significantly decreased at week 8; however, BMD in the OVX + Dz + GRK was not significantly different from baseline in the end of the study. However, supplementation with kiwifruit did not affect urinary equol concentrations, urinary ratios of equol to Dz and the composition of caecal microbiota. These results suggest that the combination of Dz and GRK may slightly reduce bone loss caused by oestrogen deficiency but does not affect equol production.

Effects of short-term fructooligosaccharide intake on equol production in Japanese postmenopausal women consuming soy isoflavone supplements: a pilot study

BACKGROUND

Recent studies suggest that some of the clinical effectiveness of soy or daidzein, which is a type of isoflavone, may be attributed to a person's ability to produce equol from daidzein. Equol, which is a metabolite of one of the major soybean isoflavones called daidzein, is produced in the gastrointestinal tract by certain intestinal microbiota where present. Habitual dietary patterns may alter the intestinal bacterial profile, and influence the metabolism of isoflavones and the production of equol. Fructooligosaccharides (FOS) have a prebiotic activity as well as being a dietary fibre. The purpose of the present study was to determine whether FOS supplementation increases equol production in equol producers and stimulates equol production in equol non-producers in Japanese postmenopausal women.

METHODS

A soy challenge was used to assess equol-producer status prior to the start of the study in healthy postmenopausal Japanese women. The study involved 4 separate groups in randomised crossover design. First, subjects were classified as equol producers (n = 25) or non-producers (n = 18), and then they were randomly assigned to the FOS or control group. All subjects received a daily dose of 37 mg isoflavone conjugates in the capsule (21 mg aglycone form) and either FOS (5 g/day) or sucrose as control, in a randomised crossover study design. Equol -production was assessed by testing the serum and urine before and after the 2-week supplementation period.

RESULTS

The analyses were conducted on 34 subjects completed the study, 21 (61.8%) were classified as equol producers, and 13 (38.2%) as non-producers. Significant differences were observed in the interaction effect of time × equol state after 1 week of intervention (p = 0.006). However there were no effects after 2 weeks of intervention (p = 0.516). Finally, in both equol producers and non-producers, FOS supplementation did not affect the serum equol concentration or the urinary equol to daidzein concentration ratios.

CONCLUSIONS

We have reported that FOS intervention (5 g/day for 2 weeks) does not significantly modulate the capacity of intestinal microbiota to produce equol in postmenopausal Japanese women, in either equol producers or non-producers in this pilot study. Further larger investigations that explore the roles of specific intestinal microbiota in equol production will enable the establishment of dietary conditions that are required to enhance equol production.

Effects of dietary fibre and tea catechin, ingredients of the Japanese diet, on equol production and bone mineral density in isoflavone-treated ovariectomised mice

Equol is a metabolite of the isoflavone daidzein (Dz) and is produced by the bacterial microflora in the distal intestine and colon. Some epidemiological studies have reported an association between increased equol production and intakes of green tea or dietary fibre, which are ingredients of the standard Japanese diet. We examined the effects of a diet supplemented with Dz and tea catechin or dietary fibre on equol production and bone mineral density in ovariectomised (OVX) mice. Female mice of the ddY strain were either sham operated or OVX. OVX mice were fed a control diet, a 0·1 % Dz-supplemented diet or a 0·1 % Dz diet supplemented with one of the food components commonly consumed in the Japanese diet. The mice were given 1 % tea catechin (w/w) as part of the diet in Expt 1 or 5 % polydextrose (PD) and 5 % raffinose (Raf) (w/w) as part of the diet in Expt 2. Catechin reduced serum equol levels and attenuated the beneficial effect of Dz on femoral bone loss. The soluble dietary fibres PD and Raf stimulated equol production, and enhanced the bone-protective effects of Dz on femoral bone. These results suggest that dietary fibre, in particular, PD, may alter the bioavailability of isoflavones and prevent osteopenia in OVX mice.

Gut metabotypes govern health effects of dietary polyphenols

Polyphenols are thought to be responsible for some of the health effects conferred by a diet rich in fruit and vegetables. Both the formation of bioactive polyphenol-derived metabolites and the modulation of colonic microbiota contribute to these health benefits. Therefore, one cannot infer biological responses from dietary intake records without considering polyphenol-microbiota interactions. However, the latter are complex and subject to large interindividual variability, leading to different polyphenol-metabolizing phenotypes or 'metabotypes'. Based on accurate measurements of intake, exposure and effect on carefully selected samples, the physiological relevance of dietary polyphenols can be evaluated for each metabotype. Ultimately, this will lead to predictive modeling and the development of (personalized) functional foods and other nutraceuticals with maximized health benefits.

