Serum Isoflavone Concentrations Research Articles

Feeding Soy Protein Concentrates with Low and High Isoflavones Alters 9 and 18 Weeks Serum Isoflavones and Inflammatory Protein Levels in Lean and Obese Zucker Rats

Soy's anti-inflammatory properties contribute to the health benefits of soy foods. This study was designed to investigate the bioavailability of soy isoflavones and whether the isoflavone content of soy protein concentrate diet would affect serum inflammatory proteins in an obese (fa/fa) Zucker rat model. Six-week-old male lean (L) and obese (O) Zucker rats were fed a casein control diet (C), soy protein concentrate with low isoflavones (SPC-LIF), or soy protein concentrate with high isoflavones (SPC-HIF) (7 rats/dietary group) before being killed at 9 and 18 weeks. Serum samples were analyzed for isoflavones and inflammatory proteins. At both time points, serum total (aglycone + conjugates) genistein, daidzein, and equol concentrations were significantly higher in L-SPC-HIF and O-SPC-HIF groups compared with L-SPC-LIF and O-SPC-LIF groups, respectively, and were not detectable in either L-C or O-C groups. At week 9, serum C-reactive protein (CRP) concentration was significantly lower in O-SPC-HIF group compared with O-C and O-SPC-LIF group, whereas proteins tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels did not differ between any groups. At week 18, serum CRP levels in both O-SPC-HIF and O-SPC-LIF groups were significantly lower compared with the O-C group. TNF-α level was higher in the O-SPC-LIF group compared with both O-C and O-SPC-HIF groups, whereas IL-6 levels were not different between any groups. Taken together, feeding Zucker rats SPC-LIF and SPC-HIF diets led to different serum isoflavone concentrations in both L and O Zucker rats and altered CRP and TNF-α levels in obese Zucker rats compared with controls.

Longer-term soy nut consumption improves vascular function and cardiometabolic risk markers in older adults: Results of a randomized, controlled cross-over trial

Soy foods may contribute to the beneficial health effects of healthy plant-based diets on the risk to develop cardiovascular disease (CVD). However, their effects on vascular function have hardly been studied. To investigate longer-term effects of soy nut consumption on vascular function and cardiometabolic risk markers in healthy older men and women. Twenty-three healthy participants (age: 60-70 years; BMI: 20-30kg/m2) participated in a randomized, controlled, single-blinded cross-over trial with an intervention (67g/day of soy nuts providing 25.5g protein and 174mg isoflavones) and control period (no nuts) of 16 weeks, separated by eight weeks wash-out. Adults followed the Dutch food-based dietary guidelines. No serious adverse events were reported and the soy nut regime was well tolerated. Body weights remained stable during the whole study. A higher protein (3.1 energy percent [En%]) and a lower carbohydrate intake (2.0 En%) was observed during the intervention period. Total fat intake was comparable, but that of saturated (-1.3 En%), cis-monounsaturated (-1.5 En%) and cis-polyunsaturated fatty acids (+1.9 En%) differed. Serum isoflavone concentrations were higher after the intervention as compared with the control period (daidzein: 127.8ng/mL; 95% CI: 74.3-181.3ng/mL; p<0.001 and genistein: 454.2ng/mL; 95% CI: 266.6-641.8ng/mL; p<0.001). Brachial artery flow-mediated vasodilation was 1.48 percent points (pp; 95% CI: 0.08-2.89 pp; p=0.040) higher following soy nut intake. The carotid artery reactivity response and arterial stiffness did not differ. Serum LDL-cholesterol was lower (0.17mmol/L; 95% CI: 0.02-0.32mmol/L; p=0.027), while HDL-cholesterol and triacylglycerol concentrations were comparable. Mean arterial pressure (MAP) was lower (3mmHg; 95% CI: 0-6mmHg; p=0.035). Longer-term soy nut intake as part of a healthy diet improved endothelial function, LDL-cholesterol concentrations and MAP levels, suggesting mechanisms by which an increased soy food intake beneficially affects CVD risk in older adults. Registered under ClinicalTrials.gov Identifier no. NCT03627637.

