The effect of soy consumption on the urinary 2:16-hydroxyestrone ratio in postmenopausal women depends on equol production status but is not influenced by probiotic consumption

Effect of Probiotics in Breast Cancer: A Systematic Review and Meta-Analysis

Probiotics may have the potential to protect against breast cancer, partly through systemic immunomodulatory action and active impact upon intestinal microbiota. Given a few clinical studies on their curative role, we conducted a systematic review of the potential effects of probiotics in breast cancer patients and survivors of breast cancer, aiming to support further clinical studies. A literature search was performed using PubMed, Embase, and the CENTRAL databases from inception through to March 2022. A total of eight randomized clinical trials were identified from thirteen articles published between 2004 and 2022. We evaluated quality-of-life measures, observed bacterial species and diversity indices, probiotic-related metabolites, inflammatory biomarkers, and other responses in breast cancer patients and survivors. Results were synthesized qualitatively and quantitatively using random-effects meta-analysis. Different probiotics supplements utilized included Lactobacillus species alone (Lacto), with or without estriol; probiotic combinations of Lactobacillus with Bifidobacterium (ProLB), with or without prebiotic fructooligosaccharides (FOS); ProLB plus Streptococcus and FOS (ProLBS + FOS); and ProLB plus Enterococcus (ProLBE). We found that use of ProLBS with FOS in breast cancer patients and use of ProLBE in survivors of breast cancer show potential benefits in countering obesity and dyslipidemia. ProLBS with FOS use decreases pro-inflammatory TNF-α in breast cancer survivors and improves quality of life in those with breast-cancer-associated lymphedema. Supplementing probiotics capsules (10⁹ CFU) with a prebiotic and using an intake duration of 10 weeks could provide a better approach than probiotics alone.

Gut Microbiota-Assisted Synthesis, Cellular Interactions and Synergistic Perspectives of Equol as a Potent Anticancer Isoflavone

It is well known that, historically, plants have been an important resource of anticancer agents, providing several clinically approved drugs. Numerous preclinical studies have shown a strong anticancer potential of structurally different phytochemicals, including polyphenolic constituents of plants, flavonoids. In this review article, suppressing effects of equol in different carcinogenesis models are unraveled, highlighting the mechanisms involved in these anticancer activities. Among flavonoids, daidzein is a well-known isoflavone occurring in soybeans and soy products. In a certain part of population, this soy isoflavone is decomposed to equol under the action of gut microflora. Somewhat surprisingly, this degradation product has been shown to be more bioactive than its precursor daidzein, revealing a strong and multifaceted anticancer potential. In this way, it is important to bear in mind that the metabolic conversion of plant flavonoids might lead to products that are even more efficient than the parent compounds themselves, definitely deserving further studies.

Managing Menopausal Symptoms in Young Women With Breast Cancer: When Medicine Is Not All. The Take Care Project

In the last decade, endocrine therapy strategies in perimenopausal women with hormone-responsive early breast cancer (BC) have changed and now ovarian function suppression (OFS) is recommended for the majority of patients. Side effects of OFS mimic menopausal symptoms, including hot flushes, sweats, weight gain, and sexual dysfunction, which may negatively impact quality of life (QoL). Aims of the Take Care Project are the education of physicians and patients to have all the information (medical and nonmedical) they need to manage menopausal symptoms by distributing educational materials useful to face menopause. Four different areas have been identified by surveys conducted among physicians and young patients: for each area, interventions and tools have been elaborated by a doctor and nonphysician professionals of these identified areas, to offer the widest information available. Clinical and practical suggestions have been provided. Based on the evidence given, we strongly suggest setting up a multidisciplinary team for the treatment planning of young patients with BC, which could help patients to face and manage their new menopause condition. The reduction of side effects and the improvement in QoL should be the best ally to treat young patients with BC.

Prebiotics enhance the biotransformation and bioavailability of ginsenosides in rats by modulating gut microbiota

Background

Gut microbiota mainly function in the biotransformation of primary ginsenosides into bioactive metabolites. Herein, we investigated the effects of three prebiotic fibers by targeting gut microbiota on the metabolism of ginsenoside Rb1 in vivo.

Methods

Sprague Dawley rats were administered with ginsenoside Rb1 after a two-week prebiotic intervention of fructooligosaccharide, galactooligosaccharide, and fibersol-2, respectively. Pharmacokinetic analysis of ginsenoside Rb1 and its metabolites was performed, whilst the microbial composition and metabolic function of gut microbiota were examined by 16S rRNA gene amplicon and metagenomic shotgun sequencing.

Results

The results showed that peak plasma concentration and area under concentration time curve of ginsenoside Rb1 and its intermediate metabolites, ginsenoside Rd, F2, and compound K (CK), in the prebiotic intervention groups were increased at various degrees compared with those in the control group. Gut microbiota dramatically responded to the prebiotic treatment at both taxonomical and functional levels. The abundance of Prevotella, which possesses potential function to hydrolyze ginsenoside Rb1 into CK, was significantly elevated in the three prebiotic groups (P < 0.05). The gut metagenomic analysis also revealed the functional gene enrichment for terpenoid/polyketide metabolism, glycolysis, gluconeogenesis, propanoate metabolism, etc.

Conclusion

These findings imply that prebiotics may selectively promote the proliferation of certain bacterial stains with glycoside hydrolysis capacity, thereby, subsequently improving the biotransformation and bioavailability of primary ginsenosides in vivo.

Inter-relationship between diet, lifestyle habits, gut microflora, and the equol-producer phenotype: baseline findings from a placebo-controlled intervention trial

OBJECTIVE

Equol is an active metabolite of isoflavones produced by gut microbiota. It is beneficial to health; however, equol-producing ability varies greatly among individuals. These variations depend on the host's gut microbiota and lifestyle habits including diet. We investigated the relationship between the gut microbiota, lifestyle habits including diet, and equol-producing ability in postmenopausal Japanese women.

METHODS

We studied 58 postmenopausal Japanese women aged 48 to 69 years who visited the Sendai Medical Center in January, 2018. Self-administered questionnaires assessed their recent and remote food intake histories and lifestyle habits. Fecal microbiome analysis was performed using a next-generation sequencer. Urinary equol was measured using an immunochromatographic strip test. Women with urinary equol concentration >1.0 μM were defined as equol producers.

RESULTS

Equol-producing bacteria were identified in 97% (56) of women; however, only 13 (22%) were equol producers. Equol producers showed significantly higher microflora diversity (P = 0.002), and significantly different recent and remote food intake patterns compared with equol nonproducers. Higher consumption of foods such as meat, fish, soy, vegetables, and Japanese snacks positively affected microbial diversity and equol production, whereas a high intake of Ramen and smoking showed negative effects.