Synergistic effect of isoflavone glycosides and fructooligosaccharides on postgastrectomy osteopenia in rats

Fructooligosaccharides stimulate the growth of Bifidobacteria, which cleave isoflavone glycosides to yield corresponding aglycones, and convert metabolites by enhancing enterohepatic recirculation of isoflavones in rats. In the present study, we determined the synergistic effect of dietary isoflavone glycosides and fructooligosaccharides on postgastrectomy osteopenia in rats. Nine-week-old male Sprague-Dawley rats were gastrectomized (n = 20) or sham operated, (control, n = 5) and then randomly assigned to 5 diet groups: sham-a purified diet control, gastrectomized-control, gastrectomized-isoflavone (0.2% isoflavone glycosides), gastrectomized-fructooligosaccharides (7.5% fructooligosaccharides), and isoflavone and fructooligosaccharides (0.2% isoflavone glycosides + 7.5% fructooligosaccharides). After 6 weeks, the rats were killed and biological samples were collected. In gastrectomized rats, fructooligosaccharides prevented femoral bone fragility, but isoflavone without fructooligosaccharides did not inhibit postgastrectomy osteopenia. Isoflavone and fructooligosaccharides exhibited a synergistic in the distal metaphyseal trabecular bone, indicated by peripheral quantitative computed tomography. Moreover, fructooligosaccharides increased calcium absorption and equol production from daidzein in gastrectomized rats. These results indicate that isoflavone alone did not inhibit postgastrectomy osteopenia, but the combination of isoflavone and fructooligosaccharides improved the inhibition of trabecular bone loss by increasing calcium absorption and equol production through fructooligosaccharides supplementation.

Resistant starch promotes equol production and inhibits tibial bone loss in ovariectomized mice treated with daidzein

Daidzein is metabolized to equol in the gastrointestinal tract by gut microflora. Equol has greater estrogenic activity than genistein and daidzein, with its production shown to be promoted by dietary fiber. It is known that resistant starch (RS) is not absorbed in the proximal intestine and acts as dietary fiber in the colon. In this study, we investigated the combined effects of daidzein and RS intake on equol production, bone mineral density, and intestinal microflora in ovariectomized (OVX) mice. Female mice of the ddY strain, aged 8 weeks, were either sham operated (n = 6) or OVX. The OVX mice were randomly divided into 5 groups: OVX control (n = 6), OVX fed 0.1% daidzein-supplemented diet (OVX + Dz, n = 8), OVX fed 0.1% daidzein- and 12% RS-supplemented diet (OVX + Dz + RS, n = 8), OVX fed 12% RS-supplemented diet (OVX + RS, n = 8), and OVX who received daily subcutaneous administration of 17 β-estradiol (n = 6). After 6 weeks, urinary equol concentration was significantly higher in the OVX + Dz + RS group than in the OVX + Dz group. The bone mineral density of the whole tibia was higher in the OVX + Dz +RS group compared with the OVX + Dz group. The occupation ratios of Bifidobacterium spp in the cecal microflora in groups fed RS were significantly higher than those in the other groups. The present study demonstrated that RS may increase the bioavailability of daidzein.

Combined effects of soy isoflavone and fish oil on ovariectomy-induced bone loss in mice

Both soy isoflavone and n-3 polyunsaturated fatty acids are known to reduce the levels of bone-resorbing cytokines; however, the synergistic effects of these food ingredients have not been examined yet. This study was performed to elucidate the effect of concomitant intake of soy isoflavone and fish oil on bone mass in ovariectomized mice. Eight-week-old ddY female mice were subjected to ovariectomy (OVX) or sham surgery, and then fed an AIN-93G with safflower oil (So) as a control lipid source, isoflavone-supplemented safflower oil (So + I), fish oil instead of safflower oil (Fo) or isoflavone-supplemented fish oil (Fo + I) for 4 weeks. Femoral bone mineral density was significantly decreased by OVX; however, this decrease was inhibited by the intake of isoflavone and/or fish oil. Histomorphometric analyses showed that bone volume and trabecular thickness in the distal femoral trabecular bone were significantly lower in the So group than in the sham group, but those were restored in the Fo + I groups. The number of osteoclasts was significantly decreased by isoflavone intake. The increased rate of bone resorption after OVX was inhibited by isoflavone and/or fish oil. The serum concentration of tumor necrosis factor alpha was increased after OVX, but was significantly lower with the combination of isoflavone with fish oil than isoflavone or fish oil alone. The results of this study indicated that the intakes of soy isoflavone and/or fish oil might have ameliorating effects on bone loss due to OVX. Further, the concomitant intake of soy isoflavone and fish oil at a low dose showed better effects on cytokines related with bone resorption.

