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PubMed2004

Urinary isoflavone kinetics: the effect of age, gender, food matrix and chemical composition.

Urinary isoflavone excretion is used to monitor compliance and examine biological effects. The present study determined if there were alterations in urinary isoflavone excretion following the ingestion of different soya foods and if age and gender potentially modified profiles. Twenty premenopausal women, seventeen post-menopausal women and twenty men received a defined single oral bolus dose (0.44 mg isoflavones/kg body weight) of soya milk, textured vegetable protein (TVP) or tempeh on three separate occasions. Baseline and four consecutive complete 24 h pooled urines were collected during each period. Urinary genistein recovery was influenced by gender and food matrix. For women the urinary genistein recovery was higher following soya-milk consumption compared with TVP (P<0.05). Tempeh consumption also resulted in an increased urinary genistein recovery relative to soya milk in premenopausal women (P<0.052). No differences in urinary genistein recoveries between soya foods were observed in the men. Although urinary daidzein excretion was similar across the foods studied and was not affected by age or gender, conversion to its intestinal metabolite, equol, resulted in potential matrix and chemical composition effects; urinary equol excretion was higher (P<0.01) following tempeh ingestion among equol producers. Together these data suggest that the fractional absorption of genistein is potentially different in men and women and is influenced by the food matrix and chemical composition. Furthermore, the data suggest that the metabolism of daidzein may be altered by the chemical composition of the isoflavones ingested. Further studies are required to examine the effect of higher intake and define the relative influence of these factors in elderly population groups.

Adolescent↗
PubMed2004

Lactobacillus gasseri: effects on mouse intestinal flora enzyme activity and isoflavonoids in the caecum and plasma.

The effects of Lactobacillus gasseri JCM 1131(T) on isoflavonoid levels within the caecum and plasma were assessed in adult mice. Male 5-week-old mice were fed an AIN 93M diet for 30 d. Two groups of mice were administered either L. gasseri JCM 1131(T) (the LGI group) or physiological saline solution (the control (CI) group) daily for 5 d before dissection. The plasma daidzein concentration was significantly higher in the LGI group, however, their plasma equol concentration was significantly less than in the CI group. The total amount of equol present as aglycone in the caecum was significantly greater in the CI group, but there was no significant difference in the total daidzein present as caecal aglycone. In an in vitro incubation of daidzein with the faecal flora of mice, the equol concentration was significantly higher in the CI group. The numbers of lactobacilli present were significantly higher in the LGI group. The present data suggest that the administration of L. gasseri is likely to influence the effect of isoflavonoids on the host via changes in the gastrointestinal environment.

Animals↗
PubMed1984

Nonsteroidal estrogens of dietary origin: possible roles in hormone-dependent disease.

Equol, a nonsteroidal estrogen of dietary origin, was recently identified in human urine, and is excreted in amounts comparable to the classical steroidal estrogens. We confirm here that phytoestrogens which are abundant in dietary soya protein are converted by human gastrointestinal flora to this weak estrogen. After the ingestion of meals containing cooked soya protein the urinary excretion of equol in four of six subjects studied increased by up to 1000-fold and this compound was the major phenolic compound found in the urine. These data also indicate that some subjects are unable to either produce or excrete equol despite the challenge of a diet containing soya. In view of the increasing use of commercial soya products in the diet and the capacity of human bacterial flora to synthesize this weak estrogen from the abundance of phytoestrogens in soya, the potential relevance of these observations to the diseases implicating steroid hormones is discussed.

Adult↗
PubMed2003

Bioavailability of soybean isoflavones from aglycone and glucoside forms in American women.

