Soy protein, soybean isoflavones and coronary heart disease risk: where do we stand?

A molecular genetics view on Mucopolysaccharidosis Type II

Mucopolysaccharidosis Type II (MPS II) is an X-linked recessive genetic disorder that primarily affects male patients. With an incidence of 1 in 100,000 male live births, the disease is one of the orphan diseases. MPS II symptoms are caused by mutations in the lysosomal iduronate-2-sulfatase (IDS) gene. The mutations cause a loss of enzymatic performance and result in the accumulation of glycosaminoglycans (GAGs), heparan sulfate and dermatan sulfate, which are no longer degradable. This inadvertent accumulation causes damage in multiple organs and leads either to a severe neurological course or to an attenuated course of the disease, although the exact relationship between mutation, extent of GAG accumulation and disease progression is not yet fully understood. This review is intended to present current diagnostic procedures and therapeutic interventions. In times when the genetic profile of patients plays an increasingly important role in the assessment of therapeutic success and future drug design, we chose to further elucidate the impact of genetic diversity within the IDS gene on disease phenotype and potential implications in current diagnosis, prognosis and therapy. We report recent advances in the structural biological elucidation of I2S enzyme that that promises to improve our future understanding of the molecular damage of the hundreds of IDS gene variants and will aid damage prediction of novel mutations in the future.

Effect of soybean milk fermented with Lactobacillus plantarum HFY01 isolated from yak yogurt on weight loss and lipid reduction in mice with obesity induced by a high-fat diet

Soybean milk fermented with Lactobacillus plantarum HFY01 (LP-HFY01) was used for weight and lipid reduction in mice with obesity induced by a high-fat diet. We evaluated the gastrointestinal tolerance in vitro, organ index, body fat rate, pathological changes, serum index, mRNA expression and changes of isoflavones in soybean milk. Results indicated that LP-HFY01 exhibited good tolerance to pH 3.0 artificial gastric juice (69.87 ± 0.04%) and 0.3% bile salt (15.94 ± 0.3%). LP-HFY01-fermented soybean milk reduced the body fat rate and liver index of obese mice (p < 0.05). Organ sections showed that LP-HFY01-fermented soybean milk improved fatty degeneration and liver cell damage caused by a high-fat diet. LP-HFY01-fermented soybean milk inhibited increases in low-density lipoprotein cholesterol (LDL-c), triglyceride (TG), alkaline phosphatase (AKP), and glutamic oxaloacetic transaminase (GOT) and the decrease in high-density lipoprotein cholesterol (HDL-c) in the serum of obese mice, and inhibited CCAAT/enhancer-binding protein-α (C/EBP-α) and peroxisome proliferator-activated receptor-γ (PPAR-γ) mRNA expression, as well as activated cuprozinc-superoxide dismutase (SOD1) and lipoprotein lipase (LPL) mRNA expression in the liver and epididymal fat of obese mice (p < 0.05). Daidzin, glycitin, daidzein, glycitein, genistein, and genistin contents in soybean milk were determined before and after fermentation by high-performance liquid chromatography (HPLC); the daidzin and genistin contents in the fermented soybean milk decreased, whereas the daidzein and genistein contents increased significantly. Therefore, the LP-HFY01-fermented soybean milk strongly inhibits obesity induced by a high-fat diet, and shows good potential for utilization.

Biofortification of pulses and legumes to enhance nutrition

Pulses and legumes belong to the Fabaceae family which are nutritionally rich especially chickpeas, mungbeans, soybeans, and peas. Pulses and legumes are important source of plant protein in many diets. They are also an excellent reservoir of dietary fiber and complex carbohydrates resulting in low GI (glycemic index). Pulses play vital role in metabolic and physiological processes due to the presence of various bioactive compounds, and the majority of them are phenolic acids, flavonoids, and tannins. Pulses and legumes are also a good source of 15 essential minerals and vitamins, but their bioavailability is low due to the presence of antinutrient factors in it. Biofortification is a method by which the nutritional value of pulses and legumes can be increased with the help of breeding, transgenic techniques, or agronomic practices and thus helps in preventing the malnutrition. In view of these details, pulses and legumes provide immense opportunities for its inclusion in manufacturing snacks and sports foods.