CONCLUSION

Equol production might not depend on the quantity, but on the quality of equol-producing bacteria. High microbial diversity might enhance equol production. Increasing microbial diversity through healthy lifestyle habits and habitual consumption of a wide variety of foods might be useful to maintain a healthy gut environment for equol production.

Equol: A Bacterial Metabolite from The Daidzein Isoflavone and Its Presumed Beneficial Health Effects

Epidemiological data suggest that regular intake of isoflavones from soy reduces the incidence of estrogen-dependent and aging-associated disorders, such as menopause symptoms in women, osteoporosis, cardiovascular diseases and cancer. Equol, produced from daidzein, is the isoflavone-derived metabolite with the greatest estrogenic and antioxidant activity. Consequently, equol has been endorsed as having many beneficial effects on human health. The conversion of daidzein into equol takes place in the intestine via the action of reductase enzymes belonging to incompletely characterized members of the gut microbiota. While all animal species analyzed so far produce equol, only between one third and one half of human subjects (depending on the community) are able to do so, ostensibly those that harbor equol-producing microbes. Conceivably, these subjects might be the only ones who can fully benefit from soy or isoflavone consumption. This review summarizes current knowledge on the microorganisms involved in, the genetic background to, and the biochemical pathways of, equol biosynthesis. It also outlines the results of recent clinical trials and meta-analyses on the effects of equol on different areas of human health and discusses briefly its presumptive mode of action.

A Nutraceutical Approach to Menopausal Complaints

The menopausal transition, or perimenopause, is characterized by menstrual irregularities, vasomotor symptoms, sleep disturbances, mood symptoms, and urogenital tract atrophy. These changes can also affect the quality of life and one’s self-esteem. Hormone replacement therapy (HRT) is considered the best option to achieve therapeutic relief of different menopausal symptoms but is usually restricted to moderate or severe symptoms. Moreover, many women refuse HRT for a variety of reasons concerning the fear of cancer and other adverse effects. According to these considerations, new topics are emerging: Dissatisfaction with drug costs and conventional healthcare, desire for personalized medicines, and the public perception that “natural is good”. In this context, nonhormonal therapies are mostly evolving, and it is not unusual that women often request a “natural” approach for their symptoms. The aim of this study is to investigate nonhormonal therapies that have been identified to reduce the menopausal symptoms.

Adding Agnus Castus and Magnolia to Soy Isoflavones Relieves Sleep Disturbances Besides Postmenopausal Vasomotor Symptoms-Long Term Safety and Effectiveness

The effectiveness for vasomotor symptoms and sleep disorders plus the long-term safety of a nutraceutical combination of agnus-castus and magnolia extracts combined with soy isoflavones (SI) and lactobacilli were assessed in postmenopausal women. A controlled study was carried out in menopausal women comparing this nutraceutical combination (ESP group) with a formulation containing isoflavones alone (C group) at the dosage recommended. The Kuppermann index, The Pittsburgh Sleep Quality Index (PSQI), and Short Form 36 (SF-36) were determined at baseline, three, six and 12 months. Endometrial thickness, mammary density and liver function were evaluated at baseline and after 12 months. One hundred and eighty women were enrolled in the study (100 in the ESP group and 80 in the C group). At the end of the treatment, mammary density, endometrial thickness, and hepatic function did not show substantial differences between groups. The Kuppermann index and particularly the tendency for hot flashes progressively and significantly decreased in frequency and severity during ESP versus C treatment. At the same time, a significant increase in sleep quality and psychophysical wellness parameters was observed in the ESP versus C groups. No adverse events were observed. Agnus-castus and magnolia, combined with SI + lactobacilli, can effectively and safely be used in symptomatic postmenopausal women, mainly when quality of sleep is the most disturbing complaint. The endometrium, mammary glands and liver function were unaffected after 12 months of treatment.

Absorption, distribution, metabolism, and excretion of isoflavonoids after soy intake

Soy is the major source of dietary exposure to isoflavonoids (IFLs). Accumulating evidence supports a role for soy and IFLs in the protection against many chronic diseases including cancer. After soy intake we found a biphasic IFL appearance pattern in plasma as well as in urine that we suggest to be due to IFL absorption in the small intestine (ca. 10%) during the first 2h after intake and IFL absorption in the large intestine (ca. 90%) 4-6 h after intake. While each IFL disappears from the circulation at different times excellent correlations between urinary and circulating IFL values were discovered and algorithms to convert urinary excretion values into circulating levels were established. We suggest the term 'apparent bioavailability' when using urinary data to describe IFL exposure. The IFL bioavailability was found to be influenced by gut bacteria, oral antibiotic treatment (OABX), and an individual's age and health status. While daidzein (DE) and genistein start to be absorbed minutes after intake, equol (EQ) appears in plasma only after a minimum of 8h following soy intake owing to the required transit time of DE to the colon where the conversion of DE to EQ takes place by intestinal microbiota. We have also shown that the apparent IFL bioavailability is higher in children than adults, higher in healthy versus non-healthy individuals, and decreased in children but increased in adults during OABX. Finally, we propose to use a urinary EQ/DE ratio of 0.018 with a DE threshold to identify EQ producers. With this cutoff definition we observed that EQ production is inconsistent over time in 5-30% of both premenopausal and postmenopausal women.

Gut microbes, diet, and cancer

An expanding body of evidence supports a role for gut microbes in the etiology of cancer. Previously, the focus was on identifying individual bacterial species that directly initiate or promote gastrointestinal malignancies; however, the capacity of gut microbes to influence systemic inflammation and other downstream pathways suggests that the gut microbial community may also affect risk of cancer in tissues outside of the gastrointestinal tract. Functional contributions of the gut microbiota that may influence cancer susceptibility in the broad sense include (1) harvesting otherwise inaccessible nutrients and/or sources of energy from the diet (i.e., fermentation of dietary fibers and resistant starch); (2) metabolism of xenobiotics, both potentially beneficial or detrimental (i.e., dietary constituents, drugs, carcinogens, etc.); (3) renewal of gut epithelial cells and maintenance of mucosal integrity; and (4) affecting immune system development and activity. Understanding the complex and dynamic interplay between the gut microbiome, host immune system, and dietary exposures may help elucidate mechanisms for carcinogenesis and guide future cancer prevention and treatment strategies.

Soy, red clover, and isoflavones and breast cancer: a systematic review

BACKGROUND

Soy and red clover isoflavones are controversial due to purported estrogenic activity and possible effects on breast cancer. We conducted a systematic review of soy and red clover for efficacy in improving menopausal symptoms in women with breast cancer, and for potential impact on risk of breast cancer incidence or recurrence.

