Effect of soy protein containing isoflavones on endothelial and vascular function in postmenopausal women: a systematic review and meta-analysis of randomized controlled trials

Perspective: Isoflavones-Intriguing Molecules but Much Remains to Be Learned about These Soybean Constituents

Isoflavones are naturally occurring compounds found in a wide range of plants, but among commonly consumed foods are especially abundant in soybeans and foods derived from this legume. Much of the substantial amount of research conducted on soy protein and soy foods over the past 30 y is because of their isoflavone content. Research interest in isoflavones increased dramatically beginning in the early 1990s as evidence highlighted their possible role in the prevention of a wide range of cancers, including breast, prostate, and colon cancer. Recognition that isoflavones preferentially bind to estrogen receptor (ER)β in comparison with ERα provided a conceptual basis for classifying these diphenolic molecules as selective ER modulators (SERMs). Isoflavone research soon greatly expanded beyond cancer to include areas such as coronary artery disease, bone health, cognitive function, and vasomotor symptoms of menopause. Nevertheless, safety concerns about isoflavones, based primarily on the results of rodent studies and presumed estrogenic effects, also arose. However, recent work challenges the traditional view of the estrogenicity of isoflavones. Furthermore, safety concerns have largely been refuted by intervention and population studies. On the other hand, investigation of the proposed benefits of isoflavones has produced inconsistent data. The small sample size and short duration common to many intervention trials, combined with marked interindividual differences in isoflavone metabolism, likely contribute to the conflicting findings. Also, many different intervention products have been employed, which vary not only in the total amount, but also in the relative proportion of the 3 soybean isoflavones, and the form in which they are delivered (glycoside compared with aglycone). For those interested in exploring the proposed benefits of isoflavones, studies justify an intake recommendation of ∼50 mg/d, an amount provided by ∼2 servings of traditional Asian soy foods.

An Updated Review Summarizing the Pharmaceutical Efficacy of Genistein and its Nanoformulations in Ovarian Carcinoma

Implementing lifestyle interventions as a primary prevention strategy is a cost-effective approach to reducing the occurrence of cancer, which is a significant contributor to illness and death globally. Recent advanced studies have uncovered the crucial role of nutrients in safeguarding women's health and preventing disorders. Genistein is an abundant isoflavonoid found in soybeans. Genistein functions as a chemotherapeutic drug against various forms of cancer, primarily by modifying apoptosis, the cell cycle, and angiogenesis and suppressing metastasis. Furthermore, Genistein has demonstrated diverse outcomes in women, contingent upon their physiological characteristics, such as being in the early or postmenopausal stages. The primary categories of gynecologic cancers are cervical, ovarian, uterine, vaginal, and vulvar cancers. Understanding the precise mechanism by which Genistein acts on ovarian cancer could contribute to the advancement of anti-breast cancer treatments, particularly in situations where no specific targeted therapies are currently known or accessible. Additional investigation into the molecular action of Genistein has the potential to facilitate the development of a plant-derived cancer medication that has fewer harmful effects. This research could also help overcome drug resistance and prevent the occurrence of ovarian cancers.

Functional Foods and Nutraceuticals for the Management of Cardiovascular Disease Risk in Postmenopausal Women

Cardiovascular disease (CVD) is a leading cause of death in women and risk of development is greatly increased following menopause. Menopause occurs over several years and is associated with hormonal changes, including a reduction in estradiol and an increase in follicle-stimulating hormone. This hormonal shift may result in an increased risk of developing abdominal adiposity, insulin resistance, dyslipidemia, vascular dysfunction, hypertension, type 2 diabetes mellitus (T2DM), metabolic dysfunction-associated fatty liver disease (MAFLD), and metabolic syndrome (MetS). Furthermore, with the onset of menopause, there is an increase in oxidative stress that is associated with impaired vascular function, inflammation, and thrombosis, further increasing the risk of CVD development. Despite the harmful consequences of the menopause transition being well known, women in premenopausal, perimenopausal, and postmenopausal stages are unlikely to be enrolled in research studies. Therefore, investigations on the prevention and treatment of cardiovascular and metabolic disease in middle-aged women are still relatively limited. Whilst lifestyle interventions are associated with reduced CVD risk in this population sample, the evidence still remains inconclusive. Therefore, it is important to explore the effectiveness of early intervention and potential therapeutic approaches to maintain cellular redox balance, preserve endothelium, and reduce inflammation. Glycine, N-acetylcysteine, and L-theanine are amino acids with potential antioxidant and anti-inflammatory activity and are identified as therapeutic interventions in the management of age-related and metabolic diseases. The benefits of the intake of these amino acids for improving factors associated with cardiovascular health are discussed in this review. Future studies using these amino acids are warranted to investigate their effect on maintaining the vascular health and cardiovascular outcomes of postmenopausal women.