Talinum triangulare Whole wheat meal fortified with soy flour consumed with Talinum triangulare (gbure) soup glycemic index and the test human subjects' lipid profiles

AIM

Cardiovascular diseases (CVDs) and diabetes mellitus (DM) are some of the leading causes of death in the world, and diet has roles in their etiology. This research study therefore investigates the glycemic index (GI) of soy flour fortified whole wheat meal (SFFWWM) consumed with Talinum triangulare (gbure) soup and the effects of the meal on the lipid profiles of the test human subjects.

METHODS

The control human subjects and test human subjects were fed D-glucose (DG) and whole wheat meal (WWM) with Talinum triangulare soup respectively on the first day of the experiment, and SFFWWM with the same soup the next day (for test subjects only) after 10-12h overnight fasting. Blood glucose levels of the subjects were taken before and 2h after meals' consumption at 30min interval and blood samples collected for lipid profiles evaluations.

RESULTS

The result of the study showed that; SFFWWM consumed with Talinum trianguilare soup has a non-significant lower GI than WWM consumed with the same soup, but a significant lower GI than DG at (P<0.05). Furthermore, there was no significant difference in lipid profiles of the test human subjects between when they consumed WWM and SFFWWM with the soup however, SFFWWM reduced TC, TG, LDL-C and VDL-C and increased HDL-C and TP than WMM at (P<0.05). In addition, GI is positively correlated with TC, TG, LDL-C and VLDL-C, but is negatively correlated with TP and HDL-C.

CONCLUSION

It can therefore be concluded that; fortifying WWM with soy flour would reduce the risk factors of CVDs and DM, the diseases recently claiming thousands of today.

Multigene synergism increases the isoflavone and proanthocyanidin contents of Medicago truncatula

Isoflavones and proanthocyanidins (PAs), which are flavonoid derivatives, possess many health benefits and play important roles in forage-based livestock production. However, the foliage of Medicago species accumulates limited levels of both isoflavones and PAs. In this study, biosynthesis of isoflavone and PA in Medicago truncatula was enhanced via synergy between soya bean isoflavone synthase (IFS1); two upstream enzymes, chalcone synthase (CHS) and chalcone isomerase (CHI); and the endogenous flavanone 3-hydroxylase (F3H). Constitutive expression of GmIFS1 alone resulted in ectopic accumulation of the isoflavone daidzein and large increases in the levels of the isoflavones formononetin, genistein and biochanin A in the leaves. Furthermore, coexpression of GmIFS1 with GmCHS7 and GmCHI1A generally increased the available flux to flavonoid biosynthesis and resulted in elevated isoflavone, flavone and PA contents. In addition, down-regulation of MtF3H combined with coexpression of GmIFS1, GmCHS7 and GmCHI1A led to the highest isoflavone levels (up to 2 μmol/g fresh weight in total). Taken together, our results demonstrate that multigene synergism is a powerful means to enhance the biosynthesis of particular flavonoids and can be more broadly applied to the metabolic engineering of forage species.

Effect of protein source during weight loss on body composition, cardiometabolic risk and physical performance in abdominally obese, older adults: a pilot feeding study

OBJECTIVES

The purpose of this pilot study was to begin to examine the effect of dietary protein source (soy protein versus non-soy protein) during weight loss on body composition, and cardiometabolic and functional decline risk factors in older, abdominally obese adults.

DESIGN

Two-arm, single-blind, randomized, controlled trial.

SETTING

Wake Forest School of Medicine, Winston-Salem NC 27157, USA.

PARTICIPANTS

25 older (68.4±5.5 years, 88% female), abdominally obese (BMI: 35.1±4.3 kg/m2; WC: 101.4±13.1 cm) men and women were randomized to participate in the study.

INTERVENTION

A 12-week weight loss intervention, with participants randomized to consume soy protein-based meal replacements (S; n=12) or non-soy protein-based meal replacements (NS; n=12), in addition to prepared meals, and all participants targeted to receive an individualized caloric deficit of 500 kcal/day.

