Enterodiol and enterolactone, two major diet-derived polyphenol metabolites have different impact on ERalpha transcriptional activation in human breast cancer cells

Associations of urinary phytoestrogens with all-cause and cardiovascular mortality in adults: a population-based cohort study

Background

The overall understanding of the correlations between mortality risk and phytoestrogens in general population remains limited. We examined the association between urinary phytoestrogen levels and all-cause and cardiovascular mortality based on the National Health and Nutrition Examination Survey (NHANES).

Methods

Weighted Cox proportional hazard regression models were employed to calculate adjusted hazard ratios (HRs) and their 95% confidence intervals (CIs). Nonlinear relationships were assessed using multivariable-adjusted restricted cubic splines (RCS).

Results

In the fully adjusted model, the highest quartiles of urinary genistein levels were correlated with significantly elevated all-cause (HR = 1.36, 95%CI: 1.16-1.59) and cardiovascular (HR = 1.58, 95%CI: 1.20-2.09) mortality. Urinary enterolactone levels in the third quartile were associated with reduced all-cause (HR = 0.77, 95%CI: 0.65-0.90) and cardiovascular (HR = 0.74, 95%CI: 0.55-0.99) mortality. In the highest quartiles of urinary daidzein levels, the cardiovascular mortality was significantly increased (HR = 1.44, 95%CI: 1.09-1.90). RCS showed an non-linear relationship between urinary daidzein levels and all-cause mortality (P = 0.04).

Conclusion

In the context of a nationally representative sample, genistein exhibited associations with elevated all-cause and cardiovascular mortality, whereas enterolactone showed an association with reduced mortality. The dose-response relationship between urinary daidzein levels and all-cause mortality as well as sex-specific disparities in the impact of phytoestrogen levels should be considered.

Development of a (Poly)phenol Metabolic Signature for Assessing (Poly)phenol-Rich Dietary Patterns

The objective assessment of habitual (poly)phenol-rich diets in nutritional epidemiology studies remains challenging. This study developed and evaluated the metabolic signature of a (poly)phenol-rich dietary score (PPS) using a targeted metabolomics method comprising 105 representative (poly)phenol metabolites, analyzed in 24 h of urine samples collected from healthy volunteers. The metabolites that were significantly associated with PPS after adjusting for energy intake were selected to establish a metabolic signature using a combination of linear regression followed by ridge regression to estimate penalized weights for each metabolite. A metabolic signature comprising 51 metabolites was significantly associated with adherence to PPS in 24 h urine samples, as well as with (poly)phenol intake estimated from food frequency questionnaires and diaries. Internal and external data sets were used for validation, and plasma, spot urine, and 24 h urine samples were compared. The metabolic signature proposed here has the potential to accurately reflect adherence to (poly)phenol-rich diets, and may be used as an objective tool for the assessment of (poly)phenol intake.

Obesity-associated inflammatory macrophage polarization is inhibited by capsaicin and phytolignans

Obesity is often accompanied by increased adipose tissue inflammation, a process that is partially driven by adipose tissue-resident macrophages. In this study, we explored the potential for plant-derived dietary compounds to exert anti-inflammatory effects in macrophages that alleviate obesity-associated adipocyte dysfunction. Capsaicin (CAP), schisandrin A (SA), enterodiol (END), and enterolactone (ENL) treatment polarized J774 macrophages to an "M2" or anti-inflammatory phenotype and inhibited responses to stimulation with lipopolysaccharide (LPS). Furthermore, these compounds blocked inflammasome activation when administered just before ATP-induced NLRP3 activation, as evidenced by the abrogation of IL-1β release in mouse macrophages and human peripheral blood monocytes. The addition of CAP, SA, or ENL during the differentiation of bone marrow-derived macrophages was also sufficient to inhibit LPS-induced IL-6 and TNFα production. Finally, CAP, END, and ENL treatment during differentiation of 3T3-L1 adipocytes induced an adiponectin-high phenotype accompanied by increases in thermogenic gene expression, and conditioned media from these adipocytes inhibited LPS-induced production of IL-1β, IL-6, and TNFα from J774 macrophages. These polarizing effects were partially mediated by the elevated adiponectin and decreased syndecan-4 in the adipocyte-conditioned media. These results implicate the contribution of plant-derived dietary components to the modulation of macrophages and adipocytes in obesity.NEW & NOTEWORTHY The utility of food-based products to prevent or alleviate chronic conditions such as obesity and its associated comorbidities is an attractive approach. Capsaicin, schisandrin A, enterodiol, and enterolactone, phytochemicals present in traditional medicinal food, decreased proinflammatory cytokine production from macrophages that, in turn, reduced obesity-associated adipocyte dysfunction. These results implicate the contribution of plant-derived dietary components to the modulation of macrophages and adipocytes in obesity.

Estrogen receptor-mediated health benefits of phytochemicals: a review

Estrogen receptors (ERs) are transcription factors with two subtypes: estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ), which are essential for the maintenance of human health and play a regulatory role in common diseases such as breast cancer, osteoporosis, neurodegenerative disorders, liver injuries and lung cancers. A number of phytochemicals extracted from various fruits and vegetables have been demonstrated to exhibit estrogenic effects and are termed phytoestrogens. As modulators of ERs, phytoestrogens can be involved in the prevention and treatment of multiple diseases as complementary or alternative therapeutic agents and have a variety of health benefits for humans. This article reviews the health benefits of phytoestrogens in clinical and epidemiologic studies for several diseases and also provides a detailed description of the molecular mechanisms of their action. A brief comparison of the advantages and disadvantages of natural phytochemicals compared to synthetic drugs is also presented. The role of phytoestrogens in the treatment of diseases and human health requires further research to fully realize their therapeutic potential.

Honokiol and its analogues as anticancer compounds: Current mechanistic insights and structure-activity relationship

Lignans are plant-derived polyphenolic compounds with a plethora of biological applications. Also, regarded as phytoestrogens, the lignans offer a variety of health benefits of which the anti-cancer effects are the most attractive. Honokiol is a lignan isolated from various parts of trees belonging to the genus Magnolia. The bioactivity of honokiol is attributed to its characteristic physical properties, which include small size and the presence of two phenolic groups that may interact with proteins in cell membranes via hydrophobic interactions, aromatic pi orbital co-valency, and hydrogen bonding. The hydrophobicity of honokiol enables its rapid dissolution in lipids and the crossing of physiological barriers, including the blood-brain barrier and cerebrospinal fluid. These factors contribute towards the high bioavailability of honokiol which further support its candidature in medicinal research. Therefore, the anticancer properties of honokiol are of particular interest as many of the contemporary anticancer drugs suffer from bioavailability drawbacks, which necessitates the identification and development of novel candidate molecules directed as anticancer chemotherapeutics. The antioncogenic profile of honokiol also arises from the regulation of various signalling pathways associated with oncogenesis, arresting of the cell cycle by regulation of cyclic proteins, upregulation of epithelial markers and downregulation of mesenchymal markers leading to the inhibition of epithelial-mesenchymal transition, and preventing the metastasis by restricting cell migration and invasion due to the downregulation of matrix-metalloproteinases. In this review, we discuss the anticancer properties of honokiol.