BACKGROUND: Test results on the bioavailability of isoflavones in the aglycone or glucoside form in Eastern and Western human subjects are contradictory. OBJECTIVE: The objective was to investigate the bioavailability of the soy isoflavones daidzein and genistein in American women with typical American dietary habits after ingestion of the aglycone or glucoside form of isoflavones. DESIGN: Fifteen American women aged 46 +/- 6 y participated in a randomized, double-blind study. Blood samples were collected 0, 1, 2, 4, 8, 12, 24, and 48 h after consumption of aglycone or glucoside tablets with breakfast. The plasma curves for daidzein, genistein, and equol were constructed and the postprandial maximum concentration (C(max)), time to the maximum concentration (t(max)), and area under the curve (AUC) were determined. RESULTS: Isoflavone concentrations peaked early (1-2 h) in plasma and peaked again at 4-8 h. Mean C(max), t(max), and AUC values for genistein were not significantly different after ingestion of aglycone or glucoside. However, C(max) and AUC values, but not t(max), were significantly higher for daidzein after aglycone ingestion, which was partly due to its higher content in the aglycone tablets. Equol appeared after 4 h and remained elevated after 48 h. Despite a higher content of daidzein in the aglycone tablets, the AUC for equol was significantly higher after ingestion of the glucoside tablets, probably because of the metabolic action of intestinal bacteria during the long intestinal transit time of glucoside. CONCLUSION: The apparent bioavailability of genistein and daidzein is not different when consumed as either aglycone or glucoside by American women.

Adult↗
PubMed2002

Phytoestrogen concentrations in serum from Japanese men and women over forty years of age.

Asian individuals have much lower incidences of prostate and breast cancer than populations from Western developed countries. They also consume a lower fat, higher fiber diet, with a large intake of phytoestrogens. These phytoestrogens may protect against hormone-dependent cancers and other diseases. Our study used established gas chromatography-mass spectrometry (GC-MS) methodologies to measure the concentrations of four phytoestrogens (daidzein, genistein, equol and enterolactone) in serum samples obtained from Japanese men (n = 102) and women (n = 125) > 40 y old. The results were compared with those obtained with samples from the UK. The Japanese men and women had higher (P < 0.001) concentrations of circulating daidzein, genistein and equol than individuals from the UK. The mean concentration of genistein in Japanese men, for example, was 492.7 nmol/L, compared with 33.2 nmol/L in men from the UK. The two populations, however, had similar serum concentrations of enterolactone. Furthermore, 58% of the Japanese men and 38% of the Japanese women had equol concentrations > 20 nmol/L, compared with none of the UK men and 2.2% of the UK women. These results support previously published GC-MS results from studies with low numbers of samples.

4-Butyrolactone↗
PubMed2004

Distribution of soy-derived phytoestrogens in human breast tissue and biological fluids.

OBJECTIVE: Soy-derived phytoestrogens may exert several health-beneficial effects. Although plasma and urine levels of these compounds after ingestion have been thoroughly investigated, little is known about their tissue distribution, which is particularly important for tissues with high endogenous estrogen and estrogen receptor concentrations. We aimed to investigate the concentrations of genistein, daidzein, and equol in human breast tissue homogenate and to compare these with the corresponding values in serum and urine. METHODS: A randomized, double-blind, placebo-controlled study was undertaken to evaluate the concentrations of soy-derived phytoestrogens achieved in breast tissue homogenate, serum, and urine after ingestion of either a soy-based food supplement (n = 9) or a placebo tablet (n = 19) for 5 consecutive evenings before aesthetic breast surgery. To account for the heterogeneity of the breast tissue samples, markers for cellularity, epithelial content, blood vessel content, and total fat were determined. RESULTS: Urine concentrations of genistein, daidzein, and equol were significantly higher in the soy-supplemented subjects than in the subjects ingesting the placebo (P <.05). Only genistein was found to be significantly higher in serum of the soy group than in the placebo group, and no significant differences were found in breast tissue homogenate concentrations of all analytes between the 2 groups. CONCLUSION: Intake of soy-based food supplements for 5 consecutive days did not result in significantly higher genistein, daidzein, and equol concentrations in breast tissue homogenate when compared with the placebo group. The concentrations were in the low nanomolar range, whereas in the corresponding serum samples, concentrations were a hundred-fold higher.