Longer-term soy nut consumption improves cerebral blood flow and psychomotor speed: results of a randomized, controlled crossover trial in older men and women

ABSTRACTBackgroundEffects of soy foods on cerebral blood flow (CBF)—a marker of cerebrovascular function—may contribute to the beneficial effects of plant-based diets on cognitive performance.ObjectivesWe aimed to investigate longer-term effects of soy nut consumption on CBF in older adults. Changes in 3 different domains of cognitive performance were also studied.MethodsTwenty-three healthy participants (age: 60–70 y; BMI: 20–30 kg/m2) participated in a randomized, controlled, single-blinded crossover trial with an intervention (67 g/d of soy nuts providing ∼25.5 g protein and 174 mg isoflavones) and control period (no nuts) of 16 wk, separated by an 8-wk washout period. Adults followed the Dutch food-based dietary guidelines. At the end of each period, CBF was assessed with arterial spin labeling MRI. Psychomotor speed, executive function, and memory were assessed using the Cambridge Neuropsychological Test Automated Battery (CANTAB).ResultsNo serious adverse events were reported, and soy nut intake was well tolerated. Body weights remained stable during the study. Serum isoflavone concentrations increased (daidzein mean difference ± SD: 128 ± 113 ng/mL, P < 0.001; genistein: 454 ± 256 ng/mL, P < 0.001), indicating excellent compliance. Regional CBF increased in 4 brain clusters located in the left occipital and temporal lobes (mean ± SD increase: 11.1 ± 12.4 mL · 100 g−1 · min−1, volume: 11,296 mm3, P < 0.001), bilateral occipital lobe (12.1 ± 15.0 mL · 100 g−1 · min−1, volume: 2632 mm3, P = 0.002), right occipital and parietal lobes (12.7 ± 14.3 mL · 100 g−1 · min−1, volume: 2280 mm3, P = 0.005), and left frontal lobe (12.4 ± 14.5 mL · 100 g−1 · min−1, volume: 2120 mm3, P = 0.009) which is part of the ventral network. These 4 regions are involved in psychomotor speed performance, which improved as the movement time reduced by (mean ± SD) 20 ± 37 ms (P = 0.005). Executive function and memory did not change.ConclusionsLonger-term soy nut consumption may improve cerebrovascular function of older adults, because regional CBF increased. Effects may underlie observed improvements in psychomotor speed.This trial was registered at clinicaltrials.gov as NCT03627637.

Longer-Term Soy Nut Consumption Improves Vascular Function and Cardiometabolic Risk Markers in Older Adults: Results of a Randomized, Controlled Cross-Over Trial

Abstract Objectives Soy foods may contribute to the beneficial effects of plant-based diets on cardiovascular disease (CVD) risk. However, their effects on vascular function have hardly been investigated. The objective was to investigate if longer-term soy nut consumption improves vascular function and cardiometabolic health in older adults. Methods Twenty-three apparently healthy participants (60–70 years; BMI between 20–30 kg/m2) participated in a randomized, controlled, single-blinded cross-over trial with an intervention (67 g of soy nuts daily providing 25.5 g soy protein) and control period (no nuts) of 16 weeks, separated by eight weeks wash-out. Volunteers followed the Dutch food-based dietary guidelines. At baseline and at 8 and 16 weeks anthropometric measurements and fasting blood samples were collected. Markers of vascular function (i.e., endothelial function, arterial stiffness, and microvascular structure) were assessed at week 16. Results No serious adverse events were reported and the soy nut regime was well tolerated. Body weight remained stable. Serum isoflavone concentrations, a marker of compliance, increased after the intervention period (daidzein: 128.3 ng/mL; 95% CI: 72.6–183.9 ng/mL; P &amp;lt; 0.001 and genistein: 439.8 ng/mL 95% CI: 246.7–632.9 ng/mL; P &amp;lt; 0.001). The brachial artery flow-mediated vasodilation (FMD) response increased by 1.49 pp (95% CI: 0.03–2.95 pp; P = 0.046) following the soy intervention, but no effect was found on the carotid artery reactivity (CAR) response. Arterial stiffness, assessed by carotid-to-femoral pulse wave velocity (PWVc-f), was unchanged. Retinal arteriolar calibers (CRAE), a measure for microvascular structure, tended to improve by 1.42 mm (95% CI: −0.05–2.90 mm; P = 0.059). Soy consumption also lowered serum LDL-cholesterol concentrations by 0.17 mmol/L (95% CI: 0.02–0.32 mmol/L; P = 0.027). HDL-cholesterol and triacylglycerol (TAG) did not change. Finally, office SBP and DBP decreased by 4 mmHg (95% CI: 0–8 mmHg; P = 0.034) and 2 mmHg (95% CI: 1–4 mmHg; P = 0.005), respectively. Conclusions A longer-term daily intake of soy nuts improved endothelial function, office blood pressure, and serum LDL-cholesterol concentrations, suggesting mechanisms by which an increased soy food intake beneficially affects CVD risk in older adults. Funding Sources This study was supported by a grant from the Alpro Foundation.