Recent status of sesaminol and its glucosides: Synthesis, metabolism, and biological activities

Sesamum indicum is a major and important oilseed crop that is believed to promote human health in many countries, especially in China. Sesame seeds contain two types of lignans: lipid-soluble lignans and water-soluble glucosylated lignans. The major glucosylated lignans are sesaminol glucosides (SGs). So far, four sesaminol isomers and four SGs are identified. During the naturally occurring process of SGs production, sesaminol is generated first from two molecules of E-coniferyl alcohol, and then the sugar is added to the sesaminol one by one, leading to production of SGs. Sesaminol can be prepared from SGs, from sesamolin, and through artificial synthesis. SGs are metabolized in the liver and intestine and are then transported to other tissues. They exhibit several biological activities, most of which are based on their antioxidant and anti-inflammatory activities. In this paper, we present an overview of the current status of research on sesaminol and SGs. We have also discussed their synthesis, preparation, metabolism, and biological activities. It has been suggested that sesaminol and SGs are important biological substances with strong antioxidant properties in vitro and in vivo and are widely used in the food industry, medicine, and cosmetic products. The recovery and utilization of SGs from sesame seed cake after oil processing will generate massive economic benefits.

Tailoring Potential Natural Compounds for the Treatment of Luminal Breast Cancer

Breast cancer (BC) is the most diagnosed cancer worldwide, mainly affecting the epithelial cells from the mammary glands. When it expresses the estrogen receptor (ER), the tumor is called luminal BC, which is eligible for endocrine therapy with hormone signaling blockade. Hormone therapy is essential for the survival of patients, but therapeutic resistance has been shown to be worrying, significantly compromising the prognosis. In this context, the need to explore new compounds emerges, especially compounds of plant origin, since they are biologically active and particularly promising. Natural products are being continuously screened for treating cancer due to their chemical diversity, reduced toxicity, lower side effects, and low price. This review summarizes natural compounds for the treatment of luminal BC, emphasizing the activities of these compounds in ER-positive cells. Moreover, their potential as an alternative to endocrine resistance is explored, opening new opportunities for the design of optimized therapies.

Honokiol inhibits the growth of hormone-resistant breast cancer cells: its promising effect in combination with metformin

Background and purpose

Primary and metastatic breast cancers still represent an unmet clinical need for improved chemotherapy and hormone therapy. Considerable attention has been paid to natural anticancer compounds, especially lignans. The study aimed to evaluate the activity of several lignans against breast cancer cells and assess the effect of leading lignans on signaling pathways in combination with metformin.

Experimental approach

Human breast cancer cell lines MCF7 (hormone-dependent), MDA-MB-231, and SKBR3 (hormone-independent) were used. A hormone-resistant MCF7/hydroxytamoxifen (HT) subline was obtained by long-term cultivation of the MCF7 line with hydroxytamoxifen. Antiproliferative activity was assessed by the MTT test; the expression of signaling pathway proteins was evaluated by immunoblotting analysis.

Findings/Results

We evaluated the antiproliferative activity of lignans in breast cancer cells with different levels of hormone dependence and determined the relevant IC50 values. Honokiol was chosen as the leading compound, and its IC50 ranged from 12 to 20 μM, whereas for other tested lignans, the IC50 exceeded 50 μM. The accumulation of cleaved PARP and a decrease in the expression of Bcl-2 and ERα in MCF7/HT were induced following the combination of honokiol with metformin.

Conclusions and implications

Honokiol demonstrated significant antiproliferative activity against both hormone-dependent breast cancer cells and lines with primary and acquired hormone resistance. The combination of honokiol with metformin is considered an effective approach to induce death in hormone-resistant cells. Honokiol is of interest as a natural compound with antiproliferative activity against breast cancers, including resistant tumors.

Proliferative response of ERα-positive breast cancer cells to 10 μM enterolactone, and the associated alteration in the transcriptomic landscape

Enterolactone (EL) is a product of gut-microbial metabolism of dietary plant lignans. Studies linking EL with breast cancer risk have bolstered investigations into its effects on the mammary epithelial cells, and the mechanisms thereof. While it binds to the estrogen receptor α; ERα, its effect on the proliferation of mammary tumor cell lines is reportedly ambivalent; depending on its concentration. The genomic correlates of EL actions also remain unexplored. Here we have elaborately studied the effect of EL on proliferation of ERα-positive, and ERα-negative cell lines. 10 µM EL significantly enhanced the growth of the ERα-positive MCF-7 or T47D breast cancer cells, but not the ERα-negative MDA-MB-231 or MDA-MB-453 cells. In MCF-7 cells, it significantly increased the expression of TFF1 mRNA, an estrogen-induced transcript. The binding of ERα to the estrogen response element within the TFF1 locus further demonstrated the pro-estrogenic effect of 10 µM EL. We further explored the genome-wide transcriptomic effect of 10 µM EL using the next generation sequencing technology (RNA-seq). Analysis of RNA-seq data obtained from vehicle (0.1% DMSO)- or 10 µM EL treated- MCF-7 cells revealed modulation of expression of diverse sets of functionally related genes, which reflected cell cycle progression. The manner in which 10 µM EL regulated the hallmark G2/M checkpoint, and estrogen-response-late genes correlated with proliferation inducing, and estrogen-like effects of EL on MCF-7 cells.

Anticancer potential of flaxseed lignans, their metabolites and synthetic counterparts in relation with molecular targets: current challenges and future perspectives

Lignans are known dietary polyphenols found in cereals, plants and seeds. Flaxseed is one of the major sources of lignans mainly existing in the form of secoisolariciresinol diglucoside (SDG) which can be metabolised by the gut microbes into secoisolariciresinol (SECO) and mammalian lignan (enterodiol and enterolactone) that are easily absorbed through the intestines. Numerous studies reveal that flaxseed lignans (FLs) can be promising chemotherapeutics/chemopreventive agents. Their anticancer activity can occur through the induction of apoptosis, inhibition of cell proliferation, and the hindering of metastasis and angiogenesis. The anti-carcinogenesis of flaxseed lignans is achieved through multiple molecular mechanisms involving biochemical entities such as cellular kinases, cell cycle mediators, transcription factors, inflammatory cytokines, reactive oxygen species, and drug transporters. This review summarizes the bioavailability of FLs, their anticancer mechanisms in relevance to molecular targets, safety, and the scope of future research. Overall, FLs can be utilized in functional foods, dietary supplements, and pharmaceuticals for the management and prevention of cancers.

Validation of ELISAs for Isoflavones and Enterolactone for Phytoestrogen Intake Assessment in the French Population

Phytoestrogens are dietary compounds with low estrogenic activity. The two main categories in the French diet are isoflavones from pulses and enterolignans metabolized by the gut flora from various lignans found in fruits, vegetables, grains, and beverages. Isoflavones and lignans have different effects on human physiology and can antagonize each other. Comprehensive lists of phytoestrogen sources were constructed based on measurements and literature data. The 24 h and 48 h dietary recalls were proposed to the volunteers of the ISOLED cohort (NCT03421184). Urine and plasma samples from these volunteers were assayed for genistein, daidzein, equol, and enterolactone. A dietary score was constructed considering the pharmacokinetic characteristics of these compounds. Correlation analyses were applied to fluid concentrations associated with dietary scores. Pearson correlations reached 0.921 (p < 0.001) for urine_IF, 0.900 (p < 0.001) for plasma_IF, 0.764 (p < 0.001) for urine_ENL, and 0.723 (p < 0.001) for plasma_ENL. ELISAs associated with careful intake assessments proved to be good tools for phytoestrogens' exposure estimation.

Phytoestrogens and Health Effects

Phytoestrogens are literally estrogenic substances of plant origin. Although these substances are useful for plants in many aspects, their estrogenic properties are essentially relevant to their predators. As such, phytoestrogens can be considered to be substances potentially dedicated to plant-predator interaction. Therefore, it is not surprising to note that the word phytoestrogen comes from the early discovery of estrogenic effects in grazing animals and humans. Here, several compounds whose activities have been discovered at nutritional concentrations in animals and humans are examined. The substances analyzed belong to several chemical families, i.e., the flavanones, the coumestans, the resorcylic acid lactones, the isoflavones, and the enterolignans. Following their definition and the evocation of their role in plants, their metabolic transformations and bioavailabilities are discussed. A point is then made regarding their health effects, which can either be beneficial or adverse depending on the subject studied, the sex, the age, and the physiological status. Toxicological information is given based on official data. The effects are first presented in humans. Animal models are evoked when no data are available in humans. The effects are presented with a constant reference to doses and plausible exposure.