Adult↗
PubMed2005

Phytoestrogens and their metabolites inhibit the sensitivity of the bovine corpus luteum to luteotropic factors.

The aim of this study was to examine whether active metabolites of phytoestrogens (equol and para-ethyl-phenol) inhibit sensitivity of bovine corpus luteum (CL) to luteinizing hormone (LH) and to auto/paracrine luteotropic factors (prostaglandin E2-PGE2 and prostaglandin F(2alpha)-PGF(2alpha)), and whether they influence pulsatile progesterone (P4) secretion by the bovine CL. In in vivo experiments, high levels of equol and para-ethyl-phenol were found in plasma and in the CL tissue of heifers and cows fed a soy bean diet (2.5 kg/animal/day), along with lower concentrations of P4 (P < 0.05). Both Prostaglandins (PG) and LH strongly stimulated P4 secretion in cultured pieces of CL that were collected from cows fed a standard diet (P < 0.01). There was no effect of PGs and LH on P4 stimulation in CLs obtained from cows fed a diet rich in soy bean. Finally, we examined whether active metabolites of phytoestrogens participated in regulation of pulsatile P4 secretion and LH-stimulated P4 secretion in vitro using a microdialysis system. Equol and para-ethyl-phenol had no effect on basic and pulsatile P4 secretion in CLs during 240 min of perfusion when compared to the control (P < 0.05). However, they inhibited LH-stimulated P4 secretion (P < 0.05). Phytoestrogens and their metabolites may disrupt CL function by inhibiting PG- and LH-stimulated P4 secretion.

Adipose Tissue↗
PubMed1994

Determination of lignans and isoflavonoids in human female plasma following dietary supplementation.

Plasma levels of the lignans enterodiol and enterolactone, and also the isoflavonic phyto-oestrogens daidzein, equol and genistein, are reported for postmenopausal Australian women consuming a traditional diet supplemented with linseed, soya flour or clover sprouts. Analysis was performed by gas chromatography-mass spectrometry, after enzymatic hydrolysis and ion-exchange chromatography. Following linseed supplementation, combined levels of enterolactone and enterodiol reached 500 ng/ml, whereas after soya flour or clover sprouts the respective concentrations of equol, daidzein and genistein reached 43, 312 and 148 ng/ml. Not all subjects were able to produce equol from daidzein. The possible relationship and role of these weak dietary oestrogens as restraining factors in the development of hormone-dependent cancers in Asian populations is discussed.

4-Butyrolactone↗
PubMed2000

Comparison of isoflavones among dietary intake, plasma concentration and urinary excretion for accurate estimation of phytoestrogen intake.

Biological effects of dietary isoflavones, such as daidzein and genistein are of interest in preventive medicine. We estimated the dietary intake of isoflavones from dietary records and compared the values with the plasma concentrations and urinary excretions in Japanese middle-aged women. The dietary intake of daidzein and genistein was 64.6 and 111.6 mumol /day/capita (16.4 and 30.1 mg/day/capita), respectively. The isoflavones intake was mostly attributable to tofu, natto and miso. The median of plasma daidzein and genistein concentration was 72.46 and 206.09 nmol/L, respectively. The median of urinary excretion was 20.54 mumol /day for daidzein, 10.79 for genistein, 15.74 for equol and 1.64 for O-desmethylangolensin (O-DMA). Equol and O-DMA were excreted by 50% and 84% of all participants, respectively. Equol metabolizers were significantly lower the plasma and urinary daidzein and urinary O-DMA. The dietary intake of daidzein and genistein after the adjustment for total energy intake was significantly correlated with the urinary excretion (r = 0.365 for daidzein and r = 0.346 for genistein) and plasma concentration (r = 0.335 for daidzein and r = 0.429 for genistein). The plasma concentration of isoflavones was also significantly correlated with the urinary excretion. We conclude that in epidemiological studies measurements of plasma concentration or urinary excretion of these isoflavones are useful biomarkers of dietary intake and important for studies on their relation to human health.