Serum isoflavones and lignans and odds of breast cancer in pre- and postmenopausal Chinese women.

Isoflavones and lignans are phytoestrogens present in plant-based foods, which have a potential preventive effect on breast carcinogenesis. The effects of phytoestrogens on breast cancer may differ according to the hormonal environment. This case-control study aimed to investigate the association between serum phytoestrogens and odds of breast cancer among Chinese pre- and postmenopausal women. A total of 792 cases and 813 age-matched controls were included. Serum isoflavone (daidzein, genistein, glycitein, equol, and formononetin) and lignan (enterodiol and enterolactone) concentrations were measured using a liquid chromatography-tandem mass spectrometry method. Significant inverse associations were found between serum total soy isoflavone precursors, daidzein, genistein, formononetin, total lignans, enterodiol, enterolactone, and the odds of breast cancer in premenopausal but not postmenopausal women. For premenopausal women, the adjusted odds ratios (95% confidence intervals) for the highest versus the lowest serum concentration groups were 0.60 (0.41-0.87) for total soy isoflavones precursors, 0.64 (0.44-0.93) for daidzein, 0.62 (0.43-0.90) for genistein, 0.49 (0.35-0.68) for formononetin, 0.38 (0.25-0.57) for total lignans, 0.49 (0.33-0.73) for enterodiol, and 0.49 (0.33-0.74) for enterolactone. However, the interaction between serum phytoestrogens and menopausal status on odds of breast cancer was statistically significant only for daidzein. No significant association was found between serum equol or gycitein and the odds of breast cancer among either pre- or postmenopausal women. Higher levels of certain serum isoflavones and lignans were associated with reduced odds of breast cancer in premenopausal women, but the interaction was statistically significant only for daidzein.

The Effect of Dried Beancurd on Bone Mineral Density in Postmenopausal Chinese Women: A 2-Year Randomized Controlled Trial.

Soy foods contain several components such as isoflavones, calcium and protein that potentially modulate bone turnover and increase bone mineral density (BMD) in postmenopausal women. The study is to evaluate the effect of dried beancurd supplementation on skeletal health in postmenopausal Chinese women. Three hundred postmenopausal women aged 50-65years were assigned into two groups, receiving 100g dried beancurd or rice cake a day for 2years. BMD at the lumbar spine and right proximal femur were measured with a dual-energy X-ray absorptiometry. The bone turnover biomarkers of serum alkaline phosphatase (ALP), bone Gla protein (BGP) and urinary N-telopeptide cross-links of collagen normalized for creatinine (NTX/CRT) were also determined. Serum isoflavone concentration was analyzed by high performance liquid chromatography. The 2-year dried beancurd supplementation generated a significant increase in lumbar spine BMD. An obvious decrease was found in urinary NTX/CRT, and a significant increase was detected in serum isoflavone concentration. The dried beancurd supplementation had no effect on changes of right proximal femur BMD and concentrations of serum ALP and BGP. Daily supplementation of dried beancurd could increase BMD of lumbar spine, but does not slow bone loss at right proximal femur in postmenopausal Chinese women.

Serum Isoflavone Concentrations and Equol-Producing Intestinal Flora in Prostate Cancer in Japanese-American in Hawaii

Studies have reported that soy isoflavones and the ability to produce equol may play a role in the prevention of prostate cancer (PCa). To further investigate this relationship, we evaluated Japanese-Americans (JA) and Caucasians (CA) in Hawaii with and without PCa, with regards to dietary soy intake, serum isoflavone levels, and the presence of equol-producing Slackia sp. in the intestine. The serum levels of isoflavone were determined in 65 JA (34 PCa, 31 controls) and 68 CA (34 PCa, 34 controls). All completed a lifetime dietary soy consumption survey. The serum levels of genistein and o-DMA were significantly higher in JA (p = 0.04). Daidzein and isoflavone levels trended higher in JA, but no differences were noted in dihydrodaidzein (DHD) and equol levels. There were no differences in serum isoflavone levels between PCa patients and controls for both JA and CA. Only 8.6% stool samples were positive for equol-producing Slackia sp., a rate much lower than seen in Japan. JA reported a higher intake of soy than CA. The high soy consumption and isoflavone levels in JA may be related to the lower incidence of PCa relative to CA in Hawaii. The near absence of equol producers in Hawaii JA may contribute to their higher incidence of PCa compared to Japan Japanese. These results suggest that both soy isoflavone levels and equol production may be inversely associated with PCa risk.