Pyrimidinergic receptor P2Y6 expression is elevated in lung adenocarcinoma and is associated with poor prognosis

BACKGROUD

Previous in vitro studies have indicated that pyrimidinergic receptor P2Y6 (P2RY6, P2Y6 receptor) may function as a cancer-promoting factor in lung adenocarcinoma (LUAD). However, the prognostic significance of P2RY6 expression in LUAD has not been investigated.

OBJECTIVE

This study aimed to assess the impact of P2RY6 expression on the survival of patients with LUAD.

METHODS

First, we assessed P2RY6 mRNA and protein expression in LUAD and non-cancerous lung tissues using the online bioinformatics analysis tool GEPIA, fresh LUAD tissues, and LUAD tissue microarrays (TMAs). Second, we investigated the correlation between P2RY6 expression and clinicopathological parameters of LUAD patients based on data from The Cancer Genome Atlas (TCGA) database and TMAs. Finally, we analyzed the prognostic significance of P2RY6 expression in LUAD using the online survival analysis tool Kaplan-Meier Plotter and data from TMAs.

RESULTS

We demonstrated that P2RY6 mRNA and protein expression levels in LUAD tissues were significantly higher than those in non-cancerous lung tissues. The expression of P2RY6 in LUAD was positively correlated with poor differentiation, more lymph node metastasis, and more advanced clinical stage. Higher P2RY6 expression level was correlated with shorter survival of the LUAD patients. Univariate and multivariate Cox regression analyses indicated that higher P2RY6 tumor expression was an independent unfavorable prognostic factor for LUAD patients.

CONCLUSIONS

P2RY6 expression was elevated in LUAD and correlated with poor prognosis.

Targeting Estrogen Signaling in the Radiation-induced Neurodegeneration: A Possible Role of Phytoestrogens

Radiation for medical use is a well-established therapeutic method with an excellent prognosis rate for various cancer treatments. Unfortunately, a high dose of radiation therapy comes with its own share of side effects, causing radiation-induced non-specific cellular toxicity; consequently, a large percentage of treated patients suffer from chronic effects during the treatment and even after the post-treatment. Accumulating data evidenced that radiation exposure to the brain can alter the diverse cognitive-related signaling and cause progressive neurodegeneration in patients because of elevated oxidative stress, neuroinflammation, and loss of neurogenesis. Epidemiological studies suggested the beneficial effect of hormonal therapy using estrogen in slowing down the progression of various neuropathologies. Despite its primary function as a sex hormone, estrogen is also renowned for its neuroprotective activity and could manage radiation-induced side effects as it regulates many hallmarks of neurodegenerations. Thus, treatment with estrogen and estrogen-like molecules or modulators, including phytoestrogens, might be a potential approach capable of neuroprotection in radiation-induced brain degeneration. This review summarized the molecular mechanisms of radiation effects and estrogen signaling in the manifestation of neurodegeneration and highlighted the current evidence on the phytoestrogen mediated protective effect against radiationinduced brain injury. This existing knowledge points towards a new area to expand to identify the possible alternative therapy that can be taken with radiation therapy as adjuvants to improve patients' quality of life with compromised cognitive function.

A biochemical perspective on the fate of virgin olive oil phenolic compounds in vivo

The chemistry of the phenolic compounds found in virgin olive oil (VOO) is very complex due, not only to the different classes of polyphenols that can be found in it, but, above all, due to the existence of a very specific phenol class found only in oleaceae plants: the secoiridoids. Searching in the Scopus data base the keywords flavonoid, phenolic acid, lignin and secoiridoid, we can find a number of 148174, 79435, 11326 and 1392 research articles respectively, showing how little is devote to the latter class of compounds. Moreover, in contrast with other classes, that include only phenolic compounds, secoiridoids may include phenolic and non-phenolic compounds, being the articles concerning phenolic secoiridoids much less than the half of the abovementioned articles. Therefore, it is important to clarify the structures of these compounds and their chemistry, as this knowledge will help understand their bioactivity and metabolism studies, usually performed by researchers with a more health science's related background. In this review, all the structures found in many research articles concerning VOO phenolic compounds chemistry and metabolism was gathered, with a special attention devoted to the secoiridoids, the main phenolic compound class found in olives, VOO and olive leaf.

A comprehensive review of flaxseed (Linum usitatissimum L.): health-affecting compounds, mechanism of toxicity, detoxification, anticancer and potential risk

Flaxseed consumption (Linum usitatissimum L.) has increased due to its potential health benefits, such as protection against inflammation, diabetes, cancer, and cardiovascular diseases. However, flaxseeds also contains various anti-nutritive and toxic compounds such as cyanogenic glycosides, and phytic acids etc. In this case, the long-term consumption of flaxseed may pose health risks due to these non-nutritional substances, which may be life threatening if consumed in high doses, although if appropriately utilized these may prevent/treat various diseases by preventing/inhibiting and or reversing the toxicity induced by other compounds. Therefore, it is necessary to remove or suppress the harmful and anti-nutritive effects of flaxseeds before these are utilized for large-scale as food for human consumption. Interestingly, the toxic compounds of flaxseed also undergoes biochemical detoxification in the body, transforming into less toxic or inactive forms like α-ketoglutarate cyanohydrin etc. However, such detoxification is also a challenge for the development, scalability, and real-time quantification of these bioactive substances. This review focuses on the health affecting composition of flaxseed, along with health benefits and potential toxicity of its components, detoxification methods and mechanisms with evidence supported by animal and human studies.

Endocrine disruptors on and in fruits and vegetables: Estimation of the potential exposure of the French population

Fruits and vegetables are considered to be healthy compared to fats, carbohydrates, and meats. However, their production involves plant protection products (PPPs) or they can contain phytoestrogens which may exhibit endocrine effects. Thus, the exposure to the main PPPs and to phytoestrogens known as endocrine disruptors (EDs) is estimated. PPPs include fungicides, growth substances, herbicides, and insecticides authorised in France. ED-PPPs exposure is estimated from the maximum residue limits (MRLs) of 70 potential ED-PPPs used in France on 64 fruits and vegetables. The estimated exposure to potential ED-PPPs is 509 µg/d and involves agonist and antagonist substances in complex mixtures. Anti-androgens are preeminent, at 353 µg/d. Exposure to genistein and daidzein is calculated from 140 measurements in 9 categories of food-items containing soy. The global exposure to isoflavones in France is evaluated at 6700 µg/d. Phytoestrogen exposure is much higher than that of ED-PPPs. Their endocrine effects should be considered.

