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PubMed1995

Methylation profile and amplification of proto-oncogenes in rat pancreas induced with phytoestrogens.

Specific gene hypermethylation has been shown in DNA from neonatal rats exposed to the phytoestrogens, coumestrol, and equol. The pancreas is an organ in which estrogen receptors have been shown to be present. Studies have correlated the development of acute pancreatitis with rising levels of human estrogen binding proteins. Neonatal rats were dosed with 10 or 100 micrograms of coumestrol or equol on postnatal day (PND) 1-10. The animals were sacrificed at Day 15. The pancreas was excised and pancreatic acinar cells isolated for molecular analysis. DNA was isolated from the cells by lysis in TEN-9 buffer supplemented with proteinase K and 0.1% SDS. High molecular weight (HMW) DNA was digested with the methylated DNA specific restriction enzymes, Hpa II and Msp I, for determination of methylation profiles. Both coumestrol and equol at high doses caused hypermethylation of the c-H-ras proto-oncogene. No hypermethylation or hypomethylation was observed in the proto-oncogenes, c-myc or c-fos. Methylation is thought to be an epigenetic mechanism involved in the activation (hypomethylation) or inactivation (hypermethylation) of cellular genes which are known to play a role in carcinogenesis. Epidemiology studies have shown that equol may have anti-carcinogenic effects on some hormone-dependent cancers. Additional studies are needed to further understand the role of phytoestrogens and methylation in relation to pancreatic disorders.

Animals↗
PubMed2004

Mammographic density in relation to daidzein-metabolizing phenotypes in overweight, postmenopausal women.

Circulating hormones are associated with mammographic density, an intermediate marker of breast cancer risk. Differences in circulating hormones, including estrone and testosterone, have been observed in premenopausal women based on their capacity to metabolize daidzein, an isoflavone found predominantly in soybeans. Equol and O-desmethylangolensin (O-DMA) are products of intestinal bacterial metabolism of daidzein. There is interindividual variability in the capacity to produce daidzein metabolites; individuals can be equol producers or non-producers and O-DMA producers or non-producers. We tested the hypothesis that daidzein-metabolizing phenotypes are associated with mammographic density. Participants were recruited from among 92 sedentary, postmenopausal women, ages 50 to 75 years, who participated in a 1-year physical activity intervention. Pre-intervention mammographic density was determined using a computer-assisted, gray-scale thresholding technique. Fifty-five of these women consumed supplemental soy protein (>10 mg daidzein/d) for 3 days and collected a first-void urine sample on the fourth day to determine daidzein-metabolizing phenotypes. Equol and O-DMA concentrations were measured using gas chromatography-mass spectrometry. Associations between daidzein-metabolizing phenotypes and percent mammographic density were adjusted for age, maximum adult weight, gravidity, family history of breast cancer, and serum follicle-stimulating hormone and free testosterone concentrations. Mammographic density was 39% lower in equol producers compared with non-producers (P = 0.04). O-DMA producers had mammographic density 69% greater than non-producers (P = 0.05). These results suggest that particular intestinal bacterial profiles are associated with postmenopausal mammographic density, and these associations are not entirely explained by differences in reproductive or anthropometric characteristics or circulating hormones.

Aged↗
PubMed2002

In vitro isoflavone supplementation reduces hydrogen peroxide-induced DNA damage in sperm.

Isoflavones are plant compounds, proposed to have health benefits in a variety of human diseases, including coronary heart disease and endocrine-responsive cancers. Their physiological effects include possible antioxidant activity, therefore suggesting a role for isoflavones in the prevention of male infertility. The aim of this study was to test the antioxidant effects of the isoflavones genistein and equol on sperm DNA integrity, assessed in vitro after hydrogen peroxide-mediated damage, using the comet assay. Pre-treatment with genistein or equol at doses of 0.01-100 micromol/l significantly protected sperm DNA against oxidative damage. Both ascorbic acid (10-600 micromol/l) and alpha-tocopherol (1-100 micromol/l) also protected. Compared with ascorbic acid and alpha-tocopherol, added at physiological concentrations, genistein was the most potent antioxidant, followed by equol, ascorbic acid, and alpha-tocopherol. Genistein and equol added in combination were more protective than when added singly. Based on these preliminary data, which are similar to those observed previously in lymphocytes, these compounds may have a role to play in antioxidant protection against male infertility.