METHODS

We searched MEDLINE, Embase, the Cochrane Library, and AMED from inception to March 2013 for human interventional or observational data pertaining to the safety and efficacy of soy and red clover isoflavones in patients with or at risk of breast cancer.

RESULTS

Of 4179 records, we included a total of 131 articles: 40 RCTs, 11 uncontrolled trials, and 80 observational studies. Five RCTs reported on the efficacy of soy for hot flashes, showing no significant reductions in hot flashes compared to placebo. There is lack of evidence showing harm from use of soy with respect to risk of breast cancer or recurrence, based on long term observational data. Soy intake consistent with that of a traditional Japanese diet (2-3 servings daily, containing 25-50mg isoflavones) may be protective against breast cancer and recurrence. Human trials show that soy does not increase circulating estradiol or affect estrogen-responsive target tissues. Prospective data of soy use in women taking tamoxifen does not indicate increased risk of recurrence. Evidence on red clover is limited, however existing studies suggest that it may not possess breast cancer-promoting effects.

CONCLUSION

Soy consumption may be associated with reduced risk of breast cancer incidence, recurrence, and mortality. Soy does not have estrogenic effects in humans. Soy intake consistent with a traditional Japanese diet appears safe for breast cancer survivors. While there is no clear evidence of harm, better evidence confirming safety is required before use of high dose (≥ 100 mg) isoflavones can be recommended for breast cancer patients.

Potential impact of probiotic consumption on the bioactivity of dietary phytochemicals

Many healthy phytochemicals occur in food in the form of esters, glycoconjugates, or polymers, which are not directly bioavailable. Probiotic lactobacilli and bifidobacteria, which have evolved within the colonic ecosystem where indigestible oligo- and polysaccharides are their sole carbon sources, bear several glycosyl-hydrolases and can contribute to release the aglycones from glycoconjugated phytochemicals. Among the glycosyl-hydrolases, β-glucosidases are the most pertinent, because many phytochemicals are glucoconjugates. β-Glucosidase-positive probiotic bacteria were proved to release the aglycones of isoflavones and lignans in vitro, but studies in vivo are scarce. A positive correlation between probiotic consumption and urinary and/or plasma levels of isoflavone or lignan metabolites was not established. However, the strains used in the trials were not validated for the enzymatic properties or for the ability to hydrolyze lignans or isoflavones. Thus, activation of specific phytochemicals by probiotic bacteria still needs substantial efforts to be proved.

Urinary estrogen metabolites in two soy trials with premenopausal women

Background

Soy consumption may protect against breast cancer through modification of estrogen metabolism.

Objective

We examined the effect of soy foods on urinary estrogens and the 2-hydroxy (OH)/16α-OH estrone (E₁) ratio in 2 dietary interventions with premenopausal women.

Methods

BEAN1 was a 2-year randomized trial and BEAN2 a 13-month randomized crossover study. In both interventions, study participants consumed a high-soy diet with 2 soy food servings/day and a low-soy diet with <3 servings of soy/week. Urine samples were collected at baseline and at the end of the diet periods, analyzed for 9 estrogen metabolites by liquid chromatography mass spectrometry, and adjusted for creatinine levels. For BEAN1, 2 samples for 188 participants and for BEAN2, 3 samples for 79 women were analyzed. We applied mixed-effects regression models with log-transformed values of estrogen metabolites and soy intake as the exposure variable.

Results

In BEAN1, no effect of the high-soy diet on individual estrogen metabolites or hydroxylation pathways was observed. The median 2-OH/16α-OH E₁ ratio decreased non-significantly in the intervention group from 6.2 to 5.2 as compared to 6.8 and 7.2 in the control group (p=0.63). In BEAN2, only 4-OHE₁ was significantly lower after the high-soy diet. Interaction terms of the high-soy diet with equol producer status, ethnicity, and weight status revealed no significant effect modification.

Conclusions

Contrary to our hypothesis and some previous reports, the results from 2 well controlled dietary interventions do not support an effect of a high-soy diet on a panel of urinary estrogen metabolites and the 2-OH/16α-OHE₁ ratio.

Does equol production determine soy endocrine effects?

Isoflavones, a group of phytoestrogens, are selective oestrogen receptor (ER) modulators. They may positively impact endocrine-related conditions but the current evidence is sparse. Equol, a non-steroidal oestrogen, is produced by the metabolism of the isoflavone daidzein by intestinal bacteria. In Western countries, 30-50% of individuals metabolize daidzein into equol and are known as equol producers. Equol production may be the source of benefit from isoflavones in endocrine disease.

Urinary estrogen metabolites during a randomized soy trial

One of the hypothesized protective mechanisms of soy against breast cancer involves changes in estrogen metabolism to 2-hydroxy (OH) and 16α-OH estrogens. The current analysis examined the effect of soy foods on the 2:16α-OH E(1) ratio among premenopausal women during a randomized, crossover intervention study; women were stratified by equol producer status, a characteristic thought to enhance the protective effects of soy isoflavones. The study consisted of a high-soy diet with 2 soy food servings/day and a low-soy diet with <3 servings of soy/wk for 6 mo each; estrogen metabolites were measured in 3 overnight urines (baseline and at the end of the low- and high-soy diet) using gas chromatography mass spectrometry for the 82 women who completed the study. Urinary isoflavonoids were assessed by liquid chromatography mass spectrometry. When applying mixed models, the 2:16α-OH E(1) ratio increased (P = 0.05) because of a nonsignificant decrease in 16α-OH E(1) (P = 0.21) at the end of the high-soy diet. Similar nonsignificant increases in the 2:16α-OH E(1) ratio were observed in equol producers (P = 0.13) and nonproducers (P = 0.23). These findings suggest a beneficial influence of soy foods on estrogen metabolism regardless of equol producer status.

Analysis of urinary estrogens, their oxidized metabolites, and other endogenous steroids by benchtop orbitrap LCMS versus traditional quadrupole GCMS

Estrogens and other endogenous steroids are known risk markers for cancer. Gas chromatography (GC) with mass spectrometry (MS) has traditionally predominated the analysis of estrogens and other endogenous steroids, but liquid chromatography (LC) MS is increasingly favored. Direct comparisons of the two technologies have hitherto not been performed. Steroids were analyzed from 232 urine samples of 78 premenopausal women in a blinded fashion by benchtop orbitrap LCMS and single quadrupole GCMS. Sixteen steroidal estrogens including oxidized metabolites could be analyzed by LCMS. LCMS-GCMS Spearman rank correlations of the major estrogens E(1), E(2), E(3), 16α-OHE(1), and 2-OHE(1) were very high (r = 0.72-0.91), and absolute concentrations also agreed (<5% difference for E(1), E(2), E(3), 16α-OHE(1)). LCMS allowed reinterrogation of the acquired data due to orbitrap technology, which permitted post-analysis quantitation of progesterone, cortisol, and cortisone (LCMS-GCMS Spearman rank correlations = 0.80-0.84; absolute difference, <7%; n = 137). GCMS allows the measurement of a wide range of steroids including non-polar analytes that escape the presented LCMS assay. In contrast, orbitrap-based LCMS can detect more estrogens, is faster, less costly, allows post-data acquisition reinterrogation of certain analytes that had not been targeted a priori, and requires much less urine.