Pharmacological Properties to Pharmacological Insight of Sesamin in Breast Cancer Treatment: A Literature-Based Review Study

The use of dietary phytochemical rather than conventional therapies to treat numerous cancers is now a well-known approach in medical science. Easily available and less toxic dietary phytochemicals present in plants should be introduced in the list of phytochemical-based treatment areas. Sesamin, a natural phytochemical, may be a promising chemopreventive agent aiming to manage breast cancer. In this study, we discussed the pharmacological properties of sesamin that determine its therapeutics opportunity to be used in breast cancer treatment and other diseases. Sesamin is available in medicinal plants, especially in Sesamum indicum, and is easily metabolized by the liver. To better understand the antibreast cancer consequence of sesamin, we postulate some putative pathways related to the antibreast cancer mechanism: (1) regulation of estrogen receptor (ER-α and ER-β) activities, (2) suppressing programmed death-ligand 1 (PD-L1) overexpression, (3) growth factor receptor inhibition, and (4) some tyrosine kinase pathways. Targeting these pathways, sesamin can modulate cell proliferation, cell cycle arrest, cell growth and viability, metastasis, angiogenesis, apoptosis, and oncogene inactivation in various in vitro and animal models. Although the actual tumor intrinsic signaling mechanism targeted by sesamin in cancer treatment is still unknown, this review summarized that this phytoestrogen suppressed NF-κB, STAT, MAPK, and PIK/AKT signaling pathways and activated some tumor suppressor protein in numerous breast cancer models. Cotreatment with γ-tocotrienol, conventional drugs, and several drug carriers systems increased the anticancer potentiality of sesamin. Furthermore, sesamin exhibited promising pharmacokinetics properties with less toxicity in the bodies. Overall, the shreds of evidence highlight that sesamin can be a potent candidate to design drugs against breast cancer. So, like other phytochemicals, sesamin can be consumed for better therapeutic advantages due to having the ability to target a plethora of molecular pathways until clinically trialed standard drugs are not available in pharma markets.

The Beneficial Role of Natural Endocrine Disruptors: Phytoestrogens in Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia with a growing incidence rate primarily among the elderly. It is a neurodegenerative, progressive disorder leading to significant cognitive loss. Despite numerous pieces of research, no cure for halting the disease has been discovered yet. Phytoestrogens are nonestradiol compounds classified as one of the endocrine-disrupting chemicals (EDCs), meaning that they can potentially disrupt hormonal balance and result in developmental and reproductive abnormalities. Importantly, phytoestrogens are structurally, chemically, and functionally akin to estrogens, which undoubtedly has the potential to be detrimental to the organism. What is intriguing, although classified as EDCs, phytoestrogens seem to have a beneficial influence on Alzheimer's disease symptoms and neuropathologies. They have been observed to act as antioxidants, improve visual-spatial memory, lower amyloid-beta production, and increase the growth, survival, and plasticity of brain cells. This review article is aimed at contributing to the collective understanding of the role of phytoestrogens in the prevention and treatment of Alzheimer's disease. Importantly, it underlines the fact that despite being EDCs, phytoestrogens and their use can be beneficial in the prevention of Alzheimer's disease.

Effects of flaxseed on blood pressure, body mass index, and total cholesterol in hypertensive patients: A randomized clinical trial

OBJECTIVES

Given the antioxidant properties of flaxseed and its biologically active ingredients, this study was conducted to determine the effects of flaxseed supplementation on body mass index (BMI), blood pressure, and total cholesterol levels in patients with hypertension.

METHODS

In this triple-blind clinical trial, 112 patients, with an age range of 35 to 70 years, were randomized to 2 groups receiving 10 g (n = 45) and 30 g (n = 45) of flaxseed supplementation and 1 group receiving placebo (n = 45) for 12 weeks by stratified block randomization. They were evaluated in terms of systolic (SBP) and diastolic blood pressure (DBP), BMI, and total serum cholesterol. Physical activity was measured using the International Physical Activity Questionnaire-Short Form (IPAQ-SF) and food intake was assessed using the Food Frequency Questionnaire (FFQ). The data were analyzed with SPSS, version 22, using the chi-square, Kruskal-Wallis, repeated measures analysis, ANOVA, and ANCOVA tests.

RESULTS

The interaction effects among the study groups and time on the mean SBP (p = 0.001), DBP (p = 0.001), total cholesterol level (p = 0.032), and BMI (p < 0.001) were significant. During the study, the 30-g group achieved the best results, so that a 13.38-unit decrease in SBP was observed compared to a 1.72 unit increase in the placebo group and a 5.6-unit decrease in DBP was measured compared to a 2.39 unit increase in the placebo group. BMI decreased by 0.86 units compared to 0.06 units in the placebo group. Total cholesterol also decreased by 20.4 units compared to 11.86 units in the placebo group.

CONCLUSION

The results of this study showed that flaxseed can be effective in reducing blood pressure, total cholesterol, and body mass index in hypertensive patients in a twelve-week period.

Bioaccessibility and bioavailability of calcium in sprouted brown and golden flaxseed

BACKGROUND

Germination promotes changes in the composition of seeds by providing potential nutritional and health benefits compared with unsprouted seeds. This study investigated the influence of germination on the bioaccessibility and bioavailability of calcium in brown flaxseed (BF) and golden flaxseed (GF).

RESULTS

Germination did not influence the calcium levels of BF or GF, but the sprouted GF (SGF, 265.6 ± 12.9 mg) presented higher levels of calcium than the sprouted BF (SBF, 211.6 ± 3.20 mg). Tannin levels were similar among the groups (GF = 79.97 ± 3.49 mg; SGF = 78.81 ± 0.77 mg; BF = 81.82 ± 2.61 mg; SBF = 79.24 ± 4.58 mg), whereas phytate and oxalate levels decreased after germination. Germination reduced the phytate:calcium and oxalate:calcium molar ratios. In the in vitro study, germination increased calcium bioaccessibility (GF = 35.60 mg versus SGF = 41.45 mg; BF = 31.01 mg versus SBF = 38.84 mg). In the in vivo study, all groups present similar levels of urinary calcium (GF = 1.04 mg versus SGF = 2.06 mg; BF = 1.68 mg versus SBF = 1.35 mg) and fecal calcium (GF = 5.06 mg versus SGF = 6.14 mg; BF = 6.47 mg versus SBF = 8.40 mg). The calcium balance/day of the SBF group (37.97 mg) was smaller than the control group (47.22 mg). The germination maintained the plasma levels of calcium, phosphorus, creatinine, and alkaline phosphatase similar among the groups. No changes were observed in morphology and calcium levels of animal femurs.

CONCLUSION

The germination reduced the antinutritional factor in both flaxseed varieties. Although there was an improvement in the in vitro bioaccessibility of calcium, the germination did not increase calcium absorption and balance in the animals, which may be due to the interaction with other compounds in the organism. © 2020 Society of Chemical Industry.

The Interactions between Polyphenols and Microorganisms, Especially Gut Microbiota

This review presents the comprehensive knowledge about the bidirectional relationship between polyphenols and the gut microbiome. The first part is related to polyphenols' impacts on various microorganisms, especially bacteria, and their influence on intestinal pathogens. The research data on the mechanisms of polyphenol action were collected together and organized. The impact of various polyphenols groups on intestinal bacteria both on the whole "microbiota" and on particular species, including probiotics, are presented. Moreover, the impact of polyphenols present in food (bound to the matrix) was compared with the purified polyphenols (such as in dietary supplements) as well as polyphenols in the form of derivatives (such as glycosides) with those in the form of aglycones. The second part of the paper discusses in detail the mechanisms (pathways) and the role of bacterial biotransformation of the most important groups of polyphenols, including the production of bioactive metabolites with a significant impact on the human organism (both positive and negative).