Anticarcinogenic Agents↗
PubMed2002

Time-resolved fluoroimmunoassay of plasma and urine O-desmethylangolensin.

We present a method for the determination of the phytoestrogen metabolite O-desmethylangolensin (O-DMA) in plasma (serum) and in urine. O-DMA is a metabolite of daidzein, which occurs in soybeans. It has been suggested that isoflavones may afford protection against breast and prostate cancer and therefore, also the metabolites are of interest. The method is based on time-resolved fluoroimmunoassay (TR-FIA) using a europium chelate as a label. After the synthesis of 4"-O-carboxymethyl-O-DMA, this compound is coupled to bovine serum albumin, and then used as antigen in immunization of rabbits. The tracers with the europium chelate are synthesized using the same 4"-O-derivative of the alpha-methyldeoxybenzoin. After enzymatic hydrolysis and ether extraction the immunoassay is carried out by time resolved fluoroimmunoassay (TR-FIA). Cross-reactivity was tested with angolensin, dihydrogenistein, dihydrodaidzein, equol, 6'-OH-angolensin, trans-4-OH-equol, 6'-OH-O-DMA, cis-4-OH-equol and 5-OH-equol. The antiserum cross-reacted only with angolensin. This cross-reactivity seems not to influence the results, which were highly specific. Plasma samples are hydrolyzed and extracted. Urine samples are analyzed directly after hydrolysis without extraction. The correlation coefficient between the plasma TR-FIA results and the GC-MS results was high; r value was 0.985. The correlation coefficient between the urine TR-FIA results and the GC-MS results was high over the entire range of concentrations (0-1500 nmol/l); r value was 0.976, but lower in the low concentration range (0-100 nmol/l), i.e. value was 0.631. The intra-assay coefficients of variation (CVs) for plasma O-DMA concentrations and for urine O-DMA concentrations at three different concentrations varied 2.8-7.7 and 3.0-6.0%, respectively and the inter-assay CVs varied 3.8-8.9 and 4.4-6.6%, respectively. The working range of the plasma and urine O-DMA assays was 0.5-512 nmol/l.

Animals↗
PubMed2005

Soy processing affects metabolism and disposition of dietary isoflavones in ovariectomized BALB/c mice.

Soy foods and nutritional supplements are widely consumed for potential health benefits. It was previously shown that isoflavone-supplemented diets, which contained equal genistein equivalents, differentially stimulated mammary tumor growth in athymic mice based on the degree of processing. This paper reports plasma pharmacokinetic analysis and metabolite identification using the parental mouse strain fed the same diets, which contained genistin, mixed isoflavones, Novasoy, soy molasses, or soy flour plus mixed isoflavones. Whereas the degree of soy processing did affect several parameters reflecting isoflavone bioavailability and gut microflora metabolism of daidzein to equol, stimulation of tumor growth correlated significantly with only the plasma concentration of aglycon genistein produced by the diets. This conclusion is consistent with the known estrogen agonist activity of genistein aglycon on mammary tumor growth. Conversely, plasma equol concentration was inversely correlated with the degree of soy processing. Although antagonism of genistein-stimulated tumor growth by equol could explain this result, the very low concentration of aglycon equol in plasma (12-fold lower relative to genistein) is inconsistent with any effect. These findings underscore the importance of food processing, which can remove non-nutritive components from soy, on the pharmacokinetics and pharmacodynamics of isoflavones. Such changes in diet composition affect circulating, and presumably target tissue, concentrations of genistein aglycon, which initiates estrogen receptor-mediated processes required for the stimulation of tumor growth in a mouse model for postmenopausal breast cancer.

Animals↗
PubMed1998

Sex and long-term soy diets affect the metabolism and excretion of soy isoflavones in humans.

