Urinary Phytoestrogen Levels Are Associated with Female Hormonal Cancers: An Analysis of NHANES Data From 1999 to 2010.

Phytoestrogens are plant-derived compounds that are structurally similar to endogenous estrogens. Studies have shown phytoestrogens to have possible health benefits although they could also act as endocrine disruptors. This is particularly relevant for estrogen-dependent cancers since estrogens increase risk of breast, endometrial, and ovarian cancer. Using data from the National Health and Nutritional Examination Survey (NHANES), we assessed the associations between urinary phytoestrogens (daidzein, equol, o-Desmethylangolensin (O-DMA), genistein, enterodiol, enterolactone) and breast, endometrial, and ovarian cancer using multivariate logistic regression with odds ratios (ORs) and 95% confidence intervals (CIs). Cancer diagnosis and other characteristics were collected via in-person questionnaires. We found women in the highest tertile for daidzein and enterodiol had over twice the odds of having breast cancer (OR = 2.51, 95% CI 1.44-4.36 for daidzein, OR = 2.78, 95% CI 1.44-5.37 for enterodiol). In addition, women in the highest tertiles for daidzein and genistein had three to four times the odds of having endometrial cancer, respectively (OR = 3.09, 95% CI 1.01-9.49 for daidzein, OR = 4.00, 95% CI 1.38-11.59 for genistein). Overall, phytoestrogens were positively associated with breast and endometrial cancer although the associations varied by phytoestrogen type. Additional studies are needed to further inform phytoestrogens' role in disease etiology.Supplemental data for this article is available online at at https://doi.org/10.1080/01635581.2021.2020304.

Grading of Japanese Diet Intakes by 24-Hour Urine Analysis of Taurine and Soy Isoflavones in Relation to Cardiovascular Risks.

To investigate the association of the Japanese diet with risks for lifestyle-related diseases, the biomarkers of seafood and soybean consumption, taurine (T) and soy isoflavones (I), and others were analyzed in 24-hour urine (24U) samples collected from participants of the Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study coordinated by the World Health Organization (WHO). The data of T and I normalized for creatinine content in 24U were divided into five quintiles, T1 to T5, and I1 to I5. The total data of the collected samples were divided into 25 groups, which were obtained by 5 (T1-T5) × 5 (I1-I5) according to 24U excretions of T and I corresponding to the intake of seafood and soybeans from the least to the highest, respectively. Since these two nutrients were often consumed together in the Japanese diet, this characteristic was expressed as J1 to J5 based on the amounts of 24U T and I excretions. The risks for lifestyle-related diseases, obesity (body mass index, BMI), and cholesterolemia became lower during the transition from J1 to J5, while HDL cholesterol levels became higher from J1 to J5. On the contrary, urinary salt excretion and the sodium (Na)/potassium (K) ratio became higher from J1 to J5. Systolic blood measure was significantly lower in J3 than in J5. Diastolic blood pressure was also significantly lower in J3 than in J1. In conclusion, the higher the J score, which corresponds to Japanese dietary habits, the lower the BMI and cholesterol levels, as well as mortality rate from coronary heart disease, but the higher the average life expectancy among the Japanese. However, these higher J scorings were associated with high-salt intake and high Na/K ratios; therefore, they contributed to high blood pressure and high mortality rate caused by stroke in Japan. These results indicate that low-salt intake should be recommended to the Japanese who are consuming seafood and soy regularly in order to maintain lower blood pressure and to extend healthy life expectancy with a lower risk of stroke. Moreover, high scorings of the Japanese diet correspond to the high intake of magnesium (Mg) which is rich in seafood including seaweeds and soy. Therefore, low-salt seafood and soy intake is expected to reduce the incidence of the metabolic syndrome, the risk of which is inversely related to T and Mg intake.

The Connection between Urinary Equol Levels and the Prevalence of Atopic Dermatitis.