Associations of Urinary Phytoestrogen Concentrations with Sleep Disorders and Sleep Duration among Adults

Current evidence on the relationship of phytoestrogens with sleep is limited and contradictory. In particular, studies on individual phytoestrogens and sleep have not been reported. Thus, this study aimed to appraise the associations of individual phytoestrogens with sleep disorders and sleep duration. This cross-sectional study comprising 4830 adults utilized data from the National Health and Nutrition Examination Survey 2005-2010. Phytoestrogens were tested in urine specimens. Sleep disorders and sleep duration were based on a self-reported doctor's diagnosis and usual sleep duration. The main analyses utilized logistic and multinomial logistic regression models and a restricted cubic spline. In the fully adjusted model, compared with tertile 1 (lowest), the odds ratios (95% confidence intervals (CIs)) of sleep disorders for the highest tertile of urinary concentrations of enterolactone, enterodiol, and O-desmethylangolensin were 0.64 (0.41-1.00), 1.54 (1.07-2.21), and 1.89 (1.26-2.85), respectively. Linear inverse, approximatively linear positive, and inverted L-shaped concentration-response relationships were found between enterolactone, enterodiol, and O-desmethylangolensin and sleep disorders, respectively. Compared with normal sleep (7-8 h/night), the relative risk ratio (RRR) (95% CI) of very short sleep for enterolactone was 0.56 (0.36-0.86), and the RRR (95% CI) of long sleep risk for genistein was 0.62 (0.39-0.99). Furthermore, negative associations of genistein with sleep disorders and enterolactone with long sleep risk, as well as positive associations of enterodiol with both long and very short sleep, were observed in the stratified analysis by age or gender. Finally, a notable finding was that urinary O-desmethylangolensin concentration was positively related to sleep disorders in both females aged 40-59 years and non-Hispanic Whites but inversely associated with sleep disorders in both females aged 60 years or over and other Hispanics. Our findings suggested that enterolactone and genistein might be beneficial for preventing sleep disorders or non-normal sleep duration among adults, and enterodiol might be adverse toward this goal. However, the association of O-desmethylangolensin with sleep disorders might be discrepant in different races and females of different ages.

The Microbiome-Estrogen Connection and Breast Cancer Risk

The microbiome is undoubtedly the second genome of the human body and has diverse roles in health and disease. However, translational progress is limited due to the vastness of the microbiome, which accounts for over 3.3 million genes, whose functions are still unclear. Numerous studies in the past decade have demonstrated how microbiome impacts various organ-specific cancers by altering the energy balance of the body, increasing adiposity, synthesizing genotoxins and small signaling molecules, and priming and regulating immune response and metabolism of indigestible dietary components, xenobiotics, and pharmaceuticals. In relation to breast cancer, one of the most prominent roles of the human microbiome is the regulation of steroid hormone metabolism since endogenous estrogens are the most important risk factor in breast cancer development especially in postmenopausal women. Intestinal microbes encode enzymes capable of deconjugating conjugated estrogen metabolites marked for excretion, pushing them back into the enterohepatic circulation in a biologically active form. In addition, the intestinal microbes also break down otherwise indigestible dietary polyphenols to synthesize estrogen-like compounds or estrogen mimics that exhibit varied estrogenic potency. The present account discusses the potential role of gastrointestinal microbiome in breast cancer development by mediating metabolism of steroid hormones and synthesis of biologically active estrogen mimics.

n-3 PUFA Sources (Precursor/Products): A Review of Current Knowledge on Rabbit

This review compares the effects of different n-3 polyunsaturated fatty acid (PUFA) sources on biological activity, physiological/reproductive endpoints, and health implications with a special emphasis on a rabbit case study. Linoleic acid (LA) and α-linolenic acid (ALA) are members of two classes of PUFAs, namely the n-6 and n-3 series, which are required for normal human health. Both are considered precursors of a cascade of molecules (eicosanoids), which take part in many biological processes (inflammation, vasoconstriction/vasodilation, thromboregulation, etc.). However, their biological functions are opposite and are mainly related to the form (precursor or long-chain products) in which they were administered and to the enzyme-substrate preference. ALA is widely present in common vegetable oils and foods, marine algae, and natural herbs, whereas its long-chain PUFA derivatives are available mainly in fish and animal product origins. Recent studies have shown that the accumulation of n-3 PUFAs seems mostly to be tissue-dependent and acts in a tissue-selective manner. Furthermore, dietary n-3 PUFAs widely affect the lipid oxidation susceptibility of all tissues. In conclusion, sustainable sources of n-3 PUFAs are limited and exert a different effect about (1) the form in which they are administered, precursor or derivatives; (2) their antioxidant protections; and (3) the purpose to be achieved (health improvement, physiological and reproductive traits, metabolic pathways, etc.).

Bacterial metabolism as responsible of beneficial effects of phytoestrogens on human health

Phytoestrogens (PE) are compounds found in plants such as soy (isoflavones), flax seeds and cereals (lignans) and pomegranates (ellagitannins). PE have shown estrogenic/antiestrogenic, antioxidant, anti-inflammatory, antineoplastic and apoptotic activities. The human studies are showing promising although inconsistent results about the beneficial effects of PE on ameliorating the menopausal symptoms or reducing the risk of certain cancers, cardiovascular disease or diabetes. The effects of PE on the organism are mediated by the intestinal microbiota, which transforms them into bioactive PE such as genistein, equol, enterolignans and certain urolithins. In this work, we review the most recent findings about the bacteria able to metabolize PE, together with the latest studies on the effects of PE on health. In addition, we describe the possible factors hindering the demonstration of the beneficial effect of PE on health, evincing the importance of measuring the actual circulating PE in order to encompass the variability of PE metabolism due to the intestinal microbiota. With this in mind, we also explore an approach to ensure the access to bioactive PE.

Flaxseed Lignans as Important Dietary Polyphenols for Cancer Prevention and Treatment: Chemistry, Pharmacokinetics, and Molecular Targets

Cancer causes considerable morbidity and mortality across the world. Socioeconomic, environmental, and lifestyle factors contribute to the increasing cancer prevalence, bespeaking a need for effective prevention and treatment strategies. Phytochemicals like plant polyphenols are generally considered to have anticancer, anti-inflammatory, antiviral, antimicrobial, and immunomodulatory effects, which explain their promotion for human health. The past several decades have contributed to a growing evidence base in the literature that demonstrate ability of polyphenols to modulate multiple targets of carcinogenesis linking models of cancer characteristics (i.e., hallmarks and nutraceutical-based targeting of cancer) via direct or indirect interaction or modulation of cellular and molecular targets. This evidence is particularly relevant for the lignans, an ubiquitous, important class of dietary polyphenols present in high levels in food sources such as flaxseed. Literature evidence on lignans suggests potential benefit in cancer prevention and treatment. This review summarizes the relevant chemical and pharmacokinetic properties of dietary polyphenols and specifically focuses on the biological targets of flaxseed lignans. The consolidation of the considerable body of data on the diverse targets of the lignans will aid continued research into their potential for use in combination with other cancer chemotherapies, utilizing flaxseed lignan-enriched natural products.

A Review of Phytoestrogens and Their Association With Pelvic Floor Conditions

INTRODUCTION

Urinary incontinence, pelvic organ prolapse, and fecal incontinence are pelvic floor disorders (PFDs) disproportionately experienced by postmenopausal women. Limited data exist suggesting that phytoestrogens may have an impact on the pathophysiology and symptom of PFDs.

PURPOSE OF REVIEW

The aim of the study was to review the current literature addressing the role of phytoestrogens on PFDs, including the pathophysiology, symptom, treatment, and possible prevention.

FINDINGS

Qualifying literature spans from 2003 to 2017 and included 14 studies ranging from in vitro, animal, and observational studies to randomized clinical trials.

SUMMARY

Although the literature is limited, most studies on phytoestrogens and PFDs support associations with pathophysiologic mechanisms, symptoms, and treatment for urinary incontinence and pelvic organ prolapse, but not fecal incontinence. Less is known regarding the prevention of PFDs with phytoestrogen intake over time. Overall, the potential influence of phytoestrogens on PFDs is not well understood, and more research is needed.