Development of bioluminescent enzyme immunoassay for s-equol using firefly luciferase and its application to the assessment of equol-producer status

In this study, we developed a specific bioluminescent enzyme immunoassay (BLEIA) for S-equol, employing firefly luciferase as a labeling enzyme, as an alternative to HPLC methods. Satisfactory correlation (r=0.992) was shown when this S-equol BLEIA was compared with HPLC. The cross-reactivity with R-equol as its diastereoisomer is <5%, and that with daidzein, which is the substrate of equol, is 0.02%. Frequencies of Japanese equol producers determined using two distinct approaches were compared: a threshold value for urinary S-equol concentration of 232 ng/ml gave frequencies of 32% of men and 19% of women. These values correspond to the results for log(10)-transformed urinary S-equol to daidzein ratio threshold of -1.75, namely, 34% of men and 19% of women. When the changes in concentration of urinary equol and daidzein were measured after ingestion of isoflavone, the maximum concentration (C(max)) of urinary equol appeared after 9.6 h of isoflavone consumption; this C(max) was 2 h later than that for daidzein. The S-equol BLEIA documented in this study is expected to be an important tool for the assessment of equol producer status and demonstration of the bioavailability of isoflavone.

Suppression of colonic aberrant crypt foci by soy isoflavones is dose-independent in dimethylhydrazine-treated rats

The potential of soy isoflavones (SIs) to reduce colon cancer has been investigated in animal models. These studies have found that outcomes are variable and depend on SI dose. The present study investigated dose-response effects of SIs on colon carcinogenesis in a chemically induced rat cancer model. Sprague-Dawley male rats were injected with 1,2-dimethylhydrazine (DMH) and were provided experimental diets that contained 0, 10, 50, 150, or 500 mg of SI aglycones/kg of diet for 12 weeks. Plasma concentrations of genistein, daidzein, and equol were determined using time-resolved fluoroimmunoassay. Plasma concentrations of these SIs tended to increase in a dose-dependent manner in DMH-treated rats. The numbers of aberrant crypt foci (ACF) and the expression of cyclooxygenase-2 (COX-2) proteins of colons were significantly decreased in the SI-fed groups compared with the control group; however, suppression was not dose-dependent. Furthermore, there were no significant correlations between plasma SI concentrations and ACF or COX-2 expression. Increased SI intake and increased plasma levels of SIs and metabolites were not associated with tissue levels of lipid peroxidation. We conclude that dietary supplementation of SIs suppresses DMH-induced ACF formation and COX-2 expression in a dose-independent manner.

Simultaneous determination of 11 phytoestrogens in human serum using a 2 min liquid chromatography/tandem mass spectrometry method

A rapid 2 min liquid chromatography-tandem mass spectrometry (LC-MS/MS) method operating in multiple reaction ion monitoring mode was developed and validated that allows for the characterization and simultaneous quantification of 11 phytoestrogen metabolites with mass transitions m/z 241/119 (equol), 253/132 (daidzein), 255/149 (dihydrodaidzein), 257/108 (O-desmethylangolesin), 269/133 (genistein), 283/184 (glycitein), 267/191 (formononetin), 289/109 (biochanin A), 267/91 (coumestrol), enterodiol (301/253), and enterolactone (297/253). The method was demonstrated to be specific and sensitive, and a linear response for each phytoestrogen was observed over a range of 1-5000 ng/mL in human serum with the exception of dihydrodaidzein, whose lower limit of quantification was 2 ng/mL. The separation was carried out on a Synergi Polar-RP 2.5 micron (50 mm x 2.0 mm i.d.) column at 50 degrees C with water and acetonitrile (both containing 10 mM ammonium acetate) as the mobile phase under gradient conditions at a flow rate of 0.75 mL/min. This LC-MS/MS method is very useful for high-throughput analysis of phytoestrogens and proved to be simple, sensitive, reproducible, and reliable.

Effect of pure genistein on bone markers and hot flushes

OBJECTIVE

To evaluate the effect of 90 mg of daily genistein on markers of bone turnover and menopausal symptoms.

DESIGN

This was a cross-over, placebo-controlled study involving 100 postmenopausal women. Subjects were randomly assigned to daily genistein or placebo for 6 weeks and crossed over to the alternative preparation for the following 6 weeks. Pure genistein was processed and encapsulated in accordance with British Pharmacopoeia standards. Each capsule contained 90 mg of pure genistein while the placebo contained just the recipients.