Soybean consumption may be protective against hormone-dependent cancers, possibly in part because of the isoflavones daidzein and genistein, which are weakly estrogenic. This paper reviews our studies of the metabolism and disposition of these phytoestrogens in humans. During 1 mo of daily soy ingestion in a metabolic unit [1.065 L (36 oz) soymilk, providing 80-210 mg of each isoflavone daily], women initially excreted more isoflavone conjugates in urine than did men. Recoveries of conjugates of genistein, daidzein, and equol were 24%, 66%, and 28% of the amounts ingested in women, respectively, and 15%, 47%, and 15%, respectively, of those in men. A progressive decrease in urinary excretion of genistein and daidzein was observed in women but not in men during the study. At least 10% of ingested daidzin was excreted in urine as equol conjugate in one man and one woman after the first soy ingestion. Three more women but no more men developed the ability to produce and excrete large amounts of equol. Absorption rate constants (k(e)) of the isoflavones were estimated to be 0.24-0.50 h(-1). The elimination rates (k(e)) for genistein, daidzein, and equol were 0.1, 0.16, and 0.08 h(-1), respectively, in women and 0.19, 0.25, and 0.13 h(-1), respectively, in men. Thus, the excretion half-life values of genistein were longer in women (7, 4, and 9 h, respectively) than in men (4, 3, and 5 h, respectively) after the first soy ingestion. The excretion half-life shortened progressively in women but lengthened progressively in men over the study period. Thus, isoflavone metabolism and disposition were affected by the duration of soy ingestion and by sex.

Adult↗
PubMed2006

Metabolic phenotype of isoflavones differ among female rats, pigs, monkeys, and women.

Various physiologic effects of soy food consumption have been attributed to the estrogenic actions of isoflavones. The order of estrogen receptor binding potency of soy-derived isoflavone aglycones is equol > genistein > daidzein, and their conjugates are less potent. Because the metabolic profile may be an important determinant of bioactivity after soy intake, we studied the serum and urine isoflavone concentrations in 3 animal models and compared them with isoflavone profiles in women. Female Sprague-Dawley rats, Hampshire/Duroc Cross pigs, cynomolgus monkeys, and women were fed diets containing soy protein isolate. Isoflavones and their metabolites were measured by LC-MS or electrochemical detection. Equol represented approximately 77 and 52% (molar ratio) of summed serum isoflavones (isoflavones plus metabolites) in rats and cynomolgus monkeys, respectively. Equol was undetectable in pig serum and human plasma, but daidzein and genistein contributed >88% of summed circulating isoflavones. Monkey and rat urine contained high levels of aglycones (>85% and >32%, respectively), whereas pigs and women excreted isoflavone mainly in the form of glucuronides (>80%), with <10% as aglycones. Isoflavones in human plasma were predominantly glucuronides (75%) with 24% as sulfates and <1% as aglycones; in monkey serum, however, 64% of isoflavones were sulfates, 30% glucuronides, and 6% aglycones. Equol was also a major serum metabolite of 6-mo-old rhesus monkeys (80% of summed isoflavones). Thus, there were significant interspecies differences in isoflavone metabolism, and the overall metabolic profile of pigs was closer to that of women than that of rats or monkeys.

Animals↗
PubMed2006

Soy isoflavones increase preprandial peptide YY (PYY), but have no effect on ghrelin and body weight in healthy postmenopausal women.