Effects of standardized phytoestrogen on Taiwanese menopausal women

ObjectiveTo investigate the effects of standardized soy extract on climacteric symptoms, lipid profiles, bone markers, and serum isoflavone concentration in healthy Taiwanese postmenopausal women. Materials and MethodsA multicenter, open-labeled, randomized, prospective, comparative study design was used. A total of 130 outpatients who had undergone natural menopause were randomly administered either 70 mg or 35 mg soy extract daily for 24 weeks. ResultsThe evidence suggests that the soy extract treatment that was administered to both groups for 1 month could help reduce climacteric scores (reductions of 19.66% [p<0.01] and 18.85% [p<0.01] in the 35 mg and 70 mg groups compared with baseline, respectively), and the efficacy was more potent after 6 months of treatment. Soy isoflavone significantly reduced the total cholesterol (reductions of 4.50% [p<0.01] and 3.06% [p<0.05] in the 35 mg and 70 mg groups, respectively) and low density lipoprotein cholesterol levels (reductions of 4.67% [p<0.05] and 5.09% [p<0.05] in the 35 mg and 70 mg groups, respectively) in patients with total cholesterol > 200 mg/dL after 6 months of treatment. In patients with high bone turnover (urinary deoxypyridinoline/creatinine > 7.4nM/mM), soy extract treatment reduced the deoxypyridinoline /creatinine level by 10.53% (p<0.05) and 11.58% (p<0.05) in the 35 mg and 70 mg groups, respectively. Serum levels of isoflavone increased in both groups after 6 months of treatment. ConclusionSoy extract is highly efficacious at relieving menopausal symptoms and demonstrates a positive effect on the cardiovascular system and skeleton.

High serum isoflavone concentrations are associated with the risk of precocious puberty in Korean girls

The gradual decrease in the age of onset of puberty raises concerns about the contribution of phytoestrogen intake on sexual maturation. However, no data are available on the association between serum isoflavone (genistein, daidzein) concentration and central precocious puberty (CPP). The aim of the study was to test the association between serum isoflavone concentrations and the risk of CPP in Korean girls. A case-control study was conducted at Inje University Hospital in Korea. One-hundred and eight girls with CPP (aged 8·6 ± 0·8 year) and 91 age-matched controls (aged 8·5 ± 0·8 year) were examined. Serum concentrations of daidzein (P = 0·0202), genistein (P = 0·0021) and total isoflavones (P = 0·0009) were higher in children with CPP than in normal children. When the children were categorized into three groups according to total serum isoflavone as follows: <30, 30-70 and ≥70 nmol/l, serum concentrations of daidzein, genistein and total isoflavones significantly increased across three categories of serum isoflavone (P < 0·0001). The prevalence of CPP was significantly higher in children with serum isoflavone level of ≥30 nmol/l than those with serum level of <30 nmol/l (P = 0·0008). The adjusted OR for precocious puberty increased significantly across a range of total serum isoflavone (OR = 4·39; 95% CI: 1·83-10·51 vs OR = 5·22; 95% CI: 2·07-13·20; P = 0·001). These results suggest that elevated serum isoflavones may be associated with the risk of CPP in Korean girls.