RESULTS

In women with significant hot flushes (score (intensity x number) > or = 9), genistein reduced symptoms by 30% compared to baseline and the difference compared to placebo was statistically significant. No effect was observed on biochemical markers of bone turnover, possibly due to the short duration of each arm of the study. Genistein reduced osteocalcin, a marker of bone formation, by 3.6% compared to baseline and 0.31% compared to placebo (p = 0.81 and 0.40, respectively). Genistein increased cross-link telopeptide, a marker of bone resorption, by 1.8% compared to baseline and 0.29% compared to placebo; both differences were not statistically significant (p = 0.078 and 0.88, respectively).

CONCLUSION

Pure genistein at a dose of 90 mg per day appears to reduce the number of hot flushes in postmenopausal women but the effect is mild.

Phenolics: occurrence and immunochemical detection in environment and food

Phenolic compounds may be of natural or anthropogenic origin and be present in the environment as well as in food. They comprise a large and diverse group of compounds that may be either beneficial or harmful for consumers. In this review first a non-exhausting overview of interesting phenolics is given, in particular with regards to their presence in environment and food. For some of these compounds, beneficial, toxicological and/or optionally endocrine disrupting activities will be presented. Further, immunochemical detection and/or isolation methods developed will be discussed, including advantages and disadvantages thereof in comparison with conventional analytical methods such as HPLC, GC, MS. A short overview of new sensor-like methods will also be included for present and future application.

Soy protein containing isoflavones and mammographic density in a randomized controlled trial in postmenopausal women

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 computer-assisted method on digitized mammograms. Equol producer status was assessed in plasma provided at the final visit (soy group) or after a 3-day challenge with soy after the trial was finished (placebo group).

RESULTS

A total of 175 women completed the baseline visits and at least one follow-up visit and were included in the intention-to-treat analyses. For 126 women, both pre- and post-trial mammograms were available. Mammographic density decreased in both study arms, but the decrease did not differ significantly between intervention and placebo groups. Equol producer status did not modify the results.

CONCLUSION

The results of this trial do not support the hypothesis that a diet high in soy protein among postmenopausal women decreases mammographic density.

Comparative activities of daidzein metabolites, equol and O-desmethylangolensin, on bone mineral density and lipid metabolism in ovariectomized mice and in osteoclast cell cultures

Daidzein, a major isoflavone predominantly found in soybean, is mainly metabolized to equol and O-desmethylangolensin (O-DMA) by the human gut microflora. Equol exhibits a stronger estrogenic activity than daidzein, however, only approximately 30% of the population has been identified as equol-producers and there are too few direct evidences of the effects of the other major metabolite, O-DMA on estrogen-deficient status. The purpose of this study is therefore, to compare the effect of both O-DMA and equol on bone and lipid metabolism in vivo and in vitro. For the in vivo study, 8-week-old female mice were assigned to five groups as follows: sham-operated (sham), ovariectomized (OVX), OVX + 0.5 mg/day O-DMA (OVX + O-DMA), OVX + 0.5 mg/day equol (OVX + Eq), and OVX + 0.03 microg/day 17beta-estradiol (OVX + E2) administration. Three weeks after the intervention, O-DMA and equol did not affect uterine atrophy in OVX mice. The bone mineral density (BMD) of the femur was lower in the OVX group than in the sham group. The administration of equol but not O-DMA, maintained BMD through the intervention. Values of whole body fat mass and plasma lipids were lower in the equol and O-DMA treated OVX mice than those in OVX mice. In the in vitro study, equol significantly inhibited the osteoclast formation induced by 1alpha,25(OH)(2)D(3) in a dose-dependent manner in a co-culture system of mouse bone-marrow cells with primary osteoblastic cells. However, O-DMA slightly inhibited osteoclast formation, and the effect was not dose dependent. These results suggest that the effects of O-DMA on bone and lipid metabolism in OVX mice and osteoclast cell cultures are weaker than those of equol.