BACKGROUND: Soy isoflavones show structural and functional similarities to estradiol. Available data indicate that estradiol and estradiol-like components may interact with gut "satiety hormones" such as peptide YY (PYY) and ghrelin, and thus influence body weight. In a randomized, double-blind, placebo-controlled, cross-over trial with 34 healthy postmenopausal women (59 +/- 6 years, BMI: 24.7 +/- 2.8 kg/m2), isoflavone-enriched cereal bars (50 mg isoflavones/day; genistein to daidzein ratio 2:1) or non-isoflavone-enriched control bars were consumed for 8 weeks (wash-out period: 8-weeks). Seventeen of the subjects were classified as equol producers. Plasma concentrations of ghrelin and PYY, as well as energy intake and body weight were measured at baseline and after four and eight weeks of each intervention arm. RESULTS: Body weight increased in both treatment periods (isoflavone: 0.40 +/- 0.94 kg, P < 0.001; placebo: 0.66 +/- 0.87 kg, P = 0.018), with no significant difference between treatments. No significant differences in energy intake were observed (P = 0.634). PYY significantly increased during isoflavone treatment (51 +/- 2 pmol/L vs. 55 +/- 2 pmol/L), but not during placebo (52 +/- 3 pmol/L vs. 50 +/- 2 pmol/L), (P = 0.010 for treatment differences, independent of equol production). Baseline plasma ghrelin was significantly lower in equol producers (110 +/- 16 pmol/L) than in equol non-producers (162 +/- 17 pmol/L; P = 0.025). CONCLUSION: Soy isoflavone supplementation for eight weeks did not significantly reduce energy intake or body weight, even though plasma PYY increased during isoflavone treatment. Ghrelin remained unaffected by isoflavone treatment. A larger and more rigorous appetite experiment might detect smaller differences in energy intake after isoflavone consumption. However, the results of the present study do not indicate that increased PYY has a major role in the regulation of body weight, at least in healthy postmenopausal women.

Aged↗
PubMed2005

Association of serum phytoestrogen concentration and dietary habits in a sample set of the JACC Study.

BACKGROUND: Phytoestrogens may be associated with a reduced risk of hormone dependent neoplasms such as prostate and breast cancers. We tried to determine the validity of the association between serum phytoestrogen concentrations and dietary habits obtained from a food frequency questionnaire used in the Japan Collaborative Cohort Study (JACC Study) for Evaluation of Cancer Risk sponsored by the Ministry of Education, Science, Sports and Culture of Japan (Monbusho). METHODS: The subjects were 151 male controls who were selected for a nested case-control study for evaluating prostate cancer risk as part of the JACC Study. Dietary habits were determined using a food frequency questionnaire at baseline, and the concentrations of genistein, daidzein, and equol in frozenstored serum samples assayed in 2002 were compared. RESULTS: Tofu intake showed a significant association with the serum concentrations of genistein and daidzein (Spearman's correlation coefficients (rs)=0.30 and 0.27, respectively), and miso soup showed a slight association with serum concentrations of these phytoestrogens. In contrast, serum concentrations of equol were not associated with dietary intake of tofu and miso soup. After adjustment for serum daidzein concentration, serum equol concentration was associated with the intake of foods containing fat, meat, and coffee, but not green tea. CONCLUSIONS: Serum genistein and daidzein concentrations were significantly associated with dietary intake of tofu, and slightly with intake of miso soup. Consumption of fat, meat, and coffee may be associated with equol production by intestinal microflora in this sample set.

Adult↗
PubMed2004

Phytoestrogen concentrations in serum and spot urine as biomarkers for dietary phytoestrogen intake and their relation to breast cancer risk in European prospective investigation of cancer and nutrition-norfolk.

Subjects of this study consisted of 333 women (aged 45-75 years) drawn from a large United Kingdom prospective study of diet and cancer, the European Prospective Investigation of Cancer and Nutrition-Norfolk study. Using newly developed gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry methods incorporating triply (13)C-labeled standards, seven phytoestrogens (daidzein, genistein, glycitein, O-desmethylangolensin, equol, enterodiol, and enterolactone) were measured in 114 spot urines and 97 available serum samples from women who later developed breast cancer. Results were compared with those from 219 urines and 187 serum samples from healthy controls matched by age and date of recruitment. Dietary levels were low, but even so, mean serum levels of phytoestrogens were up to 600 times greater than postmenopausal estradiol levels. Phytoestrogen concentrations in spot urine (adjusted for urinary creatinine) correlated strongly with that in serum, with Pearson correlation coefficients > 0.8. There were significant relationships (P < 0.02) between both urinary and serum concentrations of isoflavones across increasing tertiles of dietary intakes. Urinary enterodiol and enterolactone and serum enterolactone were significantly correlated with dietary fiber intake (r = 0.13-0.29). Exposure to all isoflavones was associated with increased breast cancer risk, significantly so for equol and daidzein. For a doubling of levels, odds ratios increased by 20-45% [log(2) odds ratio = 1.34 (1.06-1.70; P = 0.013) for urine equol, 1.46 (1.05-2.02; P = 0.024) for serum equol, and 1.22 (1.01-1.48; P = 0.044) for serum daidzein]. These estimates of risk are similar to those established for estrogens and androgens in postmenopausal breast cancer but need confirmation in larger studies.