Early Life Exposure to Isoflavones Adversely Affects Reproductive Health in First but Not Second Generation Female CD-1 Mice

AbstractSoy-based infant formula (SBIF) can be a substantial source of soy isoflavones during early life. Because soy isoflavones have the capacity to mimic endogenous estrogen and thereby exert hormone-like effects, there is concern regarding reproductive health. The objectives were to determine if neonatal exposure to soy isoflavones altered reproductive health in females and, if so, whether such effects are transferred to subsequent generations. CD-1 mice were bred and F1 mouse offspring were cross-fostered at birth and randomized to 1 of 4 treatments: 7 mg soy isoflavoneskg body weight–1 d–1or corn oil from postnatal d (PND) 1 to 10 or from PND 1 to 21 (n= 8–13 females/group). Mice were subsequently bred to control males on PND 56 to obtain F2 females (n= 10–15/group). F1 mice that received isoflavones had ~15% greater body weight during wk 48 and markedly reduced fertility with a 55–60% success rate. Reduced fertility was associated with abnormal estrus cycles, fewer corpora lutea in ovaries, and increased incidence of hyperplasia and atypia in the uteri. Offspring (F2 mice) of isoflavone-treated F1 mice had ~15% higher body weight by wk 8 through 16 of age than controls and fertility was normal. In summary, early exposure to soy isoflavones resulting in serum isoflavone concentrations similar to human infants fed SBIF reduced fertility in F1 but not F2 mice and increased body weight in both generations of female offspring. Extrapolation of these findings to the human scenario are complex but can provide guidance for more fully understanding the implications for infants consuming SBIF.

Effects of a High Dose, Aglycone-Rich Soy Extract on Prostate-Specific Antigen and Serum Isoflavone Concentrations in Men With Localized Prostate Cancer

The efficacy and safety of consuming high-dose isoflavone supplements for prostate cancer is not clear. A double-blind, placebo controlled, randomized trial was conducted in 53 men with prostate cancer enrolled in an active surveillance program. The treatment group consumed a supplement containing 450 mg genistein, 300 mg daidzein, and other isoflavones daily for 6 mo. Prostate-specific antigen (PSA) was measured in both groups at baseline, 3 mo, and 6 mo, and serum concentrations of genistein, daidzein, and equol were assessed at baseline and 6 mo in the treatment group. Following the completion of the 6-mo double-blind study, men were enrolled in a 6-mo open label trial with the same isoflavone-rich supplement, and PSA was measured at 3 and 6 mo. PSA concentrations did not change in either group after 6 mo or after 12 mo when the open-label study was included. The 6 mo serum concentrations of genistein and daidzein (39.85 and 45.59 μmol/l, respectively) were significantly greater than baseline values and substantially higher than levels previously reported in other studies. Equol levels did not change. Although high amounts of aglycone isoflavones may result in significantly elevated serum concentrations of genistein and daidzein, these dietary supplements alone did not lower PSA levels in men with low-volume prostate cancer.

Brief Telephone Intervention Increases Soy Intake in Peri- and Postmenopausal US Women: The Herbal Alternatives Trial (HALT)

Objective Effective dietary intervention strategies that can be widely disseminated and have the potential for sustainable dietary modifications are needed. The purpose of this study was to describe and evaluate the effectiveness of a telephone-based soy intervention. Design A randomized controlled trial comparing self-reported intake and serum measures of soy during a 1-year dietary soy (Soy) to fruit and vegetable (Placebo) intervention conducted in two of five arms from the Herbal Alternatives Trial between May 2001 and September 2004. Subjects/setting One hundred sixty-three peri- and postmenopausal women (mean age=52 years) consuming self-selected diets in the Pacific Northwest, United States. Intervention Five telephone contacts with a registered dietitian during a 12-month intervention with the goal to increase soy food consumption to two servings daily. Main outcome measures Change from baseline in self-reported soy servings and serum isoflavone (daidzein and genistein) concentrations were estimated using analysis of variance and generalized estimating equations. Proportions of participants achieving the intervention goal were compared using χ 2 tests. Results Ninety-four percent (n=74) of participants in the Soy arm and 89% (n=75) in the Placebo arm completed the trial, and slightly more than one third (n=27) received five phone contacts. Mean (±standard deviation) intakes of soy were similar for the Soy and Placebo arms at baseline (0.6±1.0 vs 0.4±0.8 servings/day; P>0.05). At 12-month follow-up visit, mean±standard deviation servings of soy per day were 1.6±1.4 for the Soy intervention compared to 0.5±0.9 within the Placebo arm ( P<0.001). There were concomitant increases in serum isoflavones at 3 and 6 months from baseline in the Soy arm only, with approximately twofold increases in both daidzein (mean=66.4 nmol/L, 95% confidence interval [CI]: 39.0 to 93.9 [mean 16.9 ng/mL, 95% CI: 9.9 to 23.8]) and genistein (mean=100.4 nmol/L, 95% CI: 60.9 to 139.9 [mean 27.1 ng/mL, 95% CI: 16.5 to 37.8]) concentrations. Mean weight changed by <1 kg during the 12-month period in each group and physical activity remained stable, suggesting that participants incorporated soy foods into their diet by substituting for nonsoy foods rather than adding them to their diet. Conclusions A brief telephone-based intervention with a focused message delivered by a registered dietitian is a feasible approach for encouraging targeted dietary changes, such as an increase in soy intake among peri- and postmenopausal women.