Adult↗
PubMed2004

Isoflavones in several clover species and in milk from goats fed clovers.

Isoflavones that exist in forages such as clover can move in milk, and may have beneficial effects on human health. We measured the isoflavones in subterranean (cv Yarloop, Geraldton, Dinninup and Dwalganup) and red (cv Merviot and Hamua) clovers, grown in a mountain environment, and in the milk of two goats fed a fresh mixture of the four subterranean clovers gathered at flowering stage. Isoflavone glycosides were hydrolysed with an improved beta glycosidase method. Free aglycones (FA) and the hydrolysed glycosides + free aglycones fraction (HF) were analysed by HPLC. In milk, the methanol extracted compounds were deconjugated and similarly analysed. Total HF was highest in Yarloop (19 g kg(-1) dry matter) and was three times lower in Merviot. Formononetin was the major compound (46-64% of total HF). FA varied from 30 to 73% of HF. Milk contained formononetin (50 microg L(-1)), similar amounts of equol and p ethylphenol (about 250 microg L(-1)), and equol like compounds (1120 microg L(-1)). Equol, which has estrogenic activity, and p ethylphenol were produced by biotransformation of formononetin, and biochanin A or genistein, respectively. The modulation of isoflavone amounts in milk and the estimation of their interests for human health warrant further investigation.

Animal Feed↗
PubMed2005

Circulating levels of isoflavones and markers of 5alpha-reductase activity are higher in Japanese compared with New Zealand males: what is the role of circulating steroids in prostate disease?

Epidemiological evidence implicates dietary isoflavone intake as protective against prostate disease. A putative mechanism is attenuated circulating androgen levels in male populations consuming an isoflavone rich diet. We investigated this hypothesis by collecting plasma from 60 Japanese and 60 New Zealand males aged between 21 and 31 years each consuming their traditional diets. We measured plasma testosterone, dihydrotestosterone (DHT), androstenedione, dehydroepiandrosterone sulfate (DHEAS), the combined levels of androsterone sulfate and epiandrosterone sulfate (AoS/epiAoS), sex hormone-binding globulin, and cortisol and corticosteroid-binding globulin as well as the isoflavones genistein and equol. Plasma genistein and equol levels were several times higher in Japanese males as would be expected from an isoflavone rich diet. However, androstenedione, DHEAS, calculated free testosterone and paradoxically markers of 5alpha-reductase, DHT and AoS/epiAoS were all also significantly higher in Japanese rather than the New Zealand male counterparts. All other comparisons were not significant. Plasma DHT and DHEAS correlated positively with plasma equol and plasma AoS/epiAoS correlated positively with genistein levels. Taken together the results suggest that, rather than reduced levels of steroidogenesis, Japanese males may have increased 5alpha-reductase activity and possibly altered 17beta OH steroid dehydrogenase activity. Significantly the positive association between isoflavones levels and 5alpha-steroids is counter-intuitive to isoflavone intake offering prostate protection, unless this is postulated to occur through other mechanisms.

Adult↗
PubMed2005

Short-term soy and probiotic supplementation does not markedly affect concentrations of reproductive hormones in postmenopausal women with and without histories of breast cancer.