Adult↗
PubMed1976

Composition of some urinary calculi of ruminants in Western Australia.

Forty ruminant urinary calculi, selected as being essentially inorganic and mainly obtained from sheep grazing in the drier wheatbelt areas of Western Australia, were examined by optical and X-ray diffraction techniques. Four mineral types-silica (SiO2-nH2O), weddellite (CaC2O4-2H2O), calcite (CaCO3) and aragonite (CaCO3)--were found. These minerals were present respectively in 30, 17, 13 and 1 of the 40 calculi examined and were the sole component in 12, 0, 7, and 0 calculi. One calculus was found to be composed of organic material which was subsequently shown to consist mainly of 4'-O methyl equol (4'-methoxy-7-isoflavanol, C16H16O3) with a small amount of equol and a trace of formononetin. This is the first report of a calculus of this composition. Determinative data useful for identification of 4'o-methyl equol, equol and a related substance are presented in an appendix.

Animals↗
PubMed1986

Identification of lignans and phytoestrogens in urine of chimpanzees.

It was recently observed that the urinary excretion of animal lignans is low in postmenopausal breast cancer patients compared to normal omnivorous and vegetarian women. In addition, the mean excretion of the isoflavonic phytoestrogen equol tended to be lower. Because nonhuman primates appear to be remarkably resistant to the carcinogenic effect of estrogens, we investigated the possible occurrence of lignans and phytoestrogens in the urine of chimpanzees on their regular diet. Five major diphenols were isolated and identified by capillary gas chromatography and mass spectrometry by comparison with synthesized authentic reference compounds. Three of these compounds, the phytoestrogen equol and its precursor daidzein, the lignan enterolactone, were according to preliminary assays excreted in very large amounts. In addition, the lignan enterodiol and the daidzein metabolite O-desmethylangolensin were identified. It is concluded that the chimpanzee excretes both isoflavonic phytoestrogens and lignans in urine, apparently in high concentrations. It is suggested that these compounds may play a role in the maintenance of the resistance against carcinogenic effects of estrogens, which nonhuman primates possess, because both equol and enterolactone have been shown to have antiestrogenic properties in animals. However, much further work is necessary before the possible biological role of these compounds may be established.

4-Butyrolactone↗
PubMed1993

Metabolites of dietary (soya) isoflavones in human urine.

This study was undertaken to better understand the metabolic fate of dietary isoflavones in humans. Twelve volunteers were challenged with soya flour and urinary diphenol levels were then determined by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The presence of previously described urinary diphenols was confirmed, i.e. the isoflavones, daidzein and genistein; the isoflavonoid metabolites, equol, dihydrodaidzein (Int-O-D), O-desmethyl-angolensin (O-Dma); the lignan, enterolactone. Diphenols detected for the first time were the isoflavone, glycitein and five novel isoflavonoid metabolites which are tentatively identified as 6'-hydroxy-O-desmethylangolensin (6' OH-O-Dma), dihydrogenistein (Int-O-G), dehydro-O-desmethylangolensin (dehydro-O-Dma) and two isomers of tetrahydrodaidzein. Urinary excretion rates of the three isoflavones (daidzein, genistein, glycitein) over a 3-day period following soya challenge showed moderate variation (4x, 6x and 12x, respectively) between the 12 individuals suggesting some individual variabilities in ability to deconjugate and to absorb dietary isoflavones. However, urinary excretion rates of each of three major isoflavonoid metabolites (equol, O-Dma, 6' OH-O-Dma) showed more marked variation (922x, 17x, 15x, respectively); while some of this variability may reflect varying individual ability to ferment dietary isoflavones per se, an inverse relationship was found between urinary levels of equol and both O-Dma and 6' OH-O-Dma suggesting individual variability in the preferred metabolic pathways of dietary isoflavones.