Dietary Equol and Bone Metabolism in Postmenopausal Japanese Women and Osteoporotic Mice

Equol binds to the estrogen receptor with greater affinity than its precursor, daidzein, an isoflavone found in soybeans. Inter-individual differences in the ability to produce equol may lead to differential effects of isoflavone intervention on human health. Here, we review previously published work from our laboratory on equol producer status and bone health in humans and in a mouse model of osteoporosis. We performed a 1-y, double-blind, randomized trial to compare the effects of isoflavone (75 mg of isoflavone conjugates/d; equivalent to 47 mg/d of the aglycone form) with those of placebo on bone mineral density (BMD), fat mass, and serum isoflavone concentrations in 54 early postmenopausal Japanese women classified by their equol-producer phenotype. Isoflavone intervention increased the serum equol concentration in equol producers but not in nonproducers (P < 0.04). The annualized changes in BMD in the total hip and intertrochanteric regions in the isoflavone-treated equol producers (−0.46 and −0.04%, respectively) were less than in the nonproducers (−2.28 and −2.61%, respectively). The annualized change in fat mass was lower in the equol producers compared with the nonproducers in the isoflavone group. The annualized changes in BMD and fat mass did not differ between the equol producers and nonproducers in the placebo group. Equol also inhibited bone loss and fat accumulation in estrogen-deficient osteoporotic mice. Our data suggest that prevention of bone loss and fat accumulation in early postmenopausal women by isoflavones may depend on an individual’s equol-producing capacity. J. Nutr. 140: 1373S–1376S, 2010.

The relationship between changes in serum isoflavone concentrations and changes in body fat distribution with soy isoflavone supplementation in postmenopausal women

The relationship between changes in serum isoflavone concentrations and changes in body fat distribution with soy isoflavone supplementation in postmenopausal women

Effects of soy vs. casein protein on body weight and glycemic control in female monkeys and their offspring

Nutritional interventions are important for reducing obesity and related conditions. Soy is a good source of protein and also contains isoflavones that may affect plasma lipids, body weight, and insulin action. Described here are data from a monkey breeding colony in which monkeys were initially fed a standard chow diet that is low fat with protein derived from soy. Monkeys were then randomized to a defined diet with a fat content similar to the typical American diet (TAD) containing either protein derived from soy (TAD soy) or casein-lactalbumin (TAD casein). The colony was followed for over two years to assess body weight, and carbohydrate and lipid measures in adult females (n=19) and their offspring (n=25). Serum isoflavone concentrations were higher with TAD soy than TAD casein, but not as high as when monkey chow was fed. Offspring consuming TAD soy had higher serum isoflavone concentrations than adults consuming TAD soy. Female monkeys consuming TAD soy had better glycemic control, as determined by fructosamine concentrations, but no differences in lipids or body weight compared with those consuming diets with TAD casein. Offspring born to dams consuming TAD soy had similar body weights at birth but over a two-year period weighed significantly less, had significantly lower triglyceride concentrations, and like adult females, had significantly lower fructosamine concentrations compared to TAD casein. Glucose tolerance tests in adult females were not significantly different with diet, but offspring eating TAD soy had increased glucose disappearance with overall lower glucose and insulin responses to the glucose challenge compared with TAD casein. Potential reasons for the additional benefits of TAD soy observed in offspring but not in adults may be related to higher serum isoflavone concentrations in offspring, presence of the diet differences throughout more of their lifespan (including gestation), or different tissue susceptibilities in younger animals.