BACKGROUND: Soy isoflavones and their metabolites such as equol have been associated with a reduced risk of hormone-sensitive tumors and metabolic syndromes. However, individual soy isoflavones and equol levels in atopic dermatitis remain uninvestigated. OBJECTIVE: The aim of this study is to compare the levels of urinary daidzein, genistein, and equol between atopic dermatitis patients and normal subjects and to examine the correlation between equol concentration and the severity of clinical symptoms. METHODS: A cross-sectional study was conducted at Akita University Hospital and Aso Iizuka Hospital in Japan. Fifty patients with confirmed atopic dermatitis diagnosis and 67 healthy controls were recruited. Daidzein, genistein, and equol in urine were measured by using a high-performance liquid chromatography-mass spectrometry system. RESULTS: Urinary equol levels were significantly lower in the atopic dermatitis patients than in the healthy controls (p = 0.002). The difference was particularly noticeable in young people (6-19 years, p < 0.001). No correlations were found between urinary equol levels and the severity of clinical symptoms and laboratory data in the atopic dermatitis patients. CONCLUSION: Equol levels in childhood might be involved in the development of atopic dermatitis.

Urinary Isoflavones Levels in Relation to Serum Thyroid Hormone Concentrations in Female and Male Adults in the U.S. General Population.

Isoflavones are phytoestrogens found in plant-based foods and nutritional supplements. Experimental studies show a positive association between isoflavones and hypothyroidism, but epidemiological findings are conflicting. We used multivariable linear regression to examine the association between urinary isoflavone concentrations and serum thyroid hormone concentrations in the National Health and Nutrition Examination Survey (2007-2010). In this study, we found that Daidzein and O-DMA associations with free T4 were stronger among women: a 10-fold increase in daidzein was associated with a 3.2% (95% CI: 1.9%, 4.5%) increase in women and a 0.6% (95% CI: -1.7%, 0.6%) decrease in men and a 10-fold increase in O-DMA was related to a 2.0% (95% CI: 1.1%, 2.9%) increase in women and a 0.3% (95% CI: -1.2%, 0.5%) decrease in men. In this study, selected urinary isoflavone concentrations were associated with serum thyroid hormone concentration in a sex-dependent fashion.

Reduction of inflammation in chronic pancreatitis using a soy bread intervention: A feasibility study.

INTRODUCTION: Chronic pancreatitis is a chronic inflammatory disease, which progresses to fibrosis. Currently there are no interventions to delay or stop the progression to irreversible organ damage. In this study, we assessed the tolerability and feasibility of administering soy bread to reduce circulating inflammatory mediators. METHODS: Subjects with chronic pancreatitis diagnosed using the American Pancreatic Association diagnostic guidelines were enrolled. During the dose escalation (DE) phase, subjects received one week of soy bread based using a 3 + 3 dose-escalation design, which was then followed by a maximally tolerated dose (MTD) phase with four weeks of intervention. Dose-limiting toxicities (DLTs) were monitored. Plasma cytokine levels were measured using a Meso Scale Discovery multiplex assay kit. Isoflavonoid excretion in 24-h urine collection was used to measure soy bread compliance. RESULTS: Nine subjects completed the DE phase, and one subject completed the MTD phase without any DLTs at a maximum dosage of three slices (99 mg of isoflavones) per day. Reported compliance to soy bread intervention was 98%, and this was confirmed with urinary isoflavones and their metabolites detected in all subjects. There was a significant decline in the TNF-α level during the DE phase (2.667 vs 2.382 pg/mL, p = 0.039); other levels were similar. CONCLUSIONS: In this feasibility study, there was excellent compliance with a short-term intervention using soy bread in chronic pancreatitis. Reduction was seen in at least one pro-inflammatory cytokine with short-term intervention. Larger cohorts and longer interventions with soy are warranted to assess the efficacy of reducing pro-inflammatory mediators of disease.

Urinary equol, but not daidzein and genistein, was inversely associated with the risk of type 2 diabetes in Chinese adults.

