Soy β-conglycinin improves obesity-induced metabolic abnormalities in a rat model of nonalcoholic fatty liver disease

The Beneficial Effects of Soybean Proteins and Peptides on Chronic Diseases

With lifestyle changes, chronic diseases have become a public health problem worldwide, causing a huge burden on the global economy. Risk factors associated with chronic diseases mainly include abdominal obesity, insulin resistance, hypertension, dyslipidemia, elevated triglycerides, cancer, and other characteristics. Plant-sourced proteins have received more and more attention in the treatment and prevention of chronic diseases in recent years. Soybean is a low-cost, high-quality protein resource that contains 40% protein. Soybean peptides have been widely studied in the regulation of chronic diseases. In this review, the structure, function, absorption, and metabolism of soybean peptides are introduced briefly. The regulatory effects of soybean peptides on a few main chronic diseases were also reviewed, including obesity, diabetes mellitus, cardiovascular diseases (CVD), and cancer. We also addressed the shortcomings of functional research on soybean proteins and peptides in chronic diseases and the possible directions in the future.

Preclinical and clinical evidence for the treatment of non-alcoholic fatty liver disease with soybean: A systematic review and meta-analysis

Non-alcoholic fatty liver disease (NAFLD), a prevalent public health issue, involves the accumulation of triglycerides in hepatocytes, which is generally considered to be an early lesion of liver fibrosis and cirrhosis. Thus, the development of treatments for NAFLD is urgently needed. This study explored the preclinical and clinical evidence of soybeans to alleviate NAFLD. Studies indexed in three relevant databases-Web of Science, PubMed, and Embase-between January 2002 and August 2022 were retrieved. A total of 13 preclinical studies and five RCTs that included 212 animals and 260 patients were included in the present analysis. The preclinical analysis showed that liver function indices (AST, SMD = -1.41, p < 0.0001 and ALT, SMD = -1.47, p < 0.0001) were significantly improved in the soybean group compared to the model group, and fatty liver indicators (TG, SMD = -0.78, p < 0.0001; TC, SMD = -1.38, p < 0.0001) and that oxidative stress indices (MDA, SMD = -1.09, p < 0.0001; SOD, SMD = 1.74, p = 0.022) were improved in the soybean group. However, the five RCTs were not entirely consistent with the preclinical results; however, the results confirmed the protective effect on the liver. The results of the clinical RCTs showed that soybean significantly affected liver function, fatty liver, and oxidative stress indicators (ALT, SMD = -0.42, p = 0.006; TG, SMD = -0.31, p = 0.039; MDA, SMD = -0.76, p = 0.007). The current meta-analysis combined preclinical and clinical studies and verified that soybean could protect the liver in NAFLD by regulating lipid metabolism and oxidative stress factors via the Akt/AMPK/PPARα signaling pathway. Soybean might be a promising therapeutic agent for treating non-alcoholic fatty liver disease. Systematic Review Registration: (https://www.crd.york.ac.uk/prospero/#myprospero), identifier (CRD42022335822).

Black and Yellow Soybean Consumption Prevents High-Fat Diet-Induced Obesity by Regulating Lipid Metabolism in C57BL/6 Mice

To evaluate the antiobesity effects of yellow and black soybean, C57BL/6 mice were provided with a normal diet, high-fat diet, HFD-containing yellow soybean powder (YS), and black soybean powder (BS) for six weeks. Compared with the HFD group, both YS and BS decreased body weight by 30.1% and 37.2% and fat in tissue by 33.3% and 55.8%, respectively. Simultaneously, both soybeans significantly reduced the serum triglyceride and total cholesterol levels and regulated the lipogenic mRNA expressions of Pparγ, Acc, and Fas genes in the liver, supporting reduced body adiposity. Furthermore, BS significantly increased Pgc-1α and Ucp1 mRNA expression levels in epididymal adipose tissue, indicating thermogenesis is the key mechanism of BS. Taken together, our findings suggest that both soybeans prevent high-fat diet-induced obesity in mice by regulating lipid metabolism, and BS, in particular, has a greater antiobesity potential than YS.

Dietary Combination of Fish Oil and Soy β-Conglycinin Inhibits Fat Accumulation and Reduces Blood Glucose Levels by Altering Gut Microbiome Composition in Diabetic/Obese KK-A y Mice

Dietary fish oil containing n-3 polyunsaturated fatty acids provides health benefits by lowering lipid levels in the liver and serum. β-Conglycinin (βCG) is a major constituent protein in soybean with many physiological effects, such as lowering blood triglyceride levels, preventing obesity and diabetes, and improving hepatic lipid metabolism. However, the combined effects of fish oil and βCG remain unclear. Here, we investigated the effects of a dietary combination of fish oil and βCG on lipid and glucose parameters in diabetic/obese KK-A ^y mice. KK-A ^y mice were divided into three groups: control, fish oil, and fish oil + βCG; these groups were fed a casein-based diet containing 7% (w/w) soybean oil, a casein-based diet containing 2% (w/w) soybean oil and 5% (w/w) fish oil, and a βCG-based diet containing 2% (w/w) soybean oil and 5% (w/w) fish oil, respectively. The effects of the dietary combination of fish oil and βCG on blood biochemical parameters, adipose tissue weight, expression levels of fat- and glucose metabolism-related genes, and cecal microbiome composition were evaluated. The total white adipose tissue weight (p < 0.05), levels of total serum cholesterol (p < 0.01), triglyceride (p < 0.01), and blood glucose (p < 0.05), and expression levels of fatty acid synthesis-related genes (including Fasn (p < 0.05) and Acc (p < 0.05)), and glucose metabolism-related genes (such as Pepck (p < 0.05)) were lower in the fish oil and fish oil + βCG groups than in the control group. Furthermore, the relative abundance of Bacteroidaceae and Coriobacteriaceae differed significantly between the fish oil + βCG and control groups. These findings suggest that dietary intake of fish oil + βCG may prevent obesity and diabetes, alleviate lipid abnormalities, and alter the gut microbiome composition in diabetic/obese KK-A ^y mice. Further research is needed to build on this study to evaluate the health benefits of major components of Japanese food.

