Soy extracts versus hormone therapy for reduction of menopausal hot flushes: indirect comparison

Soy and Gastrointestinal Health: A Review

Soybean is the most economically important legume globally, providing a major source of plant protein for millions of people; it offers a high-quality, cost-competitive and versatile base-protein ingredient for plant-based meat alternatives. The health benefits of soybean and its constituents have largely been attributed to the actions of phytoestrogens, which are present at high levels. Additionally, consumption of soy-based foods may also modulate gastrointestinal (GI) health, in particular colorectal cancer risk, via effects on the composition and metabolic activity of the GI microbiome. The aim of this narrative review was to critically evaluate the emerging evidence from clinical trials, observational studies and animal trials relating to the effects of consuming soybeans, soy-based products and the key constituents of soybeans (isoflavones, soy proteins and oligosaccharides) on measures of GI health. Our review suggests that there are consistent favourable changes in measures of GI health for some soy foods, such as fermented rather than unfermented soy milk, and for those individuals with a microbiome that can metabolise equol. However, as consumption of foods containing soy protein isolates and textured soy proteins increases, further clinical evidence is needed to understand whether these foods elicit similar or additional functional effects on GI health.

Dietary Intake of Polyphenols and the Risk of Breast Cancer: a Case-Control Study

Despite mounting evidence that dietary polyphenols might have a protective role against the risk of breast cancer (BC), few studies have assessed the relationship between intake of polyphenol classes and subclasses with BC. Thus, we examined the relationship between dietary polyphenol classes and individual polyphenol subclasses and the risk of BC. Overall, 134 newly diagnosed BC patients and 267 healthy hospitalized controls were studied. Dietary intake was assessed using a validated 168-item food frequency questionnaire (FFQ). To estimate dietary intake of polyphenols, polyphenol content (flavonoids, lignans, stilbenes and phenolic acids) of 80 food items were derived from an updated version of the phenol explorer database containing information on the effects of food processing on polyphenol content. The dietary polyphenol intake was calculated by matching the subjects' food consumption data with our polyphenol content database. Multivariate logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Controls had higher intake of total polyphenol (marginally significant; p = 0.07), hydroxycinnamic acid (marginally significant; p = 0.05) and lignan (p = 0.01). After adjusting for potential confounders, high consumption of lignans (highest vs. lowest tertile: OR, 0.51; 95% CI, 0.26–0.97; p for trend = 0.04) associated with decreased risk of BC. There was no significant relationship between intake of other polyphenols and risk of BC. Our findings suggest that high lignan intake is associated with a reduced risk of BC.

Utilization of Isoflavones in Soybeans for Women with Menopausal Syndrome: An Overview

Based on their nutrient composition, soybeans and related foods have been considered to be nutritious and healthy for humans. Particularly, the biological activity and subsequent benefits of soy products may be associated with the presence of isoflavone in soybeans. As an alternative treatment for menopause-related symptoms, isoflavone has gained much popularity for postmenopausal women who have concerns related to undergoing hormone replacement therapy. However, current research has still not reached a consensus on the effects of isoflavone on humans. This overview is a summary of the current literature about the processing of soybeans and isoflavone types (daidzein, genistein, and S-equol) and supplements and their extraction and analysis as well as information about the utilization of isoflavones in soybeans. The processes of preparation (cleaning, drying, crushing and dehulling) and extraction of soybeans are implemented to produce refined soy oil, soy lecithin, free fatty acids, glycerol and soybean meal. The remaining components consist of inorganic constituents (minerals) and the minor components of biologically interesting small molecules. Regarding the preventive effects on diseases or cancers, a higher intake of isoflavones is associated with a moderately lower risk of developing coronary heart disease. It may also reduce the risks of breast and colorectal cancer as well as the incidence of breast cancer recurrence. Consumption of isoflavones or soy foods is associated with reduced risks of endometrial and bladder cancer. Regarding the therapeutic effects on menopausal syndrome or other diseases, isoflavones have been found to alleviate vasomotor syndromes even after considering placebo effects, reduce bone loss in the spine and ameliorate hypertension and in vitro glycemic control. They may also alleviate depressive symptoms during pregnancy. On the other hand, isoflavones have not shown definitive effects regarding improving cognition and urogenital symptoms. Because of lacking standardization in the study designs, such as the ingredients and doses of isoflavones and the durations and outcomes of trials, it currently remains difficult to draw overall conclusions for all aspects of isoflavones. These limitations warrant further investigations of isoflavone use for women's health.

Effect of a natural supplement containing glucosinolates, phytosterols and citrus flavonoids on body weight and metabolic parameters in a menopausal murine model induced by bilateral ovariectomy

OBJECTIVE

To evaluate the effect of a herbal preparation containing glucosinolates, phytosterols and citrus flavonoids (supplement) on body weight and metabolic parameters usually impaired by menopause.