Equol production changes over time in postmenopausal women

Equol (EQ) is produced by intestinal bacteria from the soy isoflavone daidzein (DE) in 30%-60% of the population and is believed to provide benefits from soy intake. A robust EQ status definition is lacking, and it is uncertain whether EQ is formed consistently within an individual and ceases upon oral antibiotic treatment. In a randomized, double-blind, placebo-controlled soy intervention trial with 350 postmenopausal women, DE and EQ were analyzed by liquid chromatography/tandem mass spectrometry at baseline and every 6 months over 2.5 years in overnight urine, spot urine and plasma. Equol production changes and status (remaining an EQ producer or nonproducer or changing towards an EQ producer or nonproducer) were assessed. Equol status was determined most dependably by overnight urine applying as cutoff a ratio of EQ/DE≥0.018 with a DE threshold ≥2 nmol/mg creatinine: the soy and placebo groups had approximately 30% consistent EQ producers during the study, but 14% and 35%, respectively, changed EQ status (mean 1.4-1.7 times), while 27% and 17%, respectively, had antibiotic treatment (P<.01 for inverse association). No significant trend in change of EQ production or status was observed when overnight urine was limited to collections closest to before and after antibiotic treatment. Similarly, antibiotic type or class, duration, dose or time between antibiotic treatment and overnight urine collection showed no consistent influence on EQ production. Equol production can markedly change intraindividually over 2.5 years, and antibiotic treatment impacts it inconsistently. Factors other than antibiotic treatment must be considered as causes for EQ production changes.

Is equol production beneficial to health?

The health benefits associated with soya food consumption have been widely studied, with soya isoflavones and soya protein implicated in the protection of CVD, osteoporosis and cancers such as those of the breast and prostate. Equol (7-hydroxy-3-(4'-hydroxyphenyl)-chroman), a metabolite of the soya isoflavone daidzein, is produced via the formation of the intermediate dihydrodaidzein, by human intestinal bacteria, with only approximately 30-40% of the adult population having the ability to perform this transformation following a soya challenge. Inter-individual variation in conversion of daidzein to equol has been attributed, in part, to differences in the diet and in gut microflora composition, although the specific bacteria responsible for the colonic biotransformation of daidzein to equol are yet to be identified. Equol is a unique compound in that it can exert oestrogenic effects, but is also a potent antagonist of dihydrotestosterone in vivo. Furthermore, in vitro studies suggest that equol is more biologically active than its parent compound, daidzein, with a higher affinity for the oestrogen receptor and a more potent antioxidant activity. Although some observational and intervention studies suggest that the ability to produce equol is associated with reduced risk of breast and prostate cancer, CVD, improved bone health and reduced incidence of hot flushes, others have reported null or adverse effects. Studies to date have been limited and well-designed studies that are sufficiently powered to investigate the relationship between equol production and disease risk are warranted before the clinical relevance of the equol phenotype can be fully elucidated.

Effects of a breast-health herbal formula supplement on estrogen metabolism in pre- and post-menopausal women not taking hormonal contraceptives or supplements: a randomized controlled trial

INTRODUCTION

Both indole-3-carbinol and dietary lignans have beneficial effects on estrogen metabolism and breast cancer risk. There is no published literature on the effects of a combination product. This study was designed to investigate the impact of a combination product on estrogen metabolism. The major trial objective was to determine whether a breast health supplement containing indole-3-carbinol and hydroxymatairesinol lignan would alter estrogen metabolism to favour C-2 hydroxylation and reduce C-16 hydroxylation. Higher concentrations of C-2 metabolites and lower concentrations of C-16 metabolites may reduce breast cancer risk and risk for other hormonally-related cancers.

METHODS

Forty-seven pre-menopausal and forty-nine post-menopausal women were recruited for this study, and were divided by random allocation into treatment and placebo group. The treatment supplement contained HMR lignan, indole-3-carbinol, calcium glucarate, milk thistle, Schisandra chinesis and stinging nettle, and each woman consumed either treatment or placebo for 28 days. At day 0 and day 28, blood samples were analysed for serum enterolactone concentrations, and first morning random urine samples were assessed for estrogen metabolites. Repeated measures ANOVA statistical testing was performed.

RESULTS

In pre-menopausal women, treatment supplementation resulted in a significant increase (P < 0.05) in urinary 2-OHE concentrations and in the 2:16α-OHE ratio. In post-menopausal women, treatment supplementation resulted in a significant increase in urinary 2-OHE concentrations. In pre- and post-menopausal women combined, treatment supplementation produced a significant increase in urinary 2-OHE concentration and a trend (P = 0.074) toward an increased 2:16α-OHE ratio. There were no significant increases in serum enterolactone concentrations in the treatment or placebo groups.

CONCLUSIONS

Supplementation with a mixture of indole-3-carbinol and HMR lignan in women significantly increased estrogen C-2 hydroxylation. This may constitute a mechanism for the reduction of breast cancer risk as well as risk for other estrogen-related cancers. Further studies with higher numbers of subjects are indicated.

Urinary 2/16 estrogen metabolite ratio levels in healthy women: a review of the literature

This is a summary of the published literature on the urinary 2/16 estrogen metabolite ratio in human populations, and a report the observed range of normal values in healthy women. Original research studies that included the measurement of urinary estrogen metabolites in human subjects were identified through an extensive Medline search; 43 distinct studies were identified, including a total of 6802 healthy women. The range of mean values of the 2/16 ratio measured with the ELISA method varied from 0.98 to 1.74; in studies of pre-menopausal women the range of mean values was 1.5-2.74, in studies of post-menopausal women mean values ranged from 1.15 to 2.25. The heterogeneity across studies was highly significant (p-value Q-test: <0.0001). In multivariable analyses, only race confirmed its role as an independent predictor of 2/16 ratio (F-value: 7.95; p-value: 0.009), after adjustment for age and menopausal status. There appears to be a large body of data on the 2/16 urinary ratio in healthy women. However, summary estimates are difficult to perform due to the high variability of the published study-specific values. The data suggests that race may be a contributor to 2/16 urinary ratio levels.