MEASUREMENTS

Body weight and composition (assessed via DXA and CT), conventional biomarkers of cardiometabolic risk, and physical performance measures were assessed pre- and post-intervention. Additional endpoints of feasibility (accrual, participation, retention, compliance, and safety) are reported.

RESULTS

A total of 24 participants (87% female) completed the study (96% retention) and lost an average of 7.8±3.0 kg over the 12-week period, with no difference seen between groups (p=0.83). Although nearly all measures of global and regional body composition were significantly reduced following the 12-week intervention, differences were not observed between groups. Among cardiometabolic risk factors and physical performance measures, only diastolic blood pressure was significantly lower in the NS group compared to the S group (66.7±2.7 mmHg vs 73.5±2.7 mmHg, respectively; p=0.04). Interestingly, in groups combined, despite significant reductions in body weight and lean mass, no significant changes in 400-meter walk time (+5.3±43.4 s), short physical performance battery score (+0.1±1.0), grip strength (-0.3±3.2 kg), or relative knee extensor strength (-0.0±0.0 N/m/cm3 thigh muscle volume) were observed.

CONCLUSIONS

Data presented here suggest that a 12-week weight loss intervention, which incorporates S and NS meal replacement products, is associated with clinically significant weight loss and improvements in several parameters of cardiometabolic risk and unchanged physical function and strength. RESULTS do not differ by protein source and suggest that soy protein is at least as good as other protein sources for weight loss during low-calorie dietary interventions in older adults.

Metabolic studies of four soy isoflavones in rats by HPLC-HR-MS

In this paper, the metabolites of four soy isoflavones, daidzein, daidzin, genistein, and genistin, on perfused rat intestine-liver model were investigated by high-performance liquid chromatography coupled with high-resolution mass spectrometer/tandem mass spectrometer. Totally 16 metabolites were detected and identified based on accurate mass, fragmentation patterns, and multiple-stage mass data (MS(n)). The metabolic site of dadzein-7-methyl ether (D-7-M) was further confirmed by nuclear magnetic resonance. Methylation, glucuronide conjugation, and sulfate conjugation were the primary metabolic processes. Among them, six metabolites, daidzin-4',7-diglucoside, genistein-4'-glucoside, D-7-M, dadzein-4',7-dimethyl ether, genistein-4'-methyl ether, and genistein-7-methyl ether were detected in rats for the first time and not reported in humans. The metabolic pathways of daidzein, daidzin genistein, and genistin in rats were postulated. The biological effects of these metabolites are worthy of further investigation.

Soy isoflavone phase II metabolism differs between rodents and humans: implications for the effect on breast cancer risk

BACKGROUND

Human and animal studies have produced conflicting results with regard to the effect of soy isoflavones on breast cancer risk. This may be due to differences in isoflavone metabolism.

OBJECTIVE

The objective of this study was to determine whether soy isoflavone phase II metabolism differs between humans and rodents.

DESIGN

Circulating total and unconjugated isoflavone concentrations were determined by mass spectrometry in plasma samples from 7 separate studies: 1) in Sprague-Dawley rats and in 3 strains of mice fed commercial soy-containing diets; 2) in Sprague-Dawley rats gavaged with genistein; 3) in healthy adults who consumed single servings of soy nuts, soy milk, and tempeh; 4) in healthy adults subchronically given soy milk; 5) in healthy women orally administered 50 mg genistein; 6) in healthy women orally administered 20 mg pure S-(-)equol; and 7) in 6-mo-old infants fed soy infant formula and later, at age 3 y, a soy germ isoflavone supplement.

RESULTS

The proportion of unconjugated genistein in plasma from adults and infants who consumed different soy foods, pure genistein, or an isoflavone supplement was <1% in steady state and <2% at peak concentrations. By contrast, rodents fed soy-containing diets conjugate isoflavones less efficiently. The plasma percentages of unconjugated genistein concentrations in Sprague-Dawley rats and C57BL/6, nude, and transgenic AngptL4B6 mice were 4.0 ± 0.6%, 4.6 ± 0.6%, 11.6 ± 0%, and 30.1 ± 4.3%, respectively, which represent 20, 23, 58, and 150 times that in humans.