PURPOSE: Many studies have examined the association of isoflavone intake with type 2 diabetes (T2D), and produced inconsistent results. Few studies, however, explored the association using objective biomarkers (particular for daidzein metabolite-equol) of isoflavones. We aimed to explore the association of urinary equol, daidzein and genistein concentrations with T2D and examine the mediating roles of high-sensitivity C-reactive protein (hsCRP) and retinol binding protein 4 (RBP4). METHODS: This prospective study included 2818 subjects. Urinary concentrations of equol, daidzein and genistein were measured by high-performance liquid chromatography-tandem mass spectrometry. The associations between urinary isoflavones and T2D incidence were evaluated by cox proportional hazards model. RESULTS: After adjustment for covariates, urinary equol except daidzein and genistein was inversely associated with T2D incidence. In comparison with the first tertile, multivariable adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs) for T2D incidence in the second and third tertile of equol concentration were 0.52 (0.37, 0.73) and 0.72 (0.53, 0.97), respectively. In stratified analyses by sex, the HR (95% CI) of men in the second vs. first tertile of equol was 0.29 (0.14, 0.58). Equivalent estimation in women was 0.67 (0.45, 1.01). Neither women nor men in the third tertile showed significant difference of T2D incidence compared with the first tertile. In path analyses, there was no evidence of mediating effects of hsCRP and RBP4 on the "equol-T2D" relationship. CONCLUSIONS: Urinary equol was favorably associated with a decreased T2D incidence in Chinese adults. The equol-T2D relationship might not be mediated by hsCRP and RBP4. TRIAL REGISTRATION: This study has been registered at http://www.clinicaltrials.gov as NCT03179657.

An investigation on the metabolic pathways of synthetic isoflavones by gas chromatography coupled to high accuracy mass spectrometry.

RATIONALE: Isoflavones are a group of flavonoids that may be of interest in sport doping because they can be used by athletes in the recovery periods after the administration of anabolic steroids, with the aim of increasing the natural production of luteinizing hormone (LH) and, consequently, the biosynthesis of endogenous androgens. METHODS: The in vivo metabolism of methoxyisoflavone (5-methyl-7-methoxyisoflavone) and ipriflavone (7-isopropoxyisoflavone), respectively present in a dietary supplement and in a pharmaceutical preparation, was investigated. The study was carried out by the analysis of urinary samples collected from male Caucasian subjects before, during and after the oral administration of methoxyisoflavone or ipriflavone. After enzymatic hydrolysis and liquid-liquid extraction, all urinary samples were analyzed by gas chromatography/quadrupole time-of-flight (qTOF MS system/qTOF) electron ionization mass spectrometry (EI-MS). RESULTS: Eight metabolites of methoxyisoflavone and six metabolites of ipriflavone were isolated. The corresponding accurate mass spectra are specific for isoflavone structures and revealed also a retro-Diels-Alder fragmentation. CONCLUSIONS: When excreted in large amounts, the urinary metabolites of methoxyisoflavone and ipriflavone can be traced to potential confounding factors in doping analysis. As methoxyisoflavone and ipriflavone have been shown to inhibit the enzyme aromatase, thus interfering with the normal metabolic pathways of testosterone, the detection of their intake, by screening for the presence of their main metabolites in urine, might be helpful in routine doping control analysis.

Rapid Screening and Identification of Daidzein Metabolites in Rats Based on UHPLC-LTQ-Orbitrap Mass Spectrometry Coupled with Data-Mining Technologies.