Adult↗
PubMed2004

Isoflavones stimulate estrogen receptor-mediated core histone acetylation.

The isoflavones genistein and daidzein and the daidzein metabolite equol have been reported to interact with estrogen receptors (ERs). Some studies indicate that they behave clinically like estrogen in some estrogen-deficiency diseases. However, the detailed molecular mechanism used by these compounds to create beneficial effects in patients with estrogen-related diseases has not been clarified. Using histone acetyltransferase (HAT) assay, we found that equol, genistein, and AglyMax had significant effects on ERalpha-mediated histone acetylation. Although 17beta-estradiol (E2)-dependent HAT activity of steroid receptor coactivators 2 (SRC2) and p300 mediated by ERbeta could be detected, it was weaker than that mediated by ERalpha. Equol, genistein, AglyMax, and daidzein all markedly stimulated ERbeta-mediated histone acetylation. On the other hand, anti-estrogenic compounds ICI 182,780 (ICI) and tamoxifen (TA) did not have an effect on HAT activity mediated by either ERalpha or ERbeta. Our data indicate that estrogenic ligands exert their effects by elevating histone acetylation and coactivator activity of ER, and suggest that the risk of estrogen-related diseases might be reduced by a sufficient amount of genistein or AglyMax supplements.

Acetylation↗
PubMed1995

Urinary isoflavonoid phytoestrogen and lignan excretion after consumption of fermented and unfermented soy products.

OBJECTIVE: To compare the effects of consumption of fermented and unfermented soy products on excretion of urinary isoflavonoid phytoestrogens and lignans in healthy men. DESIGN: A randomized, crossover trial consisting of two 9-day feeding periods following 5 days of baseline data collection. SUBJECTS: Healthy men, aged 20 to 40 years, were recruited from the University of Minnesota Twin Cities community. Of the 22 subjects who began the study, 17 completed all feeding periods. INTERVENTIONS: Fermented soy product (112 g tempeh) or unfermented soy (125 g soybean pieces) was consumed during each controlled feeding period. MAIN OUTCOME MEASURE: Urine samples collected while subjects consumed their habitual diets and on the last 3 days of each feeding period were analyzed for isoflavonoid and lignan content by isotope dilution gas chromatography-mass spectrometry. STATISTICAL ANALYSIS PERFORMED: Comparisons of isoflavonoid and lignan excretion were analyzed using the general linear model procedure. Orthogonal contrasts were used to determine treatment differences of interest. RESULTS: Urinary excretion of isoflavonoids (equol, O-desmethylangolensin [O-DMA], daidzein, genistein) was higher and excretion of lignans (enterodiol, enterolactone) was lower when subjects consumed soy-supplemented diets than when they consumed their habitual diets (P < .05). Urinary isoflavonoid excretion and lignan excretion were similar when subjects consumed tempeh and soybean pieces diets; however, recovery of daidzein and genistein was significantly higher when subjects consumed the tempeh diet than when they consumed the soybean pieces diet (P < .002). When fed soy, 5 of 17 subjects excreted high amounts of equol. These five subjects tended to excrete less O-DMA and daidzein than the 12 subjects who excreted low amounts of equol (P < .06). CONCLUSIONS: Fermentation of soy decreased the isoflavone content of the product fed but increased the urinary isoflavonoid recovery. This finding suggests that fermentation increases availability of isoflavones in soy.

4-Butyrolactone↗
PubMed1998

Assessment of isoflavonoid concentrations in Australian bovine milk samples.