METHODS

A pre-clinical experimental study carried out in twenty-five Swiss strain mice (Mus musculus) randomly distributed (1:1:1:1:1 ratio) to five groups to receive for ten weeks: (1) oral gelatinized maca extract 0.5625 mg/kg/day + bilateral ovariectomy (Maca + OVX); (2) oral supplement 0.5625 mg/kg/day + bilateral ovariectomy (S1 + OVX); (3) oral supplement 1.6875 mg/kg/day + bilateral ovariectomy (S2 + OVX); (4) oral saline 100 µl/kg/day + bilateral ovariectomy (OVX); and (5) oral saline 100 µl/kg/day + sham surgery (sham). The primary endpoint was change in body weight gain from baseline to final. Secondary endpoints were uterine weight and cholesterol, triglyceride, glucose, and glucose/triglycerides index values at the end of the study. A modified intention-to-treat analysis was performed through linear regression models and using the Bonferroni method to penalized p-values by multiple comparisons.

RESULTS

Twenty-three animals completed the study. There was a significant average difference in weight gain, with a greater reduction in the S2 + OVX group compared to the OVX group (difference= -3.5; 95% CI (-5.27; -1.74); p < .001). S2 + OVX group also displayed a significant average reduction of total blood cholesterol (difference: -16.94; 95% CI (-33.73; -0.15); p = .037). No significant effects of the supplement were found on other secondary endpoints.

CONCLUSION

In this murine menopausal model, triple oral supplement dose resulted in an average reduction of weight gain and total cholesterol levels, suggesting that the compound could have a potential effect at regulating menopausal altered metabolism.

Isoflavone Supplements for Menopausal Women: A Systematic Review

Isoflavones have gained popularity as an alternative treatment for menopausal symptoms for people who cannot or are unwilling to take hormone replacement therapy. However, there is still no consensus on the effects of isoflavones despite over two decades of vigorous research. This systematic review aims to summarize the current literature on isoflavone supplements, focusing on the active ingredients daidzein, genistein, and S-equol, and provide a framework to guide future research. We performed a literature search in Ovid Medline using the search terms “isoflavone” and “menopause”, which yielded 95 abstracts and 68 full-text articles. We found that isoflavones reduce hot flashes even accounting for placebo effect, attenuate lumbar spine bone mineral density (BMD) loss, show beneficial effects on systolic blood pressure during early menopause, and improve glycemic control in vitro. There are currently no conclusive benefits of isoflavones on urogenital symptoms and cognition. Due to the lack of standardized research protocols including isoflavone component and dosage, outcomes, and trial duration, it is difficult to reach a conclusion at this point in time. Despite these limitations, the evidence thus far favors the use of isoflavones due to their safety profile and benefit to overall health.

Comprehensive evaluation of the role of soy and isoflavone supplementation in humans and animals over the past two decades

Soy and soy-based foods are considered healthy, particularly in many Asia-Pacific countries, where soy products have long been consumed. Soy and soy-related products have been found to help prevent the occurrence of cardiovascular diseases and certain types of cancer, such as breast and prostate cancer. These products can also have antioxidative effects that alleviate hot flashes during menopause and bone loss. These biological and therapeutic functions are primarily due to the isoflavones derived from soy, whose structure is similar to the structure of 17-β-oestradiol. Despite the many health benefits for humans and animals, the application of isoflavones remains controversial because of their anti-oestrogenic properties. We focused on general information regarding isoflavones, as well as their structure, function, and application. We summarized evidence showing that dietary or supplemental isoflavones exert protective effects on the health of humans and animals. Based on the literature, we conclude that soy foods and isoflavones may be effective and safe; however, more high-quality trials are needed to fully substantiate their potential use.

Supercritical fluid chromatography for the separation of isoflavones

The first protocol for the analysis of isoflavones by supercritical fluid chromatography is reported. Optimum results were obtained on an Acquity UPC(2) BEH 1.7 μm column, using a solvent gradient of supercritical carbon dioxide and methanol (with phosphoric acid as additive) for elution. The method enables the baseline separation of nine isoflavones (aglyca and glycosides) in 8 min, and is suitable for their quantitative determination in dietary supplements containing soy (Glycine max), red glover (Trifolium pratense) and kudzu (Pueraria lobata). Method validation confirmed that the assay is selective, linear (R(2)≥0.9994), accurate (recovery rates from 97.6 to 102.4%), as well as precise on the short- and long-term level (intra-day precision ≤2.1%), and shows an on-column detection limit of 0.2 ng and below. This, together with an excellent performance shown in the analysis of real samples, indicates that SFC is well suited for the fast and accurate determination of isoflavones in complex matrices. Disadvantages compared to the established approaches were not observed, so that SFC has to be considered in this case as an (at least) equivalent analytical alternative.