Daidzein, the main bioactive soy isoflavone in Nature, has been found to possess many biological functions. It has been investigated in particular as a phytoestrogen owing to the similarity of its structure with that of the human hormone estrogen. Due to the lack of comprehensive studies on daidzein metabolism, further research is still required to clarify its in vivo metabolic fate and intermediate processes. In this study, an efficient strategy was established using UHPLC-LTQ-Orbitrap mass spectrometry to profile the metabolism of daidzein in rats. Meanwhile, multiple data-mining methods including high-resolution extracted ion chromatogram (HREIC), multiple mass defect filtering (MMDF), neutral loss fragment (NLF), and diagnostic product ion (DPI) were utilized to investigate daidzein metabolites from the HR-ESI-MS¹ to ESI-MSn stage in both positive and negative ion modes. Consequently, 59 metabolites, including prototype compounds, were positively or tentatively elucidated based on reference standards, accurate mass measurements, mass fragmentation behaviors, chromatographic retention times, and corresponding calculated ClogP values. As a result, dehydration, hydrogenation, methylation, dimethylation, glucuronidation, glucosylation, sulfonation, ring-cleavage, and their composite reactions were ascertained to interpret its in vivo biotransformation. Overall, our results not only revealed the potential pharmacodynamics forms of daidzein, but also aid in establishing a practical strategy for rapid screening and identifying metabolites of natural compounds.

Soy Food Intake and Biomarkers of Breast Cancer Risk: Possible Difference in Asian Women?

Soy foods may protect against breast cancer in Asian but not in Western populations. We examined if the levels of various markers of breast cancer risk and inflammation, as well as the effects of soy food consumption on these markers, differ between Asian and non-Asian premenopausal women in two soy intervention trials. One study randomized 220 women to a 2-yr intervention and the other one randomized 96 women in a crossover design to examine the effects of consumption of 2 daily soy servings on nipple aspirate fluid (NAF) volume; estrogens in serum, NAF, and urine; insulin-like growth factor-1 (IGF-1), IGF-binding protein 3, and inflammatory markers in serum; and mammographic densities. Mixed linear models were applied to assess ethnic differences in biomarkers and response to the soy diet. Serum C-reactive protein, serum leptin, NAF volume, and NAF estrone sulfate were lower, while urinary isoflavones were higher in Asian than in non-Asian women. A significant interaction (pinteraction = 0.05) between ethnicity and soy diet was observed for IGF-1 but not for other biomarkers. The current findings suggest possible ethnic differences in levels of biomarkers for breast cancer risk but little evidence that Asian women respond differently to soy foods than non-Asian women.

Relationship of equol production between children aged 5-7 years and their mothers.

PURPOSE: The factors responsible for the production of isoflavone metabolites have not yet been identified. We aimed to examine the relationships of equol production between mother and child in a birth cohort in Japan. METHODS: Subjects were a part of the participants in a longitudinal study on pregnant women and their offspring. When children were 5-7 years old, mothers and children were asked to reply to a questionnaire on lifestyles and a 3-day child's dietary record. Mothers and children were given a bar-shaped soy snack (Soyjoy®) daily on two consecutive days (soy challenge). The snack contained 14 mg of overall soy isoflavones as the sum of aglycones and the glucosides for mothers and 7.5 mg for children. On the morning of day 0 and 3, they were asked to mail their first-void urines. Urinary isoflavone metabolites of 159 mother-child pairs were measured by a high-performance liquid chromatography method. RESULTS: Equol producers were 35.5 % among mothers and 13.8 % among children. Equol producer status of a child was neither associated with dietary intake nor with urinary levels of daidzein and genistein. After multiple adjustments for potential confounders, the estimated relative risk of equol producer was 2.75 (95 % confidence interval 1.00, 7.52) among children whose mother was an equol producer, compared with children whose mother was a non-producer. CONCLUSION: Child's equol production was associated with the mother's equol producer status. The effects of maternal factors on child's equol production should be studied further.

Urine phyto-oestrogen metabolites are not significantly associated with risk of type 2 diabetes: the Singapore Chinese health study.