Guidance for substantiating the evidence for beneficial effects of probiotics: impact of probiotics on digestive system metabolism

Probiotic bacteria have been studied for their potential impact on the metabolism of dietary components in the small intestine lumen including lactose digestion, metabolism of lipids such as cholesterol, and oxalate metabolism. In the large intestine, they contribute to the metabolism of otherwise indigestible dietary carbohydrates (e.g., prebiotics) and have a favorable effect on colonic protein and ammonia metabolism, although their effect on the digestive fate of phytochemicals and xenobiotics is still uncertain. Probiotics also influence metabolism in the host tissues, in particular the gastrointestinal mucosa and the liver. Underlying mechanisms include supply of additional enzymatic activities in the gut lumen and alterations of the composition or metabolic pattern of the gut resident microbiota. For future studies, selection of probiotic strains should include assessment of their metabolic activities, and the outcome of the intervention studies should also take into account the composition of the probiotic matrix and the background diet of the target population. New technologies such as metabolomics hold great promise for assessment of probiotics functionality.

Soy intake is associated with increased 2-hydroxylation and decreased 16alpha-hydroxylation of estrogens in Asian-American women

INTRODUCTION

In Asian and Asian-American women, soy consumption is associated with reduced breast cancer risk, perhaps due to its effects on estrogen production or metabolism. In a sample of Asian-American women, we investigated the associations of usual adult soy intake with the urinary concentrations of 15 estrogens and estrogen metabolites (EM) measured using liquid chromatography-tandem mass spectrometry.

METHODS

Participants included 430 Chinese-American, Japanese-American, and Filipino-American women, ages 20 to 55 years, and living in San Francisco-Oakland (California), Los Angeles (California), or Oahu (Hawaii). They were postmenopausal (n = 167) or premenopausal in luteal phase (n = 263) when 12-hour urine samples were collected. Robust linear regression was used to assess soy tertiles as predictors of log-transformed EM measures. Individual and grouped EM were considered as concentrations (pmol/mg creatinine) and as percentages of total EM (%EM).

RESULTS

Factor analysis confirmed that EM groups defined by metabolic pathways appropriately captured covariation in EM profiles. Total EM concentrations were not significantly associated with soy in premenopausal or postmenopausal women. Among all women, %2-hydroxylated EM and %4-hydroxylation pathway EM were 16% higher (P(trend) = 0.02) and 19% higher (P(trend) = 0.03) in the highest versus lowest soy tertiles, respectively. In contrast, 16% hydroxylated EM were 11% lower (P(trend) < 0.01). Results were consistent across ethnic and menopausal groups and after adjustment for westernization measured by birthplace (Asia or United States).

DISCUSSION

Findings suggest that regular soy intake is associated with increased ratios of 2:16-pathway EM and with higher relative levels of 4-hydroxylated EM. The observed variations in estrogen metabolism might modify breast cancer risk.

The improvement of hypertension by probiotics: effects on cholesterol, diabetes, renin, and phytoestrogens

Probiotics are live organisms that are primarily used to improve gastrointestinal disorders such as diarrhea, irritable bowel syndrome, constipation, lactose intolerance, and to inhibit the excessive proliferation of pathogenic intestinal bacteria. However, recent studies have suggested that probiotics could have beneficial effects beyond gastrointestinal health, as they were found to improve certain metabolic disorders such as hypertension. Hypertension is caused by various factors and the predominant causes include an increase in cholesterol levels, incidence of diabetes, inconsistent modulation of renin and imbalanced sexual hormones. This review discusses the antihypertensive roles of probiotics via the improvement and/or treatment of lipid profiles, modulation of insulin resistance and sensitivity, the modulation of renin levels and also the conversion of bioactive phytoestrogens as an alternative replacement of sexual hormones such as estrogen and progesterone.

Effects of soy protein and isoflavones on circulating hormone concentrations in pre- and post-menopausal women: a systematic review and meta-analysis

BACKGROUND

Hormonal effects of soy and isoflavones have been investigated in numerous trials with equivocal findings. We aimed to systematically assess the effects of soy and isoflavones on circulating estrogen and other hormones in pre- and post-menopausal women.

METHODS

The Cochrane Library, MEDLINE and EMBASE (plus reviews and experts) were searched to December 2007. Inclusion of randomized or residential crossover trials of soy or isoflavones for 4 or more weeks on estrogens, SHBG, FSH, LH, progesterone and thyroid hormones in women was assessed independently in duplicate. Six percent of papers assessed were included. Data concerning participants, interventions, outcomes, potential effect modifiers and trial quality characteristics were extracted independently in duplicate.

RESULTS

Forty-seven studies (11 of pre-, 35 of post- and 1 of perimenopausal women) were included. In premenopausal women, meta-analysis suggested that soy or isoflavone consumption did not affect primary outcomes estradiol, estrone or SHBG concentrations, but significantly reduced secondary outcomes FSH and LH [by ∼20% using standardized mean difference (SMD), P = 0.01 and 0.05, respectively]. Menstrual cycle length was increased by 1.05 days (95% CI 0.13, 1.97, 10 studies). In post-menopausal women, there were no statistically significant effects on estradiol, estrone, SHBG, FSH or LH, although there was a small statistically non-significant increase in total estradiol with soy or isoflavones (∼14%, SMD, P = 0.07, 21 studies).

CONCLUSIONS

Isoflavone-rich soy products decrease FSH and LH in premenopausal women and may increase estradiol in post-menopausal women. The clinical implications of these modest hormonal changes remain to be determined.

Isoflavones and the prevention of breast and prostate cancer: new perspectives opened by nutrigenomics

Epidemiological evidence together with preclinical data from animal and in vitro studies strongly support a correlation between soy isoflavone consumption and protection towards breast and prostate cancers. The biological processes modulated by isoflavones, and especially by genistein, have been extensively studied, yet without leading to a clear understanding of the cellular and molecular mechanisms of action involved. This review discusses the existing gaps in our knowledge and evaluates the potential of the new nutrigenomic approaches to improve the study of the molecular effects of isoflavones. Several issues need to be taken into account for the proper interpretation of the results already published for isoflavones. Too often knowledge on isoflavone bioavailability is not taken into account; supra-physiological doses are frequently used. Characterization of the individual variability as defined by the gut microflora composition and gene polymorphisms may also help to explain the discrepancies observed so far in the clinical studies. Finally, the complex inter-relations existing between tissues and cell types as well as cross-talks between metabolic and signalling pathways have been insufficiently considered. By appraising critically the abundant literature with these considerations in mind, the mechanisms of action that are the more likely to play a role in the preventive effects of isoflavones towards breast and prostate cancers are reviewed. Furthermore, the new perspectives opened by the use of genetic, transcriptomic, proteomic and metabolomic approaches are highlighted.