Crosstalk between ethylene and melatonin activates isoflavone biosynthesis and antioxidant systems to produce high-quality soybean sprouts

Isoflavone, which are mainly found in soybeans, are a secondary metabolite with a variety of physiological functions. In recent years, increasing the isoflavone content of soybeans has received widespread attention. Although ethephon treatment significantly increased isoflavone content in soybean sprouts, it also had a certain inhibitory effect on the growth of sprouts. Melatonin (MT), as a new type of plant hormone, not only alleviated the damage caused by abiotic stress to plants, but also promoted the synthesis of secondary metabolites. In this study, we aimed to elucidate the mechanism of exogenous MT in regulating the growth and development, and the metabolism of isoflavone in soybean sprouts under ethephon treatment. The results indicated that MT alleviated the adverse effects of ethephon treatment on soybean sprouts by increasing the activities of superoxide dismutase, peroxidase, catalase, and the expression of their corresponding genes, as well as decreased the content of malondialdehyde and hydrogen peroxide. In addition, MT further increased the isoflavone content by up-regulating the expression level of isoflavone synthesis genes and increased the activities of phenylalanine ammonia-lyase and cinnamic acid 4-hydroxylase under ethephon treatment. This study provided technical support and reference value for the production of high-quality soybean sprouts to a certain extent.

Daily blueberry consumption for 12 weeks improves endothelial function in postmenopausal women with above-normal blood pressure through reductions in oxidative stress: a randomized controlled trial

Estrogen-deficient postmenopausal women have oxidative stress-mediated suppression of endothelial function that is exacerbated by high blood pressure. Previous research suggests blueberries may improve endothelial function through reductions in oxidative stress, while also exerting other cardiovascular benefits. The objective of this study was to examine the efficacy of blueberries to improve endothelial function and blood pressure in postmenopausal women with above-normal blood pressure, and to identify potential mechanisms for improvements in endothelial function. A randomized, double-blind, placebo-controlled, parallel-arm clinical trial was performed, where postmenopausal women aged 45-65 years with elevated blood pressure or stage 1-hypertension (total n = 43, endothelial function n = 32) consumed 22 g day^-1 of freeze-dried highbush blueberry powder or placebo powder for 12 weeks. Endothelial function was assessed at baseline and 12 weeks through ultrasound measurement of brachial artery flow-mediated dilation (FMD) normalized to shear rate area under the curve (FMD/SR_AUC) before and after intravenous infusion of a supraphysiologic dose of ascorbic acid to evaluate whether FMD improvements were mediated by reduced oxidative stress. Hemodynamics, arterial stiffness, cardiometabolic blood biomarkers, and plasma (poly)phenol metabolites were assessed at baseline and 4, 8, and 12 weeks, and venous endothelial cell protein expression was assessed at baseline and 12 weeks. Absolute FMD/SR_AUC was 96% higher following blueberry consumption compared to baseline (p < 0.05) but unchanged in the placebo group (p > 0.05), and changes from baseline to 12 weeks were greater in the blueberry group than placebo (+1.09 × 10^-4 ± 4.12 × 10^-5vs. +3.82 × 10^-6 ± 1.59 × 10^-5, p < 0.03, respectively). The FMD/SR_AUC response to ascorbic acid infusion was lower (p < 0.05) at 12 weeks compared to baseline in the blueberry group with no change in the placebo group (p > 0.05). The sum of plasma (poly)phenol metabolites increased at 4, 8, and 12 weeks in the blueberry group compared to baseline, and were higher than the placebo group (all p < 0.05). Increases in several plasma flavonoid and microbial metabolites were also noted. No major differences were found for blood pressure, arterial stiffness, blood biomarkers, or endothelial cell protein expression following blueberry consumption. These findings suggest daily consumption of freeze-dried blueberry powder for 12 weeks improves endothelial function through reduced oxidative stress in postmenopausal women with above-normal blood pressure. The clinical trial registry number is NCT03370991 (https://clinicaltrials.gov).