Supplementary health benefits of soy aglycons of isoflavone by improvement of serum biochemical attributes, enhancement of liver antioxidative capacities and protection of vaginal epithelium of ovariectomized rats

BackgroundIn the literature, supplement of soy aglycons of isoflavone as estrogen agonists in improvement of serum biochemical attributes, liver antioxidative capacities and vaginal epithelium protection has been meagerly investigated. In this study, ovariectomized (OVX) rats were used as an animal model to simulate post-menopausal status. Supplementary health benefits of soy aglycons of isoflavone (SAI) on improvement of growth and serum biochemical attributes, enhancement of liver antioxidation-related capacities and protection of vaginal epithelium of the OVX rats were assessed.MethodsAs an in vivo study, 30 OVX Sprague-Dawley rats were distributed into OVX (positive control), OVX/LSAI (low SAI group – supplemented with 0.0135% SAI being equivalent to 80 mg per day for a 60 Kg-human), and OVX/HSAI (high SAI group – supplemented with 0.027% SAI) and 10 rats with sham operation as negative control fed with basal diet.ResultsThe average daily gain (ADG), feed intake and feed/gain ratio were higher for the OVX groups than the sham group (P < 0.05). Serum isoflavone concentrations of the OVX rats were increased by SAI supplementation. In comparison, significantly lower serum cholesterol and LDL (low-density lipoprotein) levels, and higher HDL (high-density lipoprotein) levels were detected for the rats of OVX/HSAI group (P < 0.05). SAI supplementation also increased iron chelating ability and decreased values of TBARS (thiobarbituric acid-reactive substance) (P < 0.05) of liver extracts. Liver catalase activity and total antioxidative activity (trolox equivalency) were enhanced by HSAI supplementation (P < 0.05). Decrease of vagina epithelial cellular linings of the OVX rats were noticeably improved by dietary supplementation with SAI.ConclusionDiets supplemented with soy aglycons of isoflavone have conferred health benefits to the OVX rats, in comparison to the sham rats fed with basal diet, by detection of higher serum isoflavone concentrations, significantly lower contents of serum cholesterol and LDL, and higher contents of serum HDL, increased iron chelating ability, lower contents of TBARS (thiobarbituric acid-reactive substance) and enhanced catalase and total antioxidative (as trolox equivalency) activities of the liver extracts, and protection of the epithelial cellular linings of vagina in the former rather than in the latter. This evidences that estrogen-agonist chemoprevention of menopausal-related cardiovascular diseases, decreased liver antioxidative capacities and epithelial degeneration of vagina could be achieved by dietary supplementation with soy aglycons of isoflavone.

Pasta Naturally Enriched with Isoflavone Aglycons from Soy Germ Reduces Serum Lipids and Improves Markers of Cardiovascular Risk

Most studies of soy and cholesterol have tested foods made from purified soy proteins containing mainly isoflavone glycosides. Fermented soy foods have mainly isoflavone aglycons and account for a high proportion of the soy protein source in Asia, where there is an inverse relationship between soy intake and serum cholesterol. The aim of this study was to compare a novel soy germ pasta, naturally enriched in isoflavone aglycons as a result of the manufacturing process, with conventional pasta for effects on serum lipids and other cardiovascular risk markers. In this randomized, controlled, parallel study design of 62 adults with hypercholesterolemia who consumed a Step II diet that included one 80-g serving/d of pasta, we measured serum lipids, high sensitivity C-reactive protein (hsCRP), urinary isoprostanes, and brachial artery flow-mediated vasodilatation at baseline and after 4 and 8 wk. The pasta delivered 33 mg of isoflavones and negligible soy protein and led to a serum isoflavone concentration of 222 ± 21 nmol/L; 69% of subjects were equol producers. Soy germ pasta reduced serum total and LDL cholesterol by 0.47 ± 0.13 mmol/L (P = 0.001) and 0.36 ± 0.10 mmol/L (P = 0.002) more than conventional pasta, representing reductions from baseline of 7.3% (P = 0.001) and 8.6% (P = 0.002), respectively. Arterial stiffness (P = 0.003) and hsCRP (P = 0.03) decreased and improvements in all the above risk markers were greatest in equol producers. All measures returned to baseline when patients were switched to conventional pasta. In conclusion, pasta naturally enriched with isoflavone aglycons and lacking soy protein had a significant hypocholesterolemic effect beyond a Step II diet and improved other cardiovascular risk markers.