A Review of Lignan Metabolism, Milk Enterolactone Concentration, and Antioxidant Status of Dairy Cows Fed Flaxseed

Lignans are polyphenolic compounds with a wide spectrum of biological functions including antioxidant, anti-inflammatory, and anticarcinogenic activities, therefore, there is an increasing interest in promoting the inclusion of lignan-rich foods in humans' diets. Flaxseed is the richest source of the lignan secoisolariciresinol diglucoside-a compound found in the outer fibrous-containing layers of flax. The rumen appears to be the major site for the conversion of secoisolariciresinol diglucoside to the enterolignans enterodiol and enterolactone, but only enterolactone has been detected in milk of dairy cows fed flaxseed products (whole seeds, hulls, meal). However, there is limited information regarding the ruminal microbiota species involved in the metabolism of secoisolariciresinol diglucoside. Likewise, little is known about how dietary manipulation such as varying the nonstructural carbohydrate profile of rations affects milk enterolactone in dairy cows. Our review covers the gastrointestinal tract metabolism of lignans in humans and animals and presents an in-depth assessment of research that have investigated the impacts of flaxseed products on milk enterolactone concentration and animal health. It also addresses the pharmacokinetics of enterolactone consumed through milk, which may have implications to ruminants and humans' health.

Dietary flaxseed: what we know and don't know about its effects on cardiovascular disease

Flaxseed (Linum usitatissimum) is composed of a unique combination of bioactive components that appear to generate, through either an isolated or a synergistic action, a significant beneficial effect on the cardiovascular system. With a significant increase in the generation of data on the dietary impact of flaxseed on the cardiovascular system, a review of where we stand - what we know and what we still need to understand about these effects on the heart and the vasculature - was thought to be of value and the rationale for this paper. For example, although we now know how to deliver the bioactives most efficiently (oil versus ground seed versus whole seed), we do not know how different foods can influence that delivery. Further, we know flaxseed has anti-arrhythmic, anti-atherogenic, anti-hypertensive, and cholesterol-lowering actions in animal studies and some selected human trials but much more needs to be learned, particularly in human trials. These results have justified further commitment of resources to the initiation of human trials. Because of the impact of nutrition on many chronic diseases, this may not only be true for the effects of flaxseed on cardiovascular disease but may be just as relevant for many other disease conditions.

Effect of Dietary Flaxseed Intake on Circulating Sex Hormone Levels among Postmenopausal Women: A Randomized Controlled Intervention Trial

Lignan intake, and its richest food source, flaxseed, have been associated with reduced breast cancer risk. Endogenous sex hormones, such as estrogens, play a role in breast cancer development, and lignans may alter these sex hormone levels. To assess the effect of flaxseed on circulating sex hormones, a randomized controlled trial was conducted among 99 postmenopausal women in Toronto, Canada. The intervention arm consumed 2 tablespoons (15 g) of ground flaxseed daily for 7 weeks; the control arm maintained usual diet. Baseline and week 7 concentrations of 14 serum sex hormones were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and immunoassay, and serum enterolignans (lignan biomarker) using LC-MS/MS. Intervention effects on sex hormone levels were assessed using analysis of covariance. Serum enterolignans increased among the flaxseed arm (+516%). Women consuming flaxseed (vs. controls) had increased serum 2-hydroxyestrone [treatment effect ratio (TER) = 1.54; 95% CI: 1.18-2.00] and 2:16α-hydroxyestrone ratio (TER =1.54; 95% CI: 1.15-2.06); effects on other hormones were not statistically significant. Within the flaxseed arm, change in enterolignan level was positively correlated with changes in 2-hydroxyestrone and 2:16α-hydroxyestrone ratio, and negatively with prolactin. Findings suggest flaxseed affects certain circulating sex hormone levels with possible implications for future breast cancer prevention research.

The flaxseed lignan secoisolariciresinol diglucoside decreases local inflammation, suppresses NFκB signaling, and inhibits mammary tumor growth

PURPOSE

Exposure to the polyphenolic plant lignan secoisolariciresinol diglucoside (SDG) and its metabolite enterolactone (ENL) has been associated with reduced breast cancer progression, particularly for estrogen receptor alpha (ERα)-negative disease, and decreased preclinical mammary tumor growth. However, while preclinical studies have established that SDG and ENL affect measures of progression in models of triple-negative breast cancer (TNBC, a subset of ERα-negative disease), the molecular mechanisms underlying these effects remain unclear.

METHODS

C57BL/6 mice were fed a control diet (control, 10% kcal from fat) or control diet + SDG (SDG, 100 mg/kg diet) for 8 weeks, then orthotopically injected with syngeneic E0771 mammary tumor cells (a model of TNBC); tumor growth was monitored for 3 weeks. The role of reduced NF-κB signaling in SDG's anti-tumor effects was explored in vitro via treatment with the bioactive SDG metabolite ENL. In addition to the murine E0771 cells, the in vitro studies utilized MDA-MB-231 and MCF-7 cells, two human cell lines which model the triple-negative and luminal A breast cancer subtypes, respectively.

RESULTS

SDG supplementation in the mice significantly reduced tumor volume and expression of phospho-p65 and NF-κB target genes (P < 0.05). Markers of macrophage infiltration were decreased in the distal-to-tumor mammary fat pad of mice supplemented with SDG relative to control mice (P < 0.05). In vitro, ENL treatment inhibited viability, survival, and NF-κB activity and target gene expression in E0771, MDA-MB-231, and MCF-7 cells (P < 0.05). Overexpression of Rela attenuated ENL's inhibition of E0771 cell viability and survival.

CONCLUSIONS

SDG reduces tumor growth in the E0771 model of TNBC, likely via a mechanism involving inhibition of NF-κB activity. SDG could serve as a practical and effective adjuvant treatment to reduce recurrence, but greater understanding of its effects is needed to inform the development of more targeted recommendations for its use.

Soy, Soy Foods and Their Role in Vegetarian Diets

Soy is a basic food ingredient of traditional Asian cuisine used for thousands of years. In Western countries, soybeans have been introduced about a hundred years ago and recently they are mainly used for surrogate foods production. Soy and soy foods are common nutritional solutions for vegetarians, due to their high protein content and versatility in the production of meat analogues and milk substitutes. However, there are some doubts about the potential effects on health, such as the effectiveness on cardiovascular risk reduction or, conversely, on the possible disruption of thyroid function and sexual hormones. The soy components that have stimulated the most research interest are isoflavones, which are polyphenols with estrogenic properties highly contained in soybeans. In this review, we discuss the characteristics of soy and soy foods, focusing on their nutrient content, including phytoestrogens and other bioactive substances that are noteworthy for vegetarians, the largest soy consumers in the Western countries. The safety of use will also be discussed, given the growing trend in adoption of vegetarian styles and the new soy-based foods availability.

Differential and directional estrogenic signaling pathways induced by enterolignans and their precursors

Mammalian lignans or enterolignans are metabolites of plant lignans, an important category of phytochemicals. Although they are known to be associated with estrogenic activity, cell signaling pathways leading to specific cell functions, and especially the differences among lignans, have not been explored. We examined the estrogenic activity of enterolignans and their precursor plant lignans and cell signaling pathways for some cell functions, cell cycle and chemokine secretion. We used DNA microarray-based gene expression profiling in human breast cancer MCF-7 cells to examine the similarities, as well as the differences, among enterolignans, enterolactone and enterodiol, and their precursors, matairesinol, pinoresinol and sesamin. The profiles showed moderate to high levels of correlation (R values: 0.44 to 0.81) with that of estrogen (17β-estradiol or E₂). Significant correlations were observed among lignans (R values: 0.77 to 0.97), and the correlations were higher for cell functions related to enzymes, signaling, proliferation and transport. All the enterolignans/precursors examined showed activation of the Erk1/2 and PI3K/Akt pathways, indicating the involvement of rapid signaling through the non-genomic estrogen signaling pathway. However, when their effects on specific cell functions, cell cycle progression and chemokine (MCP-1) secretion were examined, positive effects were observed only for enterolactone, suggesting that signals are given in certain directions at a position closer to cell functions. We hypothesized that, while estrogen signaling is initiated by the enterolignans/precursors examined, their signals are differentially and directionally modulated later in the pathways, resulting in the differences at the cell function level.