Soy isoflavones have antimutagenic activity on DNA damage induced by the antileishmanial Glucantime (meglumine antimoniate)

Isoflavones are phytoestrogens reported to be potent antioxidant agents. In contrast, the antileishmanial meglumine antimoniate has mutagenic activities. This study evaluated the ability of soy isoflavones to reduce DNA damage induced by meglumine antimoniate. Antimutagenic effects (by micronucleus test) were tested using Swiss mice divided into seven groups treated with meglumine antimoniate (425 mg/kg bw pentavalent antimony); cyclophosphamide (50 mg/kg bw); water (negative control); single isoflavones dose (1.6 mg/kg bw), and three groups received one dose of isoflavones via gavage (0.4 mg/kg bw, 0.8 mg/kg bw or 1.6 mg/kg bw) plus meglumine antimoniate via intraperitoneal, simultaneously. To evaluate antigenotoxicity (by Comet assay), each group with 10 animals received the above-mentioned control doses; single dose of isoflavones 0.8 mg/kg bw, and three groups received isoflavones (0.8 mg/kg bw) by gavage along with intraperitoneal meglumine antimoniate, which were treated with isoflavones 24 h before or after receiving meglumine antimoniate (pre-treatment and post-treatment, respectively) or simultaneously. Cells were harvested 24 h after the treatment, and the data were evaluated by ANOVA followed by Tukey's test (p < 0.05). The data from the simultaneous treatment by micronucleus test revealed that isoflavones (0.4 and 0.8 mg/kg) were able to reverse the mutagenic effect of Glucantime. Moreover, all regimes of the treatment with 0.8 mg/kg bw dose were able to reduce the genotoxicity caused by meglumine antimoniate. It is suggested that the protective effect of isoflavones against DNA damage is related to their ability to reduce oxidative stress caused by the trivalent Sb(III) metabolite of meglumine antimoniate.

Phytoestrogens as alternative hormone replacement therapy in menopause: What is real, what is unknown

Menopause is characterized by an altered hormonal status and by a decrease in life quality due to the appearance of uncomfortable symptoms. Nowadays, with increasing life span, women spend one-third of their lifetime under menopause. Understanding menopause-associated pathophysiology and developing new strategies to improve the treatment of menopausal-associated symptoms is an important topic in the clinic. This review describes physiological and hormone alterations observed during menopause and therapeutic strategies used during this period. We critically address the benefits and doubts associated with estrogen/progesterone-based hormone replacement therapy (HRT) and discuss the use of phytoestrogens (PEs) as a possible alternative. These relevant plant-derived compounds have structural similarities to estradiol, interacting with cell proteins and organelles, presenting several advantages and disadvantages versus traditional HRT in the context of menopause. However, a better assessment of PEs safety/efficacy would warrant a possible widespread clinical use.

The pros and cons of plant estrogens for menopause

Concerns pertaining to the risk of estrogen exposure through HT have prompted an increase in the use of natural alternatives. Phytoestrogens may provide postmenopausal women with a practical alternative and many women have already begun to utilize phytoestrogen supplements. However, research regarding the efficacy of phytoestrogens as a hormone therapy alternative has been previously pessimistic or questionable at best. This review scrutinizes the most current research regarding the efficacy of three types of phytoestrogens, isoflavones, lignans and coumestans, and their specific effect on the reduction of climacteric symptoms, specifically vasomotor symptoms, vaginal atrophy, insomnia and osteoporosis. A discussion of the research pertaining to the relative safety of each phytoestrogen in terms of breast and endometrial health is also included. Overall, current research demonstrates that phytoestrogens are effective in reducing the intensity of hot flushes, and some phytoestrogen combinations result in a decreased frequency. Certain phytoestrogens have also been shown to decrease vaginal atrophy, improve sleep and cognition, and positively affect bone health. Even though initial research was generally unconvincing, the more recent evidence reviewed here is rather positive. In terms of safety and reports of adverse reactions, trials have not shown an increase in breast cancer risk or increase in endometrial hyperplasia following phytoestrogen use, but trials explicitly designed to find neoplasia have not been reported. Moreover, unlike hormone therapy, lignans may not increase clotting risk in postmenopausal women, thus supplements may serve as a treatment option for patients who have contraindications to hormone therapy. Phytoestrogens may provide a safe and partially effective alternative to HT. However, because research regarding phytoestrogens is relatively new, pharmaco-vigilence is still required, as these products are not yet FDA-approved. This article is part of a Special Issue entitled 'Phytoestrogens'.