Possible role of equol status in the effects of isoflavone on bone and fat mass in postmenopausal Japanese women

Equol is more biologically active than its precursor daidzein, which is the principal isoflavone found in soybean. There are interindividual differences in the ability to produce equol; these may lead to differences in the effects of isoflavone intervention on human health. This study aimed to investigate whether the effects of soy isoflavones on bone and fat mass are related to an individual's equol status. We performed a 1-year double-blind, randomized trial to compare the effects of isoflavone (75 mg of isoflavone conjugates/day) with those of placebo on bone mineral density, fat mass, and serum isoflavone concentrations in early postmenopausal Japanese women who were classified based on their equol-producer phenotype. After 1 year, the isoflavone intervention significantly increased the serum equol concentration in the equol producers but not in the nonproducers. In the isoflavone group, the annualized changes in the bone mineral density of the total hip and intertrochanteric regions were -0.46% and -0.04%, respectively, in the equol producers and -2.28% and -2.61%, respectively, in the nonproducers; these values were significantly different (P<0.05 for both the regions). Significant differences were observed between the equol producers and nonproducers in the isoflavone group with regard to the annualized changes in the fat mass. No significant difference in the annualized changes in bone mineral density and fat mass was observed between the equol producers and nonproducers in the placebo group. Our data suggest that the preventive effects of isoflavones on bone loss and fat accumulation in early postmenopausal women depend on an individual's equol-producing capacity.

Bioavailability of Isoflavones after Ingestion of Soy Beverages in Healthy Adults

AbstractIt is unknown whether the bioavailability of isoflavones is affected by the concomitant ingestion of glucosides or aglycones. This study was designed to investigate the effects of soymilk-based beverages containing different types of isoflavones on their absorption, excretion, and metabolism. Twelve healthy volunteers consumed 3 kinds of soymilk: untreated soymilk, β-glucosidase–treated soymilk, and fermented soymilk. Blood samples were collected after 0, 1, 2, 3, 4, 5, 6, 7, 8, and 24 h. Urine samples were collected from 0 to 48 h. Concentrations of isoflavones and daidzein metabolites in serum and urine were measured by liquid chromatography-mass spectrometry. After the ingestion of soymilk, the total concentration of isoflavones in serum rose slowly and reached a maximum of 0.94 ± 0.39 μmol/L at 6.0 ± 1.2 h. However, β-glucosidase–treated soymilk and fermented soymilk increased the serum isoflavone concentration significantly more quickly with maximum concentrations at 1.0 h of 1.75 ± 0.33 μmol/L and 2.05 ± 0.32 μmol/L, respectively. The urinary excretion of isoflavones after ingesting of these aglycone-enriched preparations was significantly greater than after consumption of untreated soymilk up to 8 h after injection, but not thereafter. The total and individual concentrations of isoflavones in serum and urine did not differ when subjects consumed the 2 aglycone-enriched soymilks. However, in equol producers (n = 5), the ingestion of ESM tended to increase urinary excretion of equol compared with the consumption of FSM (P = 0.08). These results demonstrated that the isoflavone aglycones of soymilk were absorbed faster and in greater amounts than their glucosides in healthy adults and that the metabolism of isoflavones might be affected by the type of soymilk consumed.

Effects of soy on the mammary glands of premenopausal female monkeys

To evaluate the interactive effects of dietary soy and menstrual cycle phase on breast proliferation, apoptosis, and sex steroid receptor expression in premenopausal female cynomolgus monkeys. Animals were randomized to receive diets with either casein lactalbumin or soy as the protein source for 12 months. Paired follicular and luteal mammary gland biopsies were taken before and after treatment and evaluated for epithelial proliferation and area, apoptosis, and sex steroid receptor expression. Academic research environment. Fifty-two adult female cynomolgus monkeys (Macaca fascicularis). Soy protein with the human equivalent of 129 mg/d of isoflavones. Breast proliferation and epithelial area. Follicular and luteal assessments were taken on cycle day (+/- SE) 5.3 +/- 0.1 and 22.0 +/- 0.1, respectively. Serum E2, serum P, breast proliferation, and vaginal maturation were significantly higher in the luteal vs. follicular phase. Soy treatment resulted in significantly higher serum isoflavone concentrations compared with the casein lactalbumin group but did not significantly affect breast proliferation, epithelial area, apoptosis, or progesterone receptor expression; uterine size; or vaginal maturation in either the follicular or luteal phase. Results indicate that dietary levels of soy intake have no detectable hormonal effects on the premenopausal breast.