Past oral contraceptive use and current dietary soy isoflavones influence estrogen metabolism in postmenopausal monkeys (Macaca fascicularis)

Estrogen metabolism may play an important role in mammary carcinogenesis in postmenopausal women. We evaluated the effects of prior oral contraceptive (OC) treatment and current soy isoflavone consumption on endogenous estrogen metabolite concentration and biomarkers of tissue estrogen exposure in a monkey model. One hundred eighty-one female cynomolgus macaques were randomized to receive OC or placebo for 26 months premenopausally, then ovariectomized and randomized to one of three diets for 36 months: an isoflavone-depleted soy protein isolate (Soy-) diet, a diet containing soy protein isolate with a human equivalent of 129 mg isoflavone/d (Soy+), or a Soy- diet supplemented with conjugated equine estrogens (CEE+) at a human equivalent dose of 0.625 mg/d. Reverse-phase high-performance liquid chromatography directly coupled with tandem mass spectrometry was used to measure the concentrations of estrogen species in urine samples. Generally, prior OC treatment was associated with significantly reduced urinary estrogen metabolites (25-55% reduction; P<0.05 for each versus OC-). Animals that consumed isoflavones postmenopausally had increased urinary 2-hydroxyestrone and 16alpha-hydroxyestrone (50% and 56% increases, respectively), but reduced levels of 2-hydroxyestradiol, 2-methoxyestradiol, and 17-epiestriol (92%, 63%, and 66%, respectively), compared with animals fed a Soy- diet. Isoflavones did not have widespread effects on uterine or mammary proliferation biomarkers, whereas prior OC significantly reduced two of three proliferation end points in the endometrium. Premenopausal OCs may have long-term systemic effects on response to estrogen and its metabolism whereas postmenopausal dietary isoflavones may alter endogenous estrogen metabolism in a modest but selective manner.

Effects of prior oral contraceptive use and soy isoflavonoids on estrogen-metabolizing cytochrome P450 enzymes

Estrogen exposure and metabolism may play an important role in the development of estrogen-sensitive cancers in postmenopausal women. In this study we investigated whether past oral contraceptive (OC) administration or current dietary isoflavonoids (IF) affected expression and/or activity of steroid hormone-metabolizing cytochrome P450 (CYP) enzymes using complementary primate and cell culture models. One-hundred-eighty-one female cynomolgus macaques were randomized to receive OC or nothing for 26 months premenopausally, then ovariectomized and randomized to one of three diets for 36 months: an IF-depleted soy protein isolate (Soy-) diet, a Soy diet with IF (Soy+), or a Soy- diet supplemented with conjugated equine estrogens (CEE). Prior OC-treatment significantly reduced CYP gene expression in the mammary gland (< or =60% of OC-). Dietary IFs had no effect on CYP expression, while CEE-treatment decreased CYP1A1 and increased CYP3A4 mRNA in a tissue-specific manner. For in vitro studies, we measured effects of the isoflavonoids genistein, daidzein and equol on CYP activity using intact V79 cells stably transfected to express CYP1A1, CYP1B1, or CYP3A4. All three IFs significantly altered CYP activity in a dose-dependent and isoform-specific manner (20-95% inhibition versus controls). These results suggest potential mechanisms for prior OC and dietary IF effects on cancer risk in estrogen-responsive tissues.

The effects of soy isoflavones on obesity

Over the last decades, the prevalence of obesity and related diseases has increased rapidly in the Western world. Obesity is a disorder of energy balance and is associated with hyper-insulinemia, insulin resistance, and abnormalities in lipid metabolism, and it is one of the most important risk factors in the development of Type II diabetes, cardiovascular disease, atherosclerosis, and certain cancers. Because of the lower frequency of these diseases in Asian countries, attention has been turned toward the Asian diet, which consists highly of soy and soy-based products. The health benefits associated with soy consumption have been linked to the content of isoflavones, the main class of the phytoestrogens. As a result of their structural similarities to endogenous estrogens, isoflavones elicit weak estrogenic effects by competing with 17beta-estradiol (E2) for binding to the intranuclear estrogen receptors (ERs) and exert estrogenic or antiestrogenic effects in various tissues. The estrogenic activities of soy isoflavones are thought to play an important role in their health-enhancing properties. Additionally, the isoflavones have been proved to exert non-ER-mediated effects through numerous other pathways. Genistein, daidzein, and glycitein are the principal isoflavones in soy. Genistein is the most thoroughly examined of these, because it is the most prevalent isoflavone in soy and the most active of these compounds, because of its higher binding affinity for the ER. Genistein and daidzein can be obtained in high levels in humans under certain nutritional conditions, and epidemiologic and laboratory data suggest that these compounds could have health benefits in human obesity. This review will focus on the latest results of research on isoflavones and their effect on obesity in cell cultures, rodents, and humans.

Effects of dietary equol administration on the mammary gland in ovariectomized Sprague-Dawley rats

OBJECTIVE

To evaluate the effects of dietary equol, a metabolite of soy-derived daidzein or formononetin present in red clover, on the mammary gland of ovariectomized Sprague-Dawley rats.

DESIGN

Sixty ovariectomized rats were divided into five groups (n = 12) and fed soy-free chow with the addition of equol (50 mg/kg chow and 400 mg/kg chow) or estradiol-3 benzoate (E2B) (4.3 mg/kg chow and 17.3 mg/kg chow). The control group received soy-free chow only. After 3 months animals were killed, blood was collected, and the mammary glands were removed for histological and immunohistochemical evaluation.

RESULTS

Equol and E2B treatment significantly increased serum equol and 17beta-estradiol concentrations, respectively. Serum prolactin in animals treated with high-dose equol was also significantly higher than in the controls. Animals treated with high-dose equol had a significantly higher number of terminal ducts and type II lobules compared with controls. This was also apparent in animals treated with low- and high-dose E2B, but a higher number of type I lobules also was seen. Compared with controls, animals treated with high-dose equol had a significantly higher percentage of proliferating cell nuclear antigen-positive cells in terminal ducts and type II lobules. The percentage of progesterone receptor-positive cells in animals treated with high-dose equol was significantly higher only in type II lobules. In animals treated with low- and high-dose E2B, the percentage of proliferating cell nuclear antigen- and progesterone receptor-positive cells was significantly higher in all the mammary structures. Low-dose equol did not have any effects on the parameters listed above.

CONCLUSIONS

High-dose dietary equol administration to ovariectomized rats exerts clear mammotropic effects.

Daidzein-metabolizing phenotypes in relation to serum hormones and sex hormone binding globulin, and urinary estrogen metabolites in premenopausal women in the United States

OBJECTIVE

Blood and urine concentrations of hormones are implicated in the etiology of some cancers. Small studies have assessed relationships between production of the daidzein metabolites equol and O-desmethylangolensin (ODMA) and hormones, but findings are unclear. We evaluated relationships between daidzein-metabolizing phenotypes and follicular phase concentrations of estrogens, androgens, sex hormone binding globulin (SHBG), and urinary estrogen metabolites in premenopausal women.