Dose-response assessment of the anti-cancer efficacy of soy isoflavones in dimethylhydrazine-treated rats fed 6% fructooligosaccharide

We investigated the combinatorial effects of different doses of dietary soy isoflavones (SI) and fructooligosaccharide (FOS) in a rat model of colon cancer. We hypothesized that increased bioavailability of SI metabolites due to dietary FOS may increase production of bioactive equol and affect colon carcinogenesis in a dose-dependent manner. Sprague-Dawley male rats were injected with 12-dimethylhydrazine (DMH) and were provided experimental diets that contained 0, 10, 50, 150, or 500 mg SI per kg of diet and 6% FOS for 12 weeks. The number of aberrant crypt foci (ACF) and the expression of cyclooxygenase-2 (COX-2) in colonic tissues were significantly decreased in the 6% FOS-fed groups compared to the control group. Gut transit time and fecal pH were significantly lower, and fecal concentrations of bifidobacteria were increased with 6% FOS. However, dietary SI supplementation in combination with 6% dietary FOS did not affect ACF formation or COX-2 expression. Plasma equol concentrations were dose-dependently increased by supplementation of SI up to 500 mg/kg of diet. In conclusion, SI supplementation up to 500 mg/kg of diet appeared to have no additive beneficial effects in rats with chemically-induced colon cancer that were fed 6% FOS, although plasma equol was dose-dependently increased.

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

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 (26+/-5 g protein containing 44+/-8 mg isoflavones per day) or milk protein isolate (26+/-5 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.

Differential effects of isoflavones on bone formation in growing male and female mice

Few studies have examined the effects of isoflavones on bone formation during growth period in male and female animals. In this study, the effects of daidzein or genistein on bone formation were assessed in immature male and female mice. Five-week-old male and female mice were divided respectively into 3 groups (n=8 per group) as follows: control group (C) fed a control diet (AIN-93G), daidzein group (D) fed a control diet containing 0.08% pure daidzein, and genistein group (G) fed a control diet containing 0.08% pure genistein. After 4 weeks, the male D group had a significantly higher bone mineral density (BMD) in whole body, lumbar spine, and femur than did the C group. On the contrary, BMD of the whole body and femur in the female D group was significantly lower than that in the C group. The BMD of the whole femur in the male G group also was significantly higher than for the C group. Histologic analysis revealed that the bone formation rate was significantly higher in the male D and G groups, and lower in the female D group compared with the C group. These results suggest that daidzein has a specific, sexually dimorphic effect on bone formation and BMD during growth period in mice.

Monoclonal Antibody-Based Time-Resolved Fluorescence Immunoassays for Daidzein, Genistein, and Equol in Blood and Urine: Application to the Isoheart Intervention Study

Background: Time-resolved fluorescence immunoassays (TR-FIAs) for phytoestrogens in biological samples are an alternative to mass spectrometric methods. These immunoassays were used to test urine and plasma samples from individuals in a dietary intervention trial aimed at determining the efficacy of dietary isoflavones in reducing the risk of coronary heart disease in postmenopausal women.

Methods: We established murine monoclonal TR-FIA methods for daidzein, genistein, and equol. These assays could be performed manually or adapted to an automated analyzer for high throughput and increased accuracy. Analysis of urine was conducted on nonextracted samples. Blood analysis was performed on nonextracted samples for daidzein, whereas genistein and equol required diethyl-ether extraction.

Results: Comparison of monoclonal TR-FIA, commercial polyclonal antibody–based TR-FIA, and gas chromatography–mass spectrometry showed correlations (r, 0.911–0.994) across the concentration range observed in the Isoheart study (50 mg/day isoflavones). The concentrations of urinary daidzein and genistein observed during intervention demonstrated good compliance, and a corresponding increase in serum daidzein and genistein confirmed bioavailability of the isoflavone-rich foods; 33 of the 117 volunteers (28.2%) were classified as equol producers on the basis of their urinary equol concentration (&gt;936 nmol/L), and significant differences in the numbers of equol producers were observed between Berlin and the 3 other European cohorts studied.

Conclusions: The validated monoclonal TR-FIA methods are applicable for use in large-scale human phytoestrogen intervention studies and can be used to monitor compliance, demonstrate bioavailability, and assess equol producer status.

High throughput quantification of phytoestrogens in human urine and serum using liquid chromatography/tandem mass spectrometry (LC-MS/MS)

Phytoestrogens are currently the subject of intense study owing to their potential protective effects against a number of complex diseases. However, in order to investigate the interactions between phytoestrogens and disease state effectively, it is necessary to have analytical methods which are sensitive, reproducible, and require low sample volumes. We report an assay for three isoflavones (daidzein, genistein, and glycitein), two metabolites of daidzein (equol and O-desmethylangolensin), three lignans (secoisolariciresinol, enterodiol, and enterolactone), and one flavanone (naringenin) in human urine and serum. A high throughput of samples has been achieved via the use of 96-well plate sample extraction and liquid chromatography/tandem mass spectrometry (LC-MS/MS) analysis incorporating column switching, thus making the assay suitable for use on large sample numbers, such as those found in epidemiological studies. The robustness of the assay was proven via the comparison of data generated on two different LC-MS/MS systems, with and without column switching.