There is considerable interest in the possibility that diet-derived isoflavonoids may help in protection against a number of chronic diseases common in Western society. Based on animal studies, however, concerns have been raised that consumption of isoflavonoids by infants and young children may be undesirable. Clover contains isoflavonoids and therefore may represent, via milk, a source of isoflavonoids in the human diet. In this study the concentrations of daidzein (7, 4'-dihydroxyisoflavone), genistein (5, 7, 4'-trihydroxyisoflavone) and equol (7-hydroxy-(4'-hydroxyphenyl)chroman) were measured using HPLC in cows' milk samples obtained from 76 farms in three Australian states. In addition, concentrations were measured in samples collected from one South Australian factory both before and after pasteurization. Concentrations in all samples were found to be extremely low. The mean daidzein concentration was < 5 ng/ml. Mean genistein concentrations ranged from just detectable (approximately 2 ng/ml) in Victorian samples collected during summer to 20-30 ng/ml in samples from all states collected during spring when isoflavonoid-containing clover is most dominant in pasture. Mean equol concentrations ranged from 45 +/- 10 ng/ml in Victorian farm samples collected during summer to 293 +/- 52 ng/ml in Western Australian samples collected in spring. The mean concentrations of genistein and equol in post-pasteurization samples collected in spring were approximately double those for samples collected in autumn. Pasteurization had no effect on isoflavonoid concentrations. We conclude that the concentrations of isoflavonoids in Australian cows' milk are low and are therefore unlikely to have any pronounced biological effects in human consumers.

Animals↗
PubMed2006

Phyto-oestrogen intake in Scottish men: use of serum to validate a self-administered food-frequency questionnaire in older men.

OBJECTIVE: To study dietary intake and serum concentrations of isoflavones in order to provide relative validation of isoflavone intake estimates from the Scottish Collaborative Group - Food-Frequency Questionnaire (SCG-FFQ). DESIGN: Validation study. SETTING: Southern Scotland. METHOD: Dietary intake of isoflavones was estimated using the semiquantitative SCG-FFQ and rank correlation and Kappa statistics were used for the relative validation of intakes against serum isoflavone concentrations in 203 male participants who were population controls in a case-control study of diet and prostate cancer. RESULTS: The median intake of isoflavones (daidzein and genistein) was 1.0mg/day (l-QR 0.6-1.8). The median serum concentration of genistein was 33.79 nmol/l (I-QR 14.12-64.93), nearly twice that of daidzein (18.00 nmol/l, I-QR 8.26-29.45). Equol was detected in 49% of subjects; in these subjects the median was 0.67 nmol/l (I-QR 0.34-1.51). Isoflavone intake was significantly correlated with serum concentrations of daidzein (p = 0.24, P = 0.001), genistein (p = 0.26, P < 0.001) and total isoflavonoids (sum of daidzein, genistein and equol) ( p = 0.27, P < 0.001). Whereas values for weighted Kappa ranged from 0.16 (P = 0.002) for daidzein and equol combined to 0.22 (P < 0.001) for genistein. CONCLUSIONS: These results demonstrate the suitability of the SCG-FFQ to rank usual isoflavone intakes in older Scottish men, a population observed to have low consumption of soy foods.

Aged↗
PubMed2006

Isoflavonoid photoprotection in mouse and human skin is dependent on metallothionein.

Previous studies report that selected topical isoflavonoids are immunoprotective in both mice and humans, when applied following UV irradiation. Isoflavonoids have documented antioxidant activity, but their mechanism of immunomodulation remains unclear. This study examines whether photoimmunoprotection by the isoflavonoids might result from their interaction with one cutaneous antioxidant known to modulate UV photodamage, metallothionein (MT). In mice bearing a null mutation for MT-I and -II, we found that immunoprotection by the isoflavonoid 4',7-dihydroxyisoflavane (equol) against solar-simulated UV radiation (SSUV) or exogenous cis-urocanic acid was abrogated. Topical equol did not activate MT expression in normal mouse skin, but markedly enhanced the increase in MT expression in murine epidermis following SSUV irradiation. Normal human skin, unlike murine, expressed MT in the basal epidermis. Following SSUV irradiation, topical application of the related synthetic isoflavonoid NV-07alpha to human skin also markedly enhanced epidermal MT expression. The NV-07alpha has been reported previously to protect humans against the UV suppression of Mantoux reactions. Thus, epidermal MT expression appears to protect against photoimmunosuppression in both human and mouse skin. We speculate that equol and its related derivative NV-07alpha may activate the MT gene synergistically with SSUV, to produce the enhanced immunoprotective effect.

Animals↗