Intestinal Proportion of Blautia sp. is Associated with Clinical Stage and Histoprognostic Grade in Patients with Early-Stage Breast Cancer

Improving knowledge about breast cancer etiology is crucial in order to propose prevention strategies for this pathology. Gut microbiota is involved in numerous physiopathological situations including cancers. Although its potential involvement in breast cancer through the alteration of the enterohepatic circulation of estrogens and/or the metabolism of phytoestrogens has been discussed for some time, it remains to be demonstrated. The present study seeks to strengthen this hypothesis by identifying possible links between the fecal microbiota composition and clinical characteristics in breast cancer patients. Bacterial DNA was extracted from the feces of 31 patients with early-stage breast cancer and amplified by real-time polymerase chain reaction (qPCR), targeting 16S rRNA sequences specific to bacterial groups, and then analyzed in relation to clinical characteristics. The absolute numbers of total bacteria and of three bacterial groups (Firmicutes, Faecalibacterium prausnitzii, and Blautia) differed significantly according to the patient's body mass index. The percentage and the absolute numbers of certain bacterial groups, namely C. coccoides, F. prausnitzii, and Blautia, differed significantly according to the clinical stages and the histoprognostic grades. Our study highlighted that intestinal microbiota composition in these patients differs according to clinical characteristics and BMI. Further studies are required to clarify the link between breast cancer and intestinal microbiota.

Performance and egg quality of laying hens fed flaxseed: highlights on n-3 fatty acids, cholesterol, lignans and isoflavones

Flaxseed is a rich source of α-linolenic acid and phytoestrogens, mainly lignans, whose metabolites (enterodiol and enterolactone) can affect estrogen functions. The present study evaluated the influence of dietary flaxseed supplementation on reproductive performance and egg characteristics (fatty acids, cholesterol, lignans and isoflavones) of 40 Hy-Line hens (20/group) fed for 23 weeks a control diet or the same diet supplemented with 10% of extruded flaxseed. The flaxseed diet had approximately three times the content of lignans (2608.54 ng/g) as the control diet, mainly secoisolariciresinol diglucoside (1534.24 v. 494.72 ng/g). When compared with the control group, hens fed flaxseed showed a similar deposition rate (72.0% v. 73.9%) and egg yield. Furthermore, there was no effect of flaxseed on the main chemical composition of the egg and on its cholesterol content. Estradiol was higher in the plasma of the control group (1419.00 v. 1077.01 pg/ml) probably due to the effect of flaxseed on phytoestrogen metabolites. The plasma lignans were higher in hens fed flaxseed, whereas isoflavones were lower, mainly due to the lower equol value (50.52 v. 71.01 ng/ml). A similar trend was shown in eggs: the flaxseed group had higher level of enterodiol and enterolactone, whereas the equol was lower (198.31 v. 142.02 ng/g yolk). Secoisolariciresinol was the main lignan in eggs of the flaxseed group and its concentration was three times higher then control eggs. Flaxseed also improved the n-3 long-chain polyunsaturated fatty acids of eggs (3.25 v. 0.92 mg/g egg), mainly DHA, however, its oxidative status (thiobarbituric reactive substances) was negatively affected. In conclusion, 10% dietary flaxseed did not affect the productive performance of hens or the yolk cholesterol concentration, whereas the lignans and n-3 polyunsaturated fatty acid content of eggs improved. Further details on the competition between the different dietary phytoestrogens and their metabolites (estrogen, equol, enterodiol and enterolactone) should be investigated.

Bioactivation of Phytoestrogens: Intestinal Bacteria and Health

Phytoestrogens are polyphenols similar to human estrogens found in plants or derived from plant precursors. Phytoestrogens are found in high concentration in soya, flaxseed and other seeds, fruits, vegetables, cereals, tea, chocolate, etc. They comprise several classes of chemical compounds (stilbenes, coumestans, isoflavones, ellagitannins, and lignans) which are structurally similar to endogenous estrogens but which can have both estrogenic and antiestrogenic effects. Although epidemiological and experimental evidence indicates that intake of phytoestrogens in foods may be protective against certain chronic diseases, discrepancies have been observed between in vivo and in vitro experiments. The microbial transformations have not been reported so far in stilbenes and coumestans. However, isoflavones, ellagitanins, and lignans are metabolized by intestinal bacteria to produce equol, urolithins, and enterolignans, respectively. Equol, urolithin, and enterolignans are more bioavailable, and have more estrogenic/antiestrogenic and antioxidant activity than their precursors. Moreover, equol, urolithins and enterolignans have anti-inflammatory effects and induce antiproliferative and apoptosis-inducing activities. The transformation of isoflavones, ellagitanins, and lignans by intestinal microbiota is essential to be protective against certain chronic diseases, as cancer, cardiovascular disease, osteoporosis, and menopausal symptoms. Bioavailability, bioactivity, and health effects of dietary phytoestrogens are strongly determined by the intestinal bacteria of each individual.

Short communication: Concentrations of the mammalian lignan enterolactone in preovulatory follicles and the correlation with intrafollicular estradiol in dairy cows fed extruded flaxseed

Flaxseed is a rich source of lignans that can be metabolized to the mammalian lignan enterolactone (EL), which may elicit weak estrogenic or antiestrogenic effects. The objectives of this study were to examine the effects of feeding an extruded flaxseed supplement to dairy cows on concentrations of EL in plasma and preovulatory follicles and the association with intrafollicular estradiol (E2). Twenty-four multiparous 256-d-pregnant Israeli Holstein cows were fed either a standard diet both pre- and postpartum (control; n=12) or provided with an extruded flaxseed supplement (n=12), at 7.9 and 9.2% of dry matter, pre- and postpartum, respectively. Follicular fluid (FF) aspirations were conducted at 84±16 d in lactation as follows: 7 to 8 d following behavioral estrus, cows were injected with prostaglandin F2α and 48h later follicles >7mm were aspirated. Follicles were regarded as preovulatory when the E2-to-progesterone ratio was >1. Plasma EL concentrations were not different between treatment groups; however, concentrations of EL in FF of preovulatory follicles were 1.7 times higher in extruded flaxseed-supplemented cows than in control. Across-treatment analysis revealed a positive correlation between concentrations of EL in plasma and in FF. In addition, intrafollicular EL concentrations were positively correlated with E2 concentrations (r=0.50), and with the intrafollicular E2-to-progesterone ratio. In conclusion, supplementing dairy cows with extruded flaxseed increased EL concentrations in preovulatory follicles. Intrafollicular EL was correlated with E2 concentrations; therefore, the possible effects of EL from flaxseed on follicular steroidogenesis should be considered.