Isolated isoflavones do not affect the circulating insulin-like growth factor system in men at increased colorectal cancer risk

Epidemiological studies show that increased insulin-like growth factor (IGF)-I concentrations are related to increased colorectal cancer risk. A reduced colorectal cancer risk has been associated with isoflavones, which might affect the IGF-system because of their weak estrogenic activity. We conducted a randomized, placebo-controlled, double-blind crossover study to investigate the effect of an 8-wk isolated isoflavone supplementation (84 mg/d) on serum concentrations of total IGF-I, free IGF-I, total IGF-II, IGF binding protein (BP)-1, IGFBP-2, and IGFBP-3. Additionally, we investigated whether IGF-system component differences were related to concentrations of the more potent estrogenic isoflavone metabolite, equol. Our study population consisted of 37 men with a family history of colorectal cancer or a personal history of colorectal adenomas. Isoflavone supplementation did not significantly affect serum total IGF-I concentrations (relative difference between serum total IGF-I concentrations after isoflavone supplementation and after placebo: -1.3%, 95% CI -8.6 to 6.0%). Neither free IGF-I, nor total IGF-II, IGFBP-1, IGFBP-2, or IGFBP-3 concentrations were significantly altered. Interestingly, the change in serum IGF-I concentrations after isoflavone supplementation was negatively associated with serum equol concentrations (r=-0.49, P=0.002). In conclusion, isolated isoflavones did not affect the circulating IGF-system in a male high-risk population for colorectal cancer. However, to our knowledge, this is the first study that suggests isoflavones might have an IGF-I lowering effect in equol producers only. This underlines the importance of taking into account equol status in future isoflavone intervention studies.

Liquid chromatography–mass spectrometric analysis of puerarin and its metabolite in human urine

A specific LC-MS method was developed that allowed simultaneous determination of puerarin (PU) and its major metabolite, daidzein (DA), in human urine samples. PU and DA were separated on a packed capillary ODS column with on column concentration. Identification and quantification of the analytes were performed with ESI-Q-TOF mass spectroscopy in negative ionization mode. The method was validated, yielding calibration curves with correlation coefficients greater than 0.998. The LOQ for PU and DA from human urine samples was 0.1 and 0.05 nmol/mL, respectively. Assay accuracy and precision of quality control samples were within +/- 15%. Recoveries of PU and DA in spiked samples were in the range of 79.6-90.4 and 82.3-92.4%, respectively.

Application of coulometric electrode array detection to the analysis of isoflavonoids and lignans

A comprehensive review of the available methods for the analysis of isoflavonoids and lignans in biological matrices based on coulometric electrode array detection (CEAD) is presented. Different aspects such as sample extraction and purification procedures as well as instrumental settings and method validation are discussed. Comparisons with other available protocols using different detection techniques such as mass spectrometry or immunoassay are also reported to underline the versatility and reliability of the detector. Practical notes and tips for scientists working with CEAD are also provided.

X-Ray Single-Crystal Analysis of (−)-(S)-Equol Isolated from Rat's Feces

The biological effects of soy isoflavones have attracted considerable interest in recent years, leading to numerous studies on dietary intake and epidemiology. (-)-(S)-equol (3) is a metabolite produced in vivo from the isoflavone daidzein, a kind of soy phytoestrogen, by the action of gut microflora. It has higher biological activity than its precursor. Here, we wish to report the isolation and first X-ray crystal structure of 3 from the feces of rats fed a soy-isoflavone-containing diet.

Progress in Lanthanides as Luminescent Probes

Lanthanides have recently found applications in different fields of biomolecular and medical research. Luminescent lanthanide chelates have created interest mainly due to their unique luminescent properties, such as their long Stokes' shift and exceptional decay times allowing efficient temporal discrimination of background interferences in the assays, such as immunoassays. Recently, new organometallic complexes have been developed giving opportunities to novel applications, in heterogeneous and homogeneous immunoassays, DNA hybridization assays, high-throughput screening as well as in imaging. In addition, encapsulating the chelates into suitable matrix in beads enables the use of new members of lanthanides extending the emission wavelength to micrometer range and decays from a few microseconds to milliseconds. As the luminescence is derived from complicated intra-chelate energy transfer, it also gives novel opportunities to exploit these levels in different types of energy transfer based applications. This review gives a short overview of recent development of lanthanide chelate-labels and discusses in more details of energy levels and their exploitation in new assay formats.