METHODS

Two-hundred women collected a first-void urine sample after a 3-day soy challenge, and 191 and 193 provided fasting blood and spot urine samples, respectively, during days 5-9 of their menstrual cycle. Soy challenge urines were analyzed for isoflavones; serum was analyzed for estrogens, androgens, and SHBG; spot urines were analyzed for 2-hydroxyestrone and 16alpha-hydroxyestrone. Data were log-transformed and multiple regression analyses were conducted to assess relationships between daidzein-metabolizing phenotypes and hormones and SHBG. Data from 187 and 189 women were included in analyses of serum and urine hormones, respectively.

RESULTS

55 (27.5%) and 182 (91%) of the 200 women who provided a soy challenge urine sample were equol- and ODMA-producers (>87.5 ng/ml urine), respectively. In unadjusted analyses, equol-producers (n = 52) had lower free testosterone than equol non-producers (n = 137, p = 0.02). In adjusted analyses, there were no differences between producers and non-producers of either daidzein metabolite.

CONCLUSIONS

In the absence of a soy intervention, we found no difference in serum or urine hormone concentrations between producers and non-producers of equol or ODMA.

Equol status modifies the association of soy intake and mammographic density in a sample of postmenopausal women

Only 30% to 50% of people produce the daidzein-metabolite equol after eating soy. We conducted a cross-sectional study of the associations between equol status, intake of soy foods, and mammographic density in a sample of postmenopausal women recruited at a radiology clinic near Buffalo, New York. Participants were 48 to 82 years old, had no history of cancer or breast reduction/augmentation, and no recent use of antibiotics or hormones. Percent density was measured by computer-assisted analysis of digitized images of craniocaudal films. Equol status was assessed using a soy-challenge protocol and usual soy intake by questionnaire. General linear models were used to assess independent and joint effects of equol status and intake of soy on multivariate adjusted percent density (covariates included age, body mass index, parity, age at first birth, and ever use of combined hormone therapy). Of 325 enrolled, 232 (71%) participants completed study assessments and are included in the present analysis. Mean percent density was 34% (+/-18%). Seventy-five (30%) participants were producers of equol. Forty-three (19%) participants reported regularly eating >1 soy food or supplement/wk. There were no significant independent associations of equol status or soy intake with percent density, but the interaction between these factors was significant (P < 0.01). Among equol producers, those with weekly soy intake had lower percent density (30.7% in weekly consumers of soy versus 38.9% in others; P = 0.08); among nonproducers, weekly soy intake was associated with higher percent density (37.5% in weekly soy consumers versus 30.7% in others; P = 0.03). Results suggest that equol producers and nonproducers may experience different effects of dietary soy on breast tissue.

Soy protein isolate increases urinary estrogens and the ratio of 2:16alpha-hydroxyestrone in men at high risk of prostate cancer

Specific estrogen metabolites may initiate and promote hormone-related cancers. In epidemiological studies, significantly lower excretion of urinary estradiol (E2) and lower ratio of urinary 2-hydroxy estrogens to 16alpha-hydroxyestrone (2:16 OH-E1) have been reported in prostate cancer cases compared to controls. Although soy supplementation has been shown to increase the ratio 2:16 OH-E1 in women, no studies to our knowledge have investigated the effects of soy supplementation on estrogen metabolism in men. The objective of this randomized controlled trial was to determine the effects of soy protein isolate consumption on estrogen metabolism in men at high risk for developing advanced prostate cancer. Fifty-eight men supplemented their habitual diets with 1 of 3 protein isolates: 1) isoflavone-rich soy protein isolate (SPI+) (107 mg isoflavones/d); 2) alcohol-washed soy protein isolate (SPI-) (<6 mg isoflavones/d); or 3) milk protein isolate (MPI), each providing 40 g protein/d. At 0, 3, and 6 mo of supplementation, the urinary estrogen metabolite profile was measured by GC-MS. Both soy groups had higher E2 excretion than the MPI group at 3 and 6 mo. After 6 mo of supplementation, the SPI+ group had a significantly higher urinary 2:16 OH-E1 ratio than the MPI group. Increased urinary E2 excretion and 2:16 OH-E1 ratio in men consuming soy protein isolate are consistent with studies in postmenopausal women and suggest that soy consumption may be beneficial in men at high risk of progressing to advanced prostate cancer as a result of effects on endogenous estrogen metabolism.

Probiotics: a critical review of their potential role as antihypertensives, immune modulators, hypocholesterolemics, and perimenopausal treatments

The conventional use of probiotics to modulate gastrointestinal health, such as in improving lactose intolerance, increasing natural resistance to infectious diseases in the gastrointestinal tract, suppressing traveler's diarrhea, and reducing bloating, has been well investigated and documented. Most of the mechanisms reported to date are mainly caused by the suppression of pathogenic bacteria. Currently, the potential applications of probiotics are being expanded beyond alleviating gastrointestinal disorders to include benefits involving antihypertension, immunomodulation, improving serum lipid profiles, and the alleviation of postmenopausal disorders. Although they seem promising, most of these postulated benefits are based on in vitro evaluations, and the lack of in vivo evidence and/or incompatible outcomes between in vitro experiments and in vivo trials has led to inconclusive claims. This present review highlights some of the previous roles of probiotics on gut health and addresses several potential roles currently being investigated.

Metabolism of dietary soy isoflavones to equol by human intestinal microflora--implications for health

Soy isoflavones have received considerable attention. Individuals with isoflavones-rich diets have significantly lower occurrences of cardiovascular disease, osteoporosis, and some cancers. The clinical effectiveness of soy isoflavones may be a function of the ability to biotransform soy isoflavones to the more potent estrogenic metabolite, equol, which may enhance the actions of soy isoflavones, owing to its greater affinity for estrogen receptors, unique antiandrogenic properties, and superior antioxidant activity. However, not all individuals consuming daidzein produce equol. Only approximately one-third to one-half of the population is able to metabolize daidzein to equol. This high variability in equol production is presumably attributable to interindividual differences in the composition of the intestinal microflora, which may play an important role in the mechanisms of action of isoflavones. But, the specific bacterial species in the colon involved in the production of equol are yet to be discovered. Therefore, future researches are aimed at identifying the specific bacterial species and strains that are capable of converting daidzein to equol or increasing equol production.