CONCLUSION

The markedly higher circulating concentrations of biologically active (unconjugated) genistein in certain strains of mice cast doubt on the value of the use of these rodents for gaining insight into the effects of isoflavones in humans, especially with regard to the effects on breast tissue.

Hypogonadism and erectile dysfunction associated with soy product consumption

Previous research has focused on the beneficial effects of soy and its active ingredients, isoflavones. For instance, soy consumption has been associated with lower cardiovascular and breast cancer risks. However, the number of reports demonstrating adverse effects of isoflavones due to their estrogenlike properties has increased. We present the case of a 19-y-old type 1 diabetic but otherwise healthy man with sudden onset of loss of libido and erectile dysfunction after the ingestion of large quantities of soy-based products in a vegan-style diet. Blood levels of free and total testosterone and dehydroepiandrosterone (DHEA) were taken at the initial presentation for examination and continuously monitored up to 2 y after discontinuation of the vegan diet. Blood concentrations of free and total testosterone were initially decreased, whereas DHEA was increased. These parameters normalized within 1 y after cessation of the vegan diet. Normalization of testosterone and DHEA levels was paralleled by a constant improvement of symptoms; full sexual function was regained 1 y after cessation of the vegan diet. This case indicates that soy product consumption is related to hypogonadism and erectile dysfunction. To the best of our knowledge, this is the first report of a combination of decreased free testosterone and increased DHEA blood concentrations after consuming a soy-rich diet. Hence, this case emphasizes the impact of isoflavones in the regulation of sex hormones and associated physical alterations.

Insights gained from 20 years of soy research

Soyfoods have long been recognized for their high-protein and low-saturated fat content, but over the past 20 y an impressive amount of soy-related research has evaluated the role of these foods in reducing chronic disease risk. Much of this research has been undertaken because the soybean is essentially a unique dietary source of isoflavones, a group of chemicals classified as phytoestrogens. The estrogen-like properties of isoflavones have also raised concern, however, that soyfoods might exert adverse effects in some individuals. There is intriguing animal and epidemiologic evidence indicating that modest amounts of soy consumed during childhood and/or adolescence reduces breast cancer risk. Evidence also suggests that soy reduces prostate cancer risk and inhibits prostate tumor metastasis, but additional clinical support for the chemopreventive effects of soyfoods is needed. Soy protein is modestly hypocholesterolemic and there is suggestive epidemiologic evidence that soyfoods lower risk of coronary heart disease (CHD) independent of effects on cholesterol. In clinical studies, soy favorably affects multiple CHD risk factors; however, with the exception of improved endothelial function, the data are too limited and/or inconsistent to allow definitive conclusions to be made. In regard to bone health, although recent clinical data have not supported the skeletal benefits of isoflavones, 2 large prospective epidemiologic studies found soy intake is associated with marked reductions in fracture risk. Soybean isoflavones also modestly alleviate hot flashes in menopausal women. Finally, other than allergic reactions, there is almost no credible evidence to suggest traditional soyfoods exert clinically relevant adverse effects in healthy individuals when consumed in amounts consistent with Asian intake.

The role of soy in vegetarian diets

Soyfoods have long been prized among vegetarians for both their high protein content and versatility. Soybeans differ markedly in macronutrient content from other legumes, being much higher in fat and protein, and lower in carbohydrate. In recent years however, soyfoods and specific soybean constituents, especially isoflavones, have been the subject of an impressive amount of research. Nearly 2,000 soy-related papers are published annually. This research has focused primarily on the benefits that soyfoods may provide independent of their nutrient content. There is particular interest in the role that soyfoods have in reducing risk of heart disease, osteoporosis and certain forms of cancer. However, the estrogen-like effects of isoflavones observed in animal studies have also raised concerns about potential harmful effects of soyfood consumption. This review addresses questions related to soy and chronic disease risk, provides recommendations for optimal intakes, and discusses potential contraindications. As reviewed, the evidence indicates that, with the exception of those individuals allergic to soy protein, soyfoods can play a beneficial role in the diets of vegetarians. Concerns about adverse effects are not supported by the clinical or epidemiologic literature. Based on the soy intake associated with health benefits in the epidemiologic studies and the benefits noted in clinical trials, optimal adult soy intake would appear to be between two and four servings per day.