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

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=0.02), SHBG and BMI (P=0.01), DHEA-S and dietary fiber (P=0.04), and A and protein:carbohydrate ratio (P=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=0.14) and SHBG (P=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.

Randomized controlled trial of the effects of soy protein containing isoflavones on vascular function in postmenopausal women

BACKGROUND

The incidence of cardiovascular disease increases after menopause, possibly because of the decline in estrogen. Soy protein, a rich source of estrogen-like isoflavones, is hypothesized to improve vascular function.

OBJECTIVE

The objective of this study was to investigate whether supplementation with soy protein, a rich source of estrogen-like isoflavones, improves vascular function.

DESIGN

We performed a 12-mo double-blind randomized trial to compare the effects of soy protein containing 99 mg isoflavones/d (aglycone weights) with those of milk protein (placebo) on blood pressure and endothelial function in 202 postmenopausal women aged 60-75 y.

RESULTS

Changes in endothelial function during the intervention were not significantly different between the soy and the placebo groups. After the intervention, systolic blood pressure increased in the soy group significantly more than it did in the placebo group; the difference in change was 4.3 mm Hg (95% CI: 0.3, 8.4 mm Hg; P = 0.04) for systolic blood pressure, but only 2.0 mm Hg (95% CI: -0.74, 4.71 mm Hg; P = 0.15) for diastolic blood pressure. In the soy group only, systolic and diastolic blood pressure decreased and endothelial function improved in the equol producers, whereas systolic and diastolic blood pressure increased and endothelial function deteriorated in the equol nonproducers.

CONCLUSIONS

The results of this trial do not support the hypothesis that soy protein containing isoflavones have beneficial effects on vascular function in older postmenopausal women. Whether certain subgroups of women (eg, equol producers) do benefit from the intervention remains to be elucidated.

Probiotic consumption does not enhance the cholesterol-lowering effect of soy in postmenopausal women

Numerous studies report that soy lowers cholesterol. Probiotic bacteria were also reported to lower total cholesterol (TC) and LDL cholesterol (LDL-C). We hypothesized that by altering intestinal microflora, probiotic consumption may also change phytoestrogen metabolism and enhance the effects of soy. To evaluate the independent and interactive effects of probiotic bacteria and soy on plasma TC, LDL-C, HDL cholesterol (HDL-C), and triglycerides (TG), 37 women with a baseline TC of 5.24 mmol/L were given the following 4 treatments for 6 wk each in a randomized crossover design: soy protein isolate (26 +/- 5 g soy protein containing 44 +/- 8 mg isoflavones/d); soy protein isolate + probiotic capsules (10(9) colony-forming units Lactobacillus acidophilus DDS-1 and Bifidobacterium longum); milk protein isolate (26 +/- 5 g milk protein/d); and milk protein isolate + probiotic. Soy consumption decreased plasma TC by 2.2% (P = 0.02) and LDL-C by 3.5% (P = 0.005), increased HDL-C by 4.2% (P = 0.006) and tended to decrease TG (P = 0.07) compared with milk protein intake. When divided according to initial TC concentration, soy effects were observed only in hypercholesterolemic women (TC > 5.17 mmol/L). In this subgroup, soy treatments decreased plasma TC by 3.3% (P = 0.01), LDL-C by 4.5% (P = 0.004), and TG by 10.6% (P = 0.02), and increased HDL-C by 4.2% (P = 0.02). When subjects were divided on the basis of plasma and urine concentrations of the isoflavone metabolite, equol, equol producers and nonproducers did not differ in baseline lipids or in the effects of soy. Probiotics did not lower cholesterol or enhance the effects of soy. These results confirm a beneficial effect of soy on plasma cholesterol in mildly hypercholesterolemic postmenopausal women independent of equol production status, but do not support an independent or additive effect of these particular probiotic bacteria.