BACKGROUND: Observational studies suggest that dietary isoflavones reduce breast cancer risk, and this may be caused in part by effects on endogenous hormone concentrations. Because intestinal bacteria metabolize isoflavones, it was hypothesized that consumption of probiotic bacteria would enhance the biologic effects of isoflavones, including effects on endogenous hormones. DESIGN: Twenty (20) postmenopausal breast cancer survivors and 20 healthy postmenopausal women completed four 42-day diet periods in a randomized, crossover design. They received one of the following: isolated soy protein; isolated milk protein; soy + probiotic capsules; or milk + probiotic capsules. Each protein supplement provided 0.38 g protein/(kg body weight/day) (26.6 +/- 4.5 g protein/day) and soy protein provided 0.64 mg isoflavones/(kg body weight/day) (44.4 +/- 7.5 mg isoflavones/day). Probiotic capsules provided 10(9) colony-forming units Lactobacillus acidophilus (strain DDS-1), Bifidobacterium longum, and 15-20 mg fructo-oligosaccharide. MEASURES: Plasma samples were collected at baseline and after each diet for analysis of estrogens, follicle-stimulating hormone (FSH), androgens, and sex hormone?binding globulin (SHBG). RESULTS: Hormone levels were not affected by soy, probiotic supplements, or equol producer status, and neither cancer status nor equol producer status altered the effects of soy or probiotics. Furthermore probiotics did not alter the effects of soy consumption. Soy protein tended to decrease SHBG compared to milk protein diets (p = 0.05), although both proteins significantly decreased SHBG relative to baseline (p = 0.0001 and p = 0.03). CONCLUSIONS: These data suggest that short-term, moderate consumption of isoflavone-containing soy protein and consumption of these particular probiotic capsules do not significantly alter reproductive hormone concentrations in breast cancer survivors or controls, regardless of equol producer status.

Administration, Oral↗
PubMed2005

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.

Aged↗
PubMed2006

Soy isoflavonoid effects on endogenous estrogen metabolism in postmenopausal female monkeys.

Endogenous estrogens are important determinants of breast cancer risk in postmenopausal women. In this study we evaluated the effects of dietary soy isoflavonoids on endogenous estrogen metabolism in a postmenopausal primate model. Ovariectomized female cynomolgus monkeys were randomized to receive one of three diets for 36 months: (i) isoflavonoid-depleted soy protein isolate (SPI-) (n = 29); (ii) soy protein isolate with 129 mg isoflavonoids/1800 kcal diet (8.6 mg isoflavonoids/kg body weight (BW), expressed in aglycone units) (SPI+) (n = 29) or (iii) isoflavonoid-depleted soy protein isolate with conjugated equine estrogens (CEE) at a dose of 0.625 mg/1800 kcal diet (0.042 mg CEE/kg BW) (n = 30). Mean plasma isoflavonoid concentrations in the SPI+ group were 946.9 +/- 135.9 nmol/l, and equol was the primary circulating isoflavonoid (549.7 +/- 61.6 nmol/l). The SPI+ diet resulted in lower serum estrone (E(1)) after 29 (-26%, P = 0.03) and 34 months (-21%, P = 0.04) compared to the SPI- diet, while urinary 2-hydroxyestrone (P = 0.005) and the 2 to 16alpha-hydroxyestrone ratio (P < 0.0001) were markedly higher in the SPI+ group compared to SPI-. Isoflavonoid treatment did not significantly alter gene markers of estrogen metabolism or estrogen receptor agonist activity in breast tissue. Within the SPI+ group, higher concentrations of serum equol (but not daidzein or genistein) corresponded to significantly lower serum E(1), mammary gland epithelial area and uterine weight (P < 0.01 for all). These findings suggest that long-term exposure to soy isoflavonoids, equol in particular, may facilitate endogenous estrogen clearance and catabolism to more benign 2-hydroxylated metabolites.

Animals↗
PubMed1998

Pharmacokinetics of soybean isoflavones in plasma, urine and feces of men after ingestion of 60 g baked soybean powder (kinako).