We evaluated the relationship between urine concentrations of phyto-oestrogens (isoflavones and lignans) and risk of incident type 2 diabetes in middle-aged and elderly Chinese residing in Singapore. Urine metabolites of isoflavones and lignans were assayed by HPLC among 564 diabetes cases and 564 matched controls in a case-control study nested within the Singapore Chinese Health Study cohort. Participants were free of diagnosed diabetes, CVD and cancer at morning urine collections during 1999-2004. Cases were participants who reported to have physician-diagnosed diabetes at follow-up visits during 2006-2010, whereas controls were randomly selected among those who remained free of diabetes and were matched to the index cases by age, sex, dialect group and date of urine collection. Conditional logistic regression models were used to calculate OR and 95 % CI with adjustment for potential confounders. The mean age of the participants at the time of urine collection was 59·8 years, and the average interval between urine collection and diabetes diagnosis was 4·0 years. The multivariate-adjusted OR for diabetes were 1·00 (reference), 0·76 (95 % CI 0·52, 1·11), 0·78 (95 % CI 0·53, 1·14) and 0·79 (95 % CI 0·54, 1·15) across quartiles of urine isoflavones (P for trend=0·54), and were 1·00 (reference), 0·87 (95 % CI 0·60, 1·27), 1·10 (95 % CI 0·77, 1·56) and 0·93 (95 % CI 0·63, 1·37) for lignans (P for trend=0·93). The results were similar in men and women, as well as for individual metabolites of isoflavones (genistein, daidzein, glycitin and equol) or lignans (enterodiol and enterolactone). The present study did not find a significant association between urine phyto-oestrogen metabolites and risk of type 2 diabetes in Chinese adults.

Urinary phytoestrogens and cancer, cardiovascular, and all-cause mortality in the continuous National Health and Nutrition Examination Survey.

PURPOSE: Experimental studies suggest that phytoestrogen intake alters cancer and cardiovascular risk. This study investigated the associations of urinary phytoestrogens with total cancer (n = 79), cardiovascular (n = 108), and all-cause (n = 290) mortality among 5179 participants in the continuous National Health and Nutrition Examination Survey (1999-2004). METHODS: Urinary phytoestrogens were measured using high-performance liquid chromatography with tandem mass spectrometric detection. Survival analysis was performed to evaluate hazard ratios (HRs) and 95 % confidence intervals (CIs) for each of the three outcomes in relation to urinary phytoestrogens. RESULTS: After adjustment for confounders, higher urinary concentrations of total enterolignans were associated with a reduced risk of death from cardiovascular disease (HR for tertile 3 vs. tertile 1 0.48; 95 % CI 0.24, 0.97), whereas higher urinary concentrations of total isoflavones (HR for tertile 3 vs. tertile 1 2.14; 95 % CI 1.03, 4.47) and daidzein (HR for tertile 3 vs. tertile 1 2.05; 95 % CI 1.02, 4.11) were associated with an increased risk. A reduction in all-cause mortality was observed for elevated urinary concentrations of total enterolignans (HR for tertile 3 vs. tertile 1 0.65; 95 % CI 0.43, 0.96) and enterolactone (HR for tertile 3 vs. tertile 1 0.65; 95 % CI 0.44, 0.97). CONCLUSIONS: Some urinary phytoestrogens were associated with cardiovascular and all-cause mortality in a representative sample of the US population. This is one of the first studies that used urinary phytoestrogens as biomarkers of their dietary intake to evaluate the effect of these bioactive compounds on the risk of death from cancer and cardiovascular disease.

Soy isoflavone metabolism in cats compared with other species: urinary metabolite concentrations and glucuronidation by liver microsomes.

1. Soybean is a common source of protein in many pet foods. Slow glucuronidation of soy-derived isoflavones in cats has been hypothesized to result in accumulation with adverse health consequences. Here, we evaluated species' differences in soy isoflavone glucuronidation using urine samples from cats and dogs fed a soy-based diet and liver microsomes from cats compared with microsomes from 12 other species. 2. Significant concentrations of conjugated (but not unconjugated) genistein, daidzein and glycitein, and the gut microbiome metabolites, dihydrogenistein and dihydrodaidzein, were found in cat and dog urine samples. Substantial amounts of conjugated equol were also found in cat urine but not in dog urine. 3. ß-Glucuronidase treatment showed that all these compounds were significantly glucuronidated in dog urine while only daidzein (11%) and glycitein (37%) showed any glucuronidation in cat urine suggesting that alternate metabolic pathways including sulfation predominate in cats. 4. Glucuronidation rates of genistein, daidzein and equol by cat livers were consistently ranked within the lowest 3 out of 13 species' livers evaluated. Ferret and mongoose livers were also ranked in the lowest four species. 5. Our results demonstrate that glucuronidation is a minor pathway for soy isoflavone metabolism in cats compared with most other species.

A combination of soy isoflavones and cello-oligosaccharides changes equol/O-desmethylangolensin production ratio and attenuates bone fragility in ovariectomized mice.

We examined the cooperative effects of isoflavones and cello-oligosaccharides on daidzein metabolism and bone fragility in ovariectomized mice. Cello-oligosaccharides increased urinary equol and decreased O-desmethylangolensin. A combination of isoflavones and cello-oligosaccharides attenuated decreases in bone breaking force and stiffness caused by ovariectomy. Combination treatment with isofalvones and cello-oligosaccharides increases urinary equol/O-desmethylangolensin production ratio and prevents ovariectomy-induced abnormalities in bone strength.

Effects of an equol-producing bacterium isolated from human faeces on isoflavone and lignan metabolism in mice.

BACKGROUND: Equol is a metabolite of daidzein that is produced by intestinal microbiota. The oestrogenic activity of equol is stronger than daidzein. Equol-producing bacteria are believed to play an important role in the gut. The rod-shaped and Gram-positive anaerobic equol-producing intestinal bacterium Slackia TM-30 was isolated from healthy human faeces and its effects on urinary phyto-oestrogen, plasma and faecal lipids were assessed in adult mice. RESULTS: The urinary amounts of equol in urine were significantly higher in mice receiving the equol-producing bacterium TM-30 (BAC) group than in the control (CO) group (P < 0.05). However, no significant differences were observed between the urinary amounts of daidzein, dihydrodaidzein, enterodiol, and enterolactone between the BAC and CO groups. No significant differences in the plasma lipids were observed between the two groups. The lipid content (% dry weight) in the faeces sampled on the final day of the experiment tended to be higher in the BAC group than in the CO group (P = 0.07). CONCLUSION: Administration of equol-producing bacterium TM-30 affected the urinary amounts of phyto-oestrogens and the faecal lipid contents of mice. The equol-producing bacterium TM-30 likely influences the metabolism of phyto-oestrogen via changes in the gastrointestinal environment. © 2015 Society of Chemical Industry.

Urinary Phytoestrogens Are Associated with Subtle Indicators of Semen Quality among Male Partners of Couples Desiring Pregnancy.

BACKGROUND: Phytoestrogens have been associated with subtle hormonal changes, although effects on male fecundity are largely unknown. OBJECTIVE: We evaluated associations between male urinary phytoestrogen (isoflavone and lignan) concentrations and semen quality. METHODS: This study was a prospective cohort study of 501 male partners of couples desiring pregnancy and discontinuing contraception. Each participant provided up to 2 semen samples that were analyzed for 35 semen quality endpoints the following day. Linear mixed-effects models were used to estimate associations between baseline urinary phytoestrogen concentrations and semen quality parameters, adjusted for age, body mass index (BMI), research site, and serum lipid and cotinine concentrations. RESULTS: Most associations between urinary phytoestrogens and semen quality parameters were null. However, select individual phytoestrogens were associated with semen quality parameters, with associations dependent on the class of phytoestrogens and modified by BMI. Specifically, genistein and daidzein were associated with a lower percentage of normal sperm and increased abnormalities in semen morphology, with reduced associations observed as BMI increased (P < 0.05) [percentages (95% CIs) of normal morphology by WHO traditional criteria: genistein, main effect: -5.61% (-9.42%, -1.79%); interaction: 0.19% (0.06%, 0.31%) per log unit increase; daidzein, main effect: -5.35% (-9.36%, -1.34%); interaction: 0.18% (0.05%, 0.32%) per log unit increase]. Enterolactone was associated with fewer abnormalities in semen morphometry and morphology and decreased DNA fragmentation, with reduced associations observed as BMI increased (P < 0.05) [percentages (95% CIs) of abnormalities in the neck and midpiece: enterolactone, main effect: -3.35% (-6.51%, -0.19%); interaction: 0.11% (0.01%, 0.21%) per log unit increase]. CONCLUSIONS: These results suggest that male urinary phytoestrogen concentrations characteristic of the US population may be associated with subtle indicators of male fecundity and semen quality but were not associated with couple fecundity.

Urinary isoflavonoids and risk of type 2 diabetes: a prospective investigation in US women.

To examine the association between urinary excretion of isoflavonoids and risk of type 2 diabetes (T2D), we conducted a nested case-control study among 1111 T2D pairs identified during 1995-2008 in the Nurses' Health Study (NHS) and NHSII, who were free of diabetes, CVD and cancer at urine sample collection. Urinary excretion of daidzein and genistein, as well as their metabolites O-desmethylangolensin (O-DMA), dihydrogenistein (DHGE) and dihydrodaidzein (DHDE) was assayed using liquid chromatography MS. Self-reported T2D incident cases were confirmed using a validated questionnaire. Higher urinary excretion of daidzein and genistein was associated with a lower risk of T2D in the combined cohorts. Comparing extreme tertiles of the urinary markers, the OR of T2D were 0·71 (95 % CI 0·55, 0·93) for daidzein and 0·74 (95 % CI 0·56, 0·97) for genistein, although the test for linear trend was not significant for genistein (P trend=0·03 and 0·15, respectively). DMA, DHDE and DHGE were non-significantly associated with a lower T2D risk. The inverse association of daidzein with T2D risk was stronger among post-menopausal women who did not use hormone replacement therapy (P interaction=0·001): the OR was 0·58 (95 % CI 0·34, 0·97) comparing extreme tertiles among these women. In conclusion, urinary excretion of isoflavones was associated with a lower T2D risk in US women, especially among post-menopausal women who did not use hormone. Further research is warranted to replicate these observations among western populations with similarly low overall isoflavone intake.

Soy food frequency questionnaire does not correlate with baseline isoflavone levels in patients with bladder cancer.

BACKGROUND: The isoflavone genistein, a natural soy product with receptor tyrosine kinase-inhibiting activity, as well as phytoestrogenic and other potential anticarcinogenic effects, is being studied as an anticancer agent. Since isoflavones are commonly consumed in food products containing soy proteins, a method to control for baseline isoflavone consumption is needed. METHODS: HPLC was used to evaluate baseline plasma and urine concentrations of isoflavone in fifty-four participants with bladder cancer enrolled on a phase II chemoprevention study of G-2535. The soy food frequency questionnaire was used to assess participant's baseline soy intake. The association between baseline isoflavone concentrations and intakes for genistein and daidzein was assessed by the Spearman's rank correlation coefficient. RESULTS: The majority of participants had no detectable genistein or daidzein in plasma at baseline. The median and range of values were 0 (0-1480) nmol/L for genistein, and 0 (0-1260) nmol/L for daidzein. In urine, the median and range of values were 91.0 (0-9030) nmol/L for genistein and 623 (0-100,000) nmol/L for daidzein. The median and range of weekly estimated genistein intake was 0 (0-236) mg/wk; the median and range of weekly estimated daidzein intake was 0 (0-114) mg/wk. There was no relationship to soy intake as measured by the food frequency questionnaire and baseline isoflavone levels in plasma or urine and the Spearman's rank correlation coefficients were not significant. CONCLUSION: The soy food frequency questionnaire did not correlate with plasma or urine concentrations of either isoflavone. IMPACT: Alternative methods for controlling for soy consumption, including measuring plasma and urine concentrations, in isoflavone chemoprevention trials should be considered.

Malonylglucoside conjugates of isoflavones are much less bioavailable compared with unconjugated ß-glucosidic forms in rats.

Despite considerable interest in the physiologic effects of isoflavones, the in vivo bioavailability of the most common isoflavone forms, malonylglucoside conjugates, has not been determined. Differences in the bioavailability of malonylglucosides compared with the nonconjugated ß-glucoside forms may explain the inconsistent findings regarding the physiologic effects of isoflavones. Therefore, our objective was to determine the effect of malonyl- conjugation on isoflavone bioavailability in an animal model. Malonylgenistin and malonyldaidzin, and their corresponding nonconjugated glucosides, were extracted from soy grits and purified using liquid chromatography. Purity of the isolated forms was confirmed by nuclear magnetic resonance analysis. Male rats were gavaged with malonylgenistin, genistin, malonyldaidzin, or daidzin at a dose of 100 µmol/kg body weight. Blood and urine samples were collected at time intervals ranging from 0 to 48 h. Isoflavone metabolites in plasma and urine were determined using stable isotope dilution-liquid chromatography/mass spectrometry. Comparisons of pharmacokinetic variables were made between nonconjugated and conjugated glucosides and over time of plasma collection. The areas under the time-concentration curve of the metabolites in the plasma obtained after the administration of nonconjugated ß-glucosides were 1 to 6 times higher than those of their respective malonylglucosides (P ≤ 0.05). Additionally, maximum plasma concentration and urinary excretion of isoflavone metabolites were significantly higher (1-9 times; P ≤ 0.05) after the administration of nonconjugated ß-glucosides. To our knowledge, these results demonstrated, for the first time, that nonconjugated ß-glucosides are relatively more bioavailable than their respective malonylglucosides. These differences in the bioavailability of conjugated and nonconjugated ß-glucosides should be considered in future studies focused on the bioactivity of isoflavones.

Higher urinary lignan concentrations in women but not men are positively associated with shorter time to pregnancy.

Phytoestrogens have been associated with subtle hormonal changes, although effects on fecundity are unknown. Our objective was to evaluate the association between male and female urinary phytoestrogen (isoflavone and lignan) concentrations and time to pregnancy (TTP) in a population-based cohort of 501 couples desiring pregnancy and discontinuing contraception. Couples were followed for 12 mo or until pregnancy. Fecundability ORs (FORs) and 95% CIs were estimated after adjusting for age, body mass index, race, site, creatinine, supplement use, and physical activity in relation to female, male, and joint couple concentrations. Models included the phytoestrogen of interest and the sum of the remaining individual phytoestrogens. FORs <1 denote a longer TTP and FORs >1 a shorter TTP. Urinary lignan concentrations were higher, on average, among female partners of couples who became pregnant during the study compared with women who did not become pregnant (median enterodiol: 118 vs. 80 nmol/L; P < 0.10; median enterolactone: 990 vs. 412 nmol/L; P < 0.05) and were associated with significantly shorter TTP in models based on both individual and couples' concentrations (couples' models: enterodiol FOR, 1.13; 95% CI: 1.02, 1.26; enterolactone FOR, 1.11; 95% CI: 1.01, 1.21). Male lignan concentrations were not associated with TTP, nor were isoflavone concentrations. Sensitivity analyses showed that associations observed are unlikely to be explained by potential unmeasured confounding by lifestyle or other nutrients. Our results suggest that female urinary lignan concentrations at levels characteristic of the U.S. population are associated with a shorter TTP among couples who are attempting to conceive, highlighting the importance of dietary influences on fecundity.