Urinary phytoestrogen excretion of rats bearing methylnitrosourea-induced mammary carcinoma in response to treatment with 2-methoxyestradiol

The effect of treating mammary tumor-bearing rats with 2-methoxyestradiol (2-MeE2) on the urinary excretion of 12 phytoestrogens was investigated and compared with the changes in urinary excretion of estradiol metabolites. Alterations of excretion were registered for isoflavonoids, lignans and coumestans. However, due to large variations statistical significant differences were found only for two lignans, i.e. significant increases of enterodiol and matairesinol. Since the single components of phytoestrogens showed diverse alterations, excretions were expressed also by the ratio of total isoflavonoids to total lignans and compared with the estrogen ratios 2-hydroxyestrone to 16alpha-hydroxyestrone and A-ring to D-ring metabolites. The ratio of isoflavonoids to lignans was consistently decreased, whereas both ratios of estradiol metabolites were highly increased. The latter effect is probably due to demethylation of 2-methoxyestrone resulting in high catechol estrogen levels in urine. These results suggest that the high levels of catechol estrogens, produced by 2-MeE2 treatment, may have influenced the urinary excretion pattern of phytoestrogens.

Effects of high-dose soy isoflavones and equol on reproductive tissues in female cynomolgus monkeys

Soy isoflavonoids have well-established estrogenic properties in cell culture and rodent models, raising concerns that high isoflavonoid intake may promote development of uterine and breast cancers. To address this concern we evaluated the effects of high-dose isoflavonoid supplements on reproductive tissues in a postmenopausal primate model. Thirty adult female ovariectomized monkeys (Macaca fascicularis) were randomized to receive a control diet 1) alone, 2) with 509 mg/day of the soy isoflavones genistein and daidzein (IF), or 3) with 1020 mg/day of racemic equol (EQ), an isoflavan, for approximately 1 mo. Doses are expressed in aglycone units as calorically scaled human equivalents. Total serum isoflavonoid levels 4 h postfeeding were <20 nmol/L, 2570.7 nmol/L, and 6944.8 nmol/L for control, IF, and EQ groups, respectively. Equol was the predominant serum isoflavonoid in both IF (72.5%) and EQ (99.7%) groups. Aglycones represented 0.9% (IF) and 0.5% (EQ) of total serum isoflavonoids. Histologically, uteri and mammary glands were diffusely atrophic in all groups. Uterine weight, endometrial thickness, glandular area, and epithelial proliferation in the uterus were not significantly different among treatment groups (ANOVA P > 0.1 for all). Endometrial progesterone receptor gene expression was significantly increased in the IF group (P = 0.02), while protein expression was not altered (ANOVA P > 0.1). Within the mammary gland, proliferation and indicators of estrogen exposure did not differ among treatment groups (ANOVA P > 0.1 for all). These findings indicate that high doses of dietary soy isoflavonoids have minimal uterotrophic or mammotrophic effects in an established primate model.

Effects of docosahexaenoic acid supplementation on blood lipids, estrogen metabolism, and in vivo oxidative stress in postmenopausal vegetarian women

BACKGROUND

Vegetarians are generally deficient in long-chain n-3 fatty acids. Long-chain n-3 fatty acids have a beneficial effect on plasma lipid levels, and some studies showed that they had breast cancer suppression effect. One of the biomarkers of breast cancer risk is the ratio of urinary 2-hydroxyestrone (2-OHE(1)) to 16alpha-hydroxyestrone (16alpha-OHE(1)).

OBJECTIVE

To investigate the effect of docosahexaenoic acid (DHA, 22:6n-3) supplementation on blood lipids, estrogen metabolism and oxidative stress in vegetarians.

DESIGN

Single-blind, randomized, placebo-controlled trial.

INTERVENTIONS

Twenty-seven postmenopausal vegetarian women were recruited. After a 2-week run-in period with 6 g placebo corn oil, the subjects were subsequently randomized to receive either 6 g corn oil (n=13) or 6 g DHA-rich algae oil (2.14 g of DHA/day) (n=14) for 6 weeks. Two subjects in corn oil group withdrew before completion.

MAIN OUTCOME MEASURES

Plasma lipids, urinary 2-OHE(1) and 16alpha-OHE(1), urinary F(2)-isoprostanes and plasma alpha-tocopherol.

RESULTS

Plasma LDL-DHA and EPA level increased significantly by DHA supplementation. DHA decreased plasma cholesterol (C) levels (P=0.04), but did not influence the levels of plasma TG, LDL-C and HDL-C, alpha-tocopherol, urinary F(2)-isoprostanes, 2-OHE(1), 16alpha-OHE(1) and ratio of 2-OHE(1) to 16alpha-OHE(1) as compared to corn oil.

CONCLUSION

DHA supplementation at a dose of 2.14 g/day for 42 days decreases plasma cholesterol but neither does it show beneficial effects on estrogen metabolism, nor does it induce deleterious effects on the observed in vivo antioxidant or oxidative stress marker in postmenopausal vegetarian women.

SPONSORSHIP

A grant (# DOH89-TD-1062) from Department of Health, Executive Yuan, Taiwan.

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

BACKGROUND

Observational studies suggest that dietary isoflavones reduce breast cancer risk, and this may be caused in part by effects on endogenous hormone concentrations. Because intestinal bacteria metabolize isoflavones, it was hypothesized that consumption of probiotic bacteria would enhance the biologic effects of isoflavones, including effects on endogenous hormones.

DESIGN

Twenty (20) postmenopausal breast cancer survivors and 20 healthy postmenopausal women completed four 42-day diet periods in a randomized, crossover design. They received one of the following: isolated soy protein; isolated milk protein; soy + probiotic capsules; or milk + probiotic capsules. Each protein supplement provided 0.38 g protein/(kg body weight/day) (26.6 +/- 4.5 g protein/day) and soy protein provided 0.64 mg isoflavones/(kg body weight/day) (44.4 +/- 7.5 mg isoflavones/day). Probiotic capsules provided 10(9) colony-forming units Lactobacillus acidophilus (strain DDS-1), Bifidobacterium longum, and 15-20 mg fructo-oligosaccharide.

MEASURES

Plasma samples were collected at baseline and after each diet for analysis of estrogens, follicle-stimulating hormone (FSH), androgens, and sex hormone?binding globulin (SHBG).

RESULTS

Hormone levels were not affected by soy, probiotic supplements, or equol producer status, and neither cancer status nor equol producer status altered the effects of soy or probiotics. Furthermore probiotics did not alter the effects of soy consumption. Soy protein tended to decrease SHBG compared to milk protein diets (p = 0.05), although both proteins significantly decreased SHBG relative to baseline (p = 0.0001 and p = 0.03).

CONCLUSIONS

These data suggest that short-term, moderate consumption of isoflavone-containing soy protein and consumption of these particular probiotic capsules do not significantly alter reproductive hormone concentrations in breast cancer survivors or controls, regardless of equol producer status.