Effects of Flaxseed Lignan Secoisolariciresinol Diglucosideon Preneoplastic Biomarkers of Cancer Progression in a Model of Simultaneous Breast and Ovarian Cancer Development

Breast cancer prevention efforts are focused increasingly on potentially beneficial dietary modifications due to their ease of implementation and wide acceptance. Secoisolariciresinol diglucoside (SDG) is a lignan found in high concentration in flaxseed that may have selective estrogen receptor modulator-like effects resulting in antiestrogenic activity in a high estrogen environment. In parallel with a human phase II prevention trial, female ACI rats (n = 8-10/group) received 0, 10, or 100 ppm SDG in the feed. The 100 ppm SDG treatment produced similar blood lignan levels as those observed in our human pilot study. Mammary and ovarian cancer progression were induced using local ovarian DMBA treatment and subcutaneous sustained release 17β-estradiol administered starting at 7 weeks of age. Mammary gland and ovarian tissues were collected at 3 mo after initiation of treatment and examined for changes in epithelial cell proliferation (Ki-67, cell counts), histopathology, and dysplasia scores, as well as expression of selected genes involved in proliferation, estrogen signaling, and cell adhesion. Treatment with SDG normalized several biomarkers in mammary gland tissue (dysplasia, cell number, and expression of several genes) that had been altered by carcinogen. There is no indication that SDG promotes preneoplastic progression in the ovarian epithelium.

Cardiometabolic risk factors are associated with high urinary enterolactone concentration, independent of urinary enterodiol concentration and dietary fiber intake in adults

The study objective was to evaluate independent and interactive associations of dietary fiber intake and high urinary enterolignans with cardiometabolic risk factors. The analysis included 2260 adults (≥20 y of age) from the 2003-2010 NHANES. Logistic regression models were used to evaluate obesity and clinically defined cardiometabolic risk factors in relation to dietary fiber intake and urinary enterolignan concentrations. Three sets of models were created: 1) independent associations, 2) mutually adjusted associations, and 3) interactions. Models were adjusted for age, gender, race/ethnicity, education, smoking status, and energy intake. High concentrations were considered to be above the 90th percentile of urinary enterolignan concentrations. Increasing dietary fiber intake was associated with high blood pressure (P = 0.02) and low serum HDL cholesterol (P-trend = 0.03). High urinary enterodiol concentration was not associated with obesity or cardiometabolic risk factors. High urinary enterolactone concentration was inversely associated with obesity (OR: 0.44; 95% CI: 0.29, 0.66), abdominal obesity (OR: 0.58; 95% CI: 0.39, 0.87), high serum C-reactive protein (CRP; OR: 0.52; 95% CI: 0.37, 0.74), high serum triglycerides (OR: 0.39; 95% CI: 0.23, 0.61), low serum HDL cholesterol (OR: 0.37; 95% CI: 0.23, 0.61), and metabolic syndrome (OR: 0.47; 95% CI: 0.30, 0.74). In mutually adjusted models, enterolactone associations observed in independent models remained similar, but associations for dietary fiber intake were attenuated, with the exception of blood pressure. In interaction models, there were 2 significant interactions: between high urinary enterodiol concentration and dietary fiber intake for high serum CRP (P = 0.04) and high plasma glucose (P = 0.04). Overall, being in the highest 10% of urinary enterolactone concentration was associated with cardiometabolic risk factors, independent of dietary fiber intake and enterodiol concentration. Future studies are warranted to evaluate physiologic actions of enterolactone or aspects of the gut microbial profile responsible for lignan metabolism to enterolactone.

Design and validation of a novel immunological test for enterolactone

Enterolactone (ENL) is produced by the gut microflora from lignans found in edible plants. ENL is estrogenic with no effect on the E-screen test and is a natural Selected Estrogen Receptor Modulator (SERM) with health interests that have to be checked in clinical studies with bioavailability assessment. Two haptens of ENL were synthesized, with a spacer arm at the C5 position having either 2 or 4 carbon atoms (ENLΔ2 and ENLΔ4, respectively). Hapten coupling to bovine serum albumin (BSA) was characterized by MALDI mass spectrometry. Polyclonal antibodies were obtained against the BSA conjugates. Additional conjugates were generated by coupling to swine thyroglobulin (Thyr). Homologous and heterologous competitive ELISAs were developed with Thyr or BSA conjugates as coating. The best assays were validated on biological samples from mice. Both antibodies exhibited the same IC50 at 1.5 ng mL(-1) with a detection limit below 0.5 ng mL(-1). Most cross-reactions with structurally related lignans were lower than 0.03%. This new assay type is faster, more specific and more reliable than existing ones.

Phytoestrogen and fiber intakes in relation to incident vasomotor symptoms: results from the Study of Women's Health Across the Nation

OBJECTIVE

Although reduction of vasomotor symptoms (VMS; hot flashes and night sweats) has been reported in postmenopausal women who used isoflavones, a clear dose response has not been shown, has largely not been reported for perimenopausal women, and has largely only been reported for reducing prevalent VMS, not preventing newly developing VMS. We analyzed longitudinal data from the Study of Women's Health Across the Nation for the relation of dietary phytoestrogen and fiber intake to incident VMS in this multiracial/ethnic cohort.

METHODS

The Study of Women's Health Across the Nation included 3,302 premenopausal and early perimenopausal women, 1,651 of whom reported no VMS at baseline and were followed with annual visits for 10 years. Dietary intakes of isoflavones, coumestrol, lignans, and fiber were assessed by a food frequency questionnaire at baseline and in annual visits 5 and 9 and interpolated for intervening years. The number of days experiencing VMS in the past 2 weeks was self-reported annually. Using multinomial logistic regression with generalized estimating equations, we modeled incident VMS in relation to isoflavones, lignans, fiber, coumestrol, or total phytoestrogen intake and covariates.

RESULTS

No consistent monotonic relations were observed between any dietary phytoestrogen or fiber and incident VMS, although adjusted odds ratios for some individual quartiles were statistically significant.

CONCLUSIONS

For certainty of any effect of dietary phytoestrogens or fiber on the prevention of incident VMS, a randomized, placebo-controlled, double-masked trial with sufficient numbers of women in different racial/ethnic, menopausal status, and metabolic groups over years of follow-up is required, but our results suggest that a clinically significant or large effect is improbable.

Plasma enterolactone and breast cancer risk in the Nurses' Health Study II

Lignans are plant-based phytoestrogens with both estrogenic and anti-estrogenic properties that may be important for breast carcinogenesis. Retrospective studies have observed decreased breast cancer risk associated with high circulating enterolactone concentrations, a biomarker of lignan intake, but results from prospective studies are conflicting. To prospectively examine this association, we measured plasma enterolactone levels in 802 breast cancer cases and 802 matched controls nested among predominantly premenopausal women in the Nurses' Health Study II cohort. We used conditional logistic regression and polytomous logistic regression models, adjusting for known breast cancer risk factors, to calculate relative risks (RR) and 95 % confidence intervals (CI). Compared to women with enterolactone concentrations ≤4 nmol/L, the multivariate-adjusted RRs for breast cancer were 1.18 (95 % CI 0.86-1.62), 0.91 (95 % CI 0.66-1.25), and 0.96 (95 % CI 0.70-1.33) for women with enterolactone levels in the second to the fourth quartiles, respectively; P trend = 0.60. Results were similar across tumors defined by estrogen and progesterone receptor status. Among premenopausal women with follicular estradiol levels below the median (<47 pg/mL), women in the highest category of enterolactone levels had a 51 % lower breast cancer risk compared to those in the lowest category (95 % CI 0.27-0.91); P trend = 0.02. No association was observed among women with high-follicular estradiol levels (≥47 pg/mL), (comparable RR = 1.39, 95 % CI 0.73-2.65; P interaction = 0.02). We did not observe an overall association between plasma enterolactone and breast cancer risk in a large nested case-control study of US women. However, a significant inverse association was observed among premenopausal women with low-follicular estradiol levels, suggesting that enterolactone may be important in a low-estrogen environment. This should be confirmed in future studies.