A brief historical overview of the past two decades of soy and isoflavone research

During the past 20 years, a remarkable amount of research into the health effects of soy consumption has been conducted, which in large part can be attributed to the presence of isoflavones in the soybean. Isoflavones first came to the attention of the scientific community in the 1940s because of fertility problems observed in sheep grazing on a type of isoflavone-rich clover. In the 1950s, as a result of their estrogenic effects in rodents, isoflavones were studied as possible growth promoters for use by the animal feed industry, although shortly thereafter, it was shown that isoflavones could also function as antiestrogens. Despite this early work, it was not until the 1990s, largely because of research sponsored by the U.S. National Cancer Institute, that the role of soyfoods in disease prevention began to receive widespread attention. Subsequently, isoflavones and soyfoods were being studied for their ability to alleviate hot flashes and inhibit bone loss in postmenopausal women. In 1995, soy protein attracted worldwide attention for its ability to lower cholesterol. At this same time, isoflavones began to be widely discussed as potential alternatives to conventional hormone therapy. In 2002, it was hypothesized that individuals possessing the intestinal bacteria capable of converting the soybean isoflavone daidzein into the isoflavan equol were more likely to benefit from soy intake. More recently, in vitro and animal research has raised questions about the safety of isoflavone exposure for certain subsets of the population, although the human data are largely inconsistent with these concerns.

Isoflavones and antioxidant capacity of commercial soy-based beverages: effect of storage

Samples of 11 different brands of commercially available soy-based beverages (n = 65), including products made from soy protein isolate (SPI) and soy milk, mixed with fruit juice and/or flavoring, were analyzed for their isoflavone content and in vitro antioxidant activity. There was a large variation in isoflavone and total phenolics contents ranging from 0.7 to 13 mg of isoflavones/200 mL and from 6 to 155 mg equivalents of catechin/200 mL, respectively. The antioxidant activity also varied significantly among products. Storage of the beverages at room temperature caused a significant decrease of antioxidant capacity, soluble phenolics, and isoflavone contents after 9 months. When soybeans used for beverage production were stored for up to 6 months in silos, the resulting products were not affected. However, a decrease of malonyl and a proportional increase of free glucosidic forms of isoflavones were observed after storage of both the raw material and the beverages.

Soy consumption, adhesion molecules, and pro-inflammatory cytokines: a brief review of the literature

Given the interest in the vascular effects of both soyfoods and soy isoflavones, the purpose of this short review is to evaluate clinical trials that have examined the effects of isoflavone-rich soy products on the novel cardiovascular risk factors, cellular adhesion molecules, and pro-inflammatory cytokines. A total of 14 randomized clinical studies were assessed. From the data evaluated, evidence suggests that neither soyfoods nor soy isoflavones affect IL-6 or TNF-alpha expression. In contrast, the effects of soy on cellular adhesion molecules are mixed. Study design characteristics possibly contributing to the inconsistent data are discussed and recommendations for future research in this area are presented.

Soybeans as a phytochemical reservoir for the production and stabilization of biocompatible gold nanoparticles

The present study demonstrates an unprecedented green process for the production of gold nanoparticles by simple treatment of gold salts with soybean extracts. Reduction capabilities of antioxidant phytochemicals present in soybean and their ability to reduce gold salts chemically to nanoparticles with subsequent coating of proteins and a host of other phytochemicals present in soybean on the freshly generated gold nanoparticles are discussed. The new genre of green nanoparticles exhibit remarkable in vitro stability in various buffers including saline, histidine, HSA, and cysteine solutions. MTT assays reveal that the green gold nanoparticles are nontoxic and thus provide excellent opportunities for their applications in nanomedicine for molecular imaging and therapy. The overall strategy described herein for the generation of gold nanoparticles meets all 12 principles of green chemistry, as no "man-made" chemicals, other than the gold salts, are used in the green nanotechnological process.