Combined Orobol-Bentonite Composite Formulation for Effective Topical Skin Targeted Therapy in Mouse Model

Purpose

Orobol is an isoflavone that has a potent skin protection effect. The objective of this study was to prepare a novel bentonite-based composite formulation of orobol to enhance topical skin delivery.

Methods

The composition was optimized based on the orobol content in the composite and the in vitro release studies, followed by the in vitro and in vivo hairless mouse skin deposition studies. Physicochemical characterizations of the composite formulation were performed by powder X-ray refractometry (XRD) and scanning electron microscopy (SEM). The in vitro cytotoxicity and in vivo toxicity studies were conducted in human keratinocytes and in hairless mouse, respectively.

Results and Discussions

The in vitro release of orobol from the bentonite composites was higher than that from the suspension, which was further increased with the addition of phosphatidylcholine. The composite formulation significantly enhanced the in vitro and in vivo skin deposition of orobol in hairless mouse skin compared to the orobol suspension. Moreover, the addition of phosphatidyl choline not only improved the dissolution and incomplete release of orobol from the bentonite composite but also enhanced the deposition of orobol in the skin. XRD histograms and SEM images confirmed that the enhanced dissolution of orobol from the composite was attributed to its amorphous state on bentonite. The in vitro and in vivo toxicity studies support the safety and biocompatibility of the orobol-loaded bentonite composite formulation.

Conclusion

These findings suggest that the orobol-loaded bentonite composite formulation could be a potential topical skin delivery system for orobol.

Protective effect of isoflavone enriched soy β-conglycinin on osteoporosis in ovariectomized rats

Research shows that the consumption of soybean foods can reduce the incidence rate of bone fractures in women after menopause. The aim of this study was to investigate the effects of different complex of soy β-conglycinin (7S) and isoflavones (7S-ISO) on osteoporosis in ovariectomized rats. All treatments were administrated intragastrically to the groups every afternoon for 3 months. The treatments were administrated at 1 mL·(100 g)^-1 , the animals were given 50 mg·kg^-1 ·d^-1 ISO, and the concentration of protein was about 2 wt. %. The bone mineral density (BMD) and the bone biomechanics results of left tibia' maximum load in the 7S-ISO group is significantly higher than in the ovariectomized group and the 7S group (p < .05). Otherwise, the serum tartrate-resistant acid phosphatase (s-TRACP), serum osteocalcin (s-BGP), and serum estradiol (s-E₂ ) levels in 7S-ISO were all significantly different from the OVX, OVX + casein, and the OVX + 7S group (p < .05). The serum calcium (s-Ca) level was not significantly different among all the groups. 7S-ISO may exhibit moderate estrogenic activities and as compared to 7S and ISO in osteoporosis (OP) of ovariectomized rats. PRACTICAL APPLICATIONS: The effects of soy proteins on the health of females have always been a concern. It has been extensively reported soy 7S globulin (7S) as a type of trimer glycoprotein can depress blood fats. The aim of this study was to investigate the effects of different complex of soy β-conglycinin and isoflavones (ISO), the main storage proteins and polyphenols in soy, on osteoporosis in ovariectomized rats.

Scientific Evidence Supporting the Beneficial Effects of Isoflavones on Human Health

Isoflavones are phenolic compounds with a chemical structure similar to that of estradiol. They are present in several vegetables, mainly in legumes such as soy, white and red clover, alfalfa and beans. The most significant food source of isoflavones in humans is soy-derived products. Isoflavones could be used as an alternative therapy for pathologies dependent on hormonal disorders such as breast and prostate cancer, cardiovascular diseases, as well as to minimize menopausal symptoms. According to the results gathered in the present review, it can be stated that there is scientific evidence showing the beneficial effect of isoflavones on bone health and thus in the prevention and treatment of osteoporosis on postmenopausal women, although the results do not seem entirely conclusive as there are discrepancies among the studies, probably related to their experimental designs. For this reason, the results should be interpreted with caution, and more randomized clinical trials are required. By contrast, it seems that soy isoflavones do not lead to a meaningful protective effect on cardiovascular risk. Regarding cancer, scientific evidence suggests that isoflavones could be useful in reducing the risk of suffering some types of cancer, such as breast and endometrial cancer, but further studies are needed to confirm these results. Finally, isoflavones could be useful in reducing hot flushes associated with menopause. However, a limitation in this field is that there is still a great heterogeneity among studies. Lastly, with regard to isoflavone consumption safety, it seems that they are safe and that the most common adverse effect is mild and occurs at the gastrointestinal level.