Equol, a metabolite of daidzein, inhibits bone loss in ovariectomized mice

Soybean isoflavones have structures similar to that of estrogen and have received attention as alternatives to hormone replacement therapy for the prevention of postmenopausal osteoporosis. Daidzein, a major isoflavone found in soybean, is metabolized to equol by gut microflora, and the metabolite exhibits a stronger estrogenic activity than daidzein. However, there is no direct evidence that equol affects bone metabolism. In this study, we examined the effect of equol on the inhibition of bone loss in ovariectomized (OVX) mice. Female mice (8 wk old) were assigned to 5 groups as follows: sham-operated (sham), OVX, OVX + 0.1 mg/d equol administration (0.1 Eq), OVX + 0.5 mg/d equol administration (0.5 Eq), and OVX + 0.03 microg/d 17beta-estradiol administration (E(2)). Equol and E(2) were administered s.c., using a mini-osmotic pump. At 4 wk after the intervention, uterine weight was less in the OVX mice than in sham-operated mice (P < 0.05). The weight was maintained in the E(2) group. In contrast, administration of equol at doses used in this study did not affect uterine atrophy in OVX mice. Bone mineral density (BMD) for the whole body in the OVX group measured by dual-energy X-ray absorptiometry was lower than that in the sham group, whereas administration of 0.5 mg/d Eq as well as E(2) maintained the BMD. The BMD of the femur and lumbar spine in the OVX group was also lower than those in the sham group, and treatment with 0.5 mg/d Eq maintained it. Notably, the BMD of the proximal femur in the 0.5 Eq group was the same as that of the sham group. E(2) inhibited bone loss from all regions induced by OVX. These results suggest that equol, a major metabolite of daidzein, inhibits bone loss apparently without estrogenic activity in the reproductive organs of OVX mice.

Plasma phytoestrogens are not altered by probiotic consumption in postmenopausal women with and without a history of breast cancer

Soy phytoestrogens were suggested to reduce the risk of a number of diseases including breast cancer. Given that these compounds are metabolized by bacteria, alteration of intestinal bacteria and enzymes may affect phytoestrogen metabolism. We hypothesized that probiotics, when consumed with soy protein, would increase plasma isoflavones, as well as equol producer frequency, in postmenopausal women. We further hypothesized that these effects would differ between women who have had breast cancer and women who have not. To test these hypotheses, 20 breast cancer survivors and 20 controls completed four 6-wk treatments in a randomized, crossover design: supplementation with soy protein (S) (26.6 +/- 4.5 g protein, 44.4 +/- 7.5 mg isoflavones/d); soy + probiotics (S+P) (10(9) colony-forming units Lactobacillus acidophilus DDS+1 and Bifidobacterium longum, 15-30 mg fructooligosaccharide/d); milk protein (M) (26.6 +/- 4.5 g protein/d); and milk + probiotics (M+P). Plasma phytoestrogen concentrations did not differ between controls and survivors, although genistein tended to be lower in survivors at baseline (P = 0.15), and during soy (P = 0.16) and milk protein (P = 0.16) consumption. As expected, soy consumption increased plasma phytoestrogen concentrations (P < 0.0001). Plasma phytoestrogen concentrations and the number of equol producers did not differ between the S and S+P diets. At the same time, plasma equol concentrations as well as urinary equol excretion in 2 subjects were more than 7-fold different between the 2 diets. These results indicate that this particular probiotic supplement does not generally affect plasma isoflavones, although the large differences between plasma and urinary equol in some subjects suggest that equol producer status may be modifiable in some individuals.

Visual spatial memory is enhanced in female rats (but inhibited in males) by dietary soy phytoestrogens

BACKGROUND

In learning and memory tasks, requiring visual spatial memory (VSM), males exhibit superior performance to females (a difference attributed to the hormonal influence of estrogen). This study examined the influence of phytoestrogens (estrogen-like plant compounds) on VSM, utilizing radial arm-maze methods to examine varying aspects of memory. Additionally, brain phytoestrogen, calbindin (CALB), and cyclooxygenase-2 (COX-2) levels were determined.

RESULTS

Female rats receiving lifelong exposure to a high-phytoestrogen containing diet (Phyto-600) acquired the maze faster than females fed a phytoestrogen-free diet (Phyto-free); in males the opposite diet effect was identified. In a separate experiment, at 80 days-of-age, animals fed the Phyto-600 diet lifelong either remained on the Phyto-600 or were changed to the Phyto-free diet until 120 days-of-age. Following the diet change Phyto-600 females outperformed females switched to the Phyto-free diet, while in males the opposite diet effect was identified.Furthermore, males fed the Phyto-600 diet had significantly higher phytoestrogen concentrations in a number of brain regions (frontal cortex, amygdala & cerebellum); in frontal cortex, expression of CALB (a neuroprotective calcium-binding protein) decreased while COX-2 (an inducible inflammatory factor prevalent in Alzheimer's disease) increased.

CONCLUSIONS

Results suggest that dietary phytoestrogens significantly sex-reversed the normal sexually dimorphic expression of VSM. Specifically, in tasks requiring the use of reference, but not working, memory, VSM was enhanced in females fed the Phyto-600 diet, whereas, in males VSM was inhibited by the same diet. These findings suggest that dietary soy derived phytoestrogens can influence learning and memory and alter the expression of proteins involved in neural protection and inflammation in rats.