Hypolipidemic Effects of Soy Protein and Isoflavones in the Prevention of Non-Alcoholic Fatty Liver Disease- A Review

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and affects about 25% of the population globally. Obesity and diabetes are the main causes of the disease characterized by excessive accumulation of lipids in the liver. There is currently no direct pharmacological treatments for NAFLD. Dietary intervention and lifestyle modification are the key strategies in the prevention and treatment of the disease. Soy consumption is associated with many health benefits such as decreased incidence of coronary heart disease, type-2 diabetes, atherosclerosis and obesity. The hypolipidemic functions of soy components have been shown in both animal studies and human clinical trials. Dietary soy proteins and associated isoflavones suppressed the formation and accumulation of lipid droplets in the liver and improved NAFLD-associated metabolic syndrome. The molecular mechanism(s) underlying the effects of soy components are mainly through modulation of transcription factors, sterol regulatory element-binding protein-1 and peroxisome proliferator-activated receptor-γ2, and expressions of their target genes involved in lipogenesis and lipolysis as well as lipid droplet-promoting protein, fat-specific protein-27. Inclusion of appropriate amounts of soy protein and isoflavones in the diets might be a useful approach to decrease the prevalence of NAFLD and mitigate disease burden.

Functional and Sensorial Properties of Chicken Sausage Supplemented with Banana Peel Flours of Different Varieties

Meat products are widely consumed worldwide and, as a result, they may be an exciting supplier of health benefits due to the need for better formulations, such as reduced fat and increased fibre in processed meats. This study was carried out to determine how the banana peel (BP) flour of Saba (Musa balbisiana) and Berangan (Musa acuminata) affect the functional properties and sensory acceptance of chicken sausage. Berangan BPs showed better water- and oil-holding capacity than Saba BP flour. Conversely, Saba BP flour exhibited better swelling power, but was less soluble than Berangan BP flour. Sausages containing high BPs, especially Saba banana, had a more rigid texture, a high storage modulus, and a darker colour. The ability to retain more water in Berangan peel positively affected the sausage’s textural and rheological properties. With 2%, chicken sausage received the highest sensory score, with Saba BP-containing sausage following closely behind. However, adding >2% BP of both varieties negatively affected the sausage texture and colour, resulting in reduced sensory acceptance. Thus, the BP from Saba and Berangan bananas showed promise as a potential value-adding ingredient in the formulation of functional meat products. In addition, it has potential health benefits, such as increased dietary fibre.

Current innovations in nutraceuticals and functional foods for intervention of non-alcoholic fatty liver disease

As innovations in global agricultural production and food trading systems lead to major dietary shifts, high morbidity rates from non-alcoholic fatty liver disease (NAFLD), accompanied by elevated risk of lipid metabolism-related complications, has emerged as a growing problem worldwide. Treatment and prevention of NAFLD and chronic liver disease depends on the availability of safe, effective, and diverse therapeutic agents, the development of which is urgently needed. Supported by a growing body of evidence, considerable attention is now focused on interventional approaches that combines nutraceuticals and functional foods. In this review, we summarize the pathological progression of NAFLD and discuss the beneficial effects of nutraceuticals and the active ingredients in functional foods. We also describe the underlying mechanisms of these compounds in the intervention of NAFLD, including their effects on regulation of lipid homeostasis, activation of signaling pathways, and their role in gut microbial community dynamics and the gut-liver axis. In order to identify novel targets for treatment of lipid metabolism-related diseases, this work broadly explores the molecular mechanism linking nutraceuticals and functional foods, host physiology, and gut microbiota. Additionally, the limitations in existing knowledge and promising research areas for development of active interventions and treatments against NAFLD are discussed.

Molecular forces governing protein-protein interaction: Structure-function relationship of complexes protein in the food industry

The application of protein-protein interaction (PPI) has been widely used in various industries, such as food, nutraceutical, and pharmaceutical. A deeper understanding of PPI is needed, and the molecular forces governing proteins and their interaction must be explained. The design of new structures with improved functional properties, e.g., solubility, emulsion, and gelation, has been fueled by the development of structural and colloidal building blocks. In this review, the molecular forces of protein structures are discussed, followed by the relationship between molecular force and structure, ways of a bind of proteins together in solution or at the interface, and functional properties. A more detailed look is thus taken at the relationship between the various influencing factors on molecular forces involved in PPI. These factors include protein properties, such as types, concentration, and mixing ratio, and solvent conditions, such as ionic strength and pH. This review also summarizes methods tha1t are capable of identifying molecular forces in protein and PPI, as well as characterizing protein structure.

The roles of banana peel powders to alter technological functionality, sensory and nutritional quality of chicken sausage

Chicken sausages included with three different quantities of banana (Musa balbisiana) peel powder. The technological properties (cooking yield, texture, water-holding capacity, color, rheology, and texture), composition, and sensory acceptability were assessed. In storage study, lipid