To take advantage of the various pharmacologic activities of soy bean isoflavones, more detailed studies of the absorption and excretion rates of these compounds in humans and subsequent evaluation of their bioavailabilities are required. We conducted a pharmacokinetic study of soybean isoflavones in seven healthy male volunteers. After ingestion of 60 g of kinako (baked soybean powder, containing 103 micromol daidzein and 112 micromol genistein), changes of the isoflavone and metabolite concentrations in plasma, urine and feces were measured by gas chromatography-mass spectrometry. The plasma concentration of genistein increased after 2 h and reached its highest value of 2.44 +/- 0.65 micromol/L 6 h later. The plasma concentration of daidzein peaked at 1.56 +/- 0.34 micromol/L at the same time, but it was always lower than that of genistein. Peak plasma concentration of O-desmethylangolensin (O-DMA) and equol appeared after the daidzein peak in four and two subjects, respectively. In contrast with plasma, daidzein was the main component in urine. Urinary daidzein excretion started to increase shortly after the rise in its plasma concentration and reached 2.4 micromol/h 8 h after ingestion of kinako. Genistein excretion in urine paralleled that of daidzein, but the value at 6 h was about half (1.1 micromol/h). The majority of ingested isoflavones after ingestion of kinako were recovered on d 2 or 3 in the feces. Total recovery of daidzein, O-DMA and equol from urine and feces was 54.7%, calculated from daidzein intake; 20.1% of administered genistein was recovered as genistein. The half-lives of plasma genistein and daidzein were 8.36 and 5.79 h, respectively. The individual plasma and urinary concentrations of equol and O-DMA were quite variable; subjects were classified as high and low metabolizers. The high plasma concentration of isoflavones for at least several hours after a single ingestion of soy protein suggests that these compounds may interact with macromolecules and have biological effects.

Absorption↗
PubMed2004

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.

Cross-Over Studies↗
PubMed2004

Serum phytoestrogens and prostate cancer risk in a nested case-control study among Japanese men.

The purpose of this study was to examine whether a high serum concentration of phytoestrogens reduces the risk of prostate cancer in a case-control study nested in a community-based cohort in Japan (Japan Collaborative Cohort (JACC) Study). Information on lifestyles and sera of the subjects were collected in 1988-90, and they were followed up to 1999. Incident and dead cases of prostate cancer and controls were matched for study area and age. Phytoestrogens and sex hormones in sera stored at - 80 degrees C were measured in 2002. Of 14,105 male subjects of the cohort who donated their sera, 52 cases and 151 controls were identified. Three datasets were analyzed; 1) all subjects, 2) 40 cases and 101 controls after excluding subjects with low testosterone levels who were suspected of having had medical intervention, and 3) 28 cases and 69 controls with prostate specific antigen level of </= 10.0 ng/ml. The odds ratio (OR) for the highest level to the lowest was 0.38 (95% confidence interval (CI); 0.13, 1.13) for genistein, 0.41 (0.15, 1.11) for daidzein, and 0.34 (0.11, 1.10) for equol for the second dataset. Genistein and daidzein showed similar findings in the third one. Equol and equol/daidzein ratio showed consistent findings in all three datasets (OR = 0.39, 95% CI; 0.13, 0.89, trend P = 0.02 for the first dataset). Their effects seemed to be independent of serum sex hormones. In conclusion, serum genistein, daidzein, and equol seemed to dose-dependently reduce prostate cancer risk.

Adult↗
PubMed1977

Radioactive conversion products of intramuscularly injected [4-14C]formononetin including sulfates in the urine of hens.

The phytoestrogen formononetin was injected intramuscularly as [4-14C]formononetin into two adult hens. Radioactive materials in the urine for the succeeding 14 days (hen 1) or 16 days (hen 2) were fractionated on DEAE-Sephadex-25 columns by elution with a gradient of NaCl; the four major fractions thus separated were examined by solvent partition, thin-layer chromatography, and enzymic cleavage. The following seven radioactive components were identified in the urine, the average proportions of each being given in terms of percentage of total 14C recovered from the urine: [14C]formononetin (4.3%); [14C]diaidzein (11.4%); [14C]equol (6.8%); [14C]daidzein monosulfate (30.4%); [14C]equol monosulfate (5.8%); [14C]diadzein disulfate (19.8%); and [14C]equol disulfate (6.5%). Small proportions of sulfates of unidentified radioactive phenols were present. Tests for presence of glucosiduronates of 14C-labelled material gave negative results. Radioactive formononetin sulfate was not detected in the urine of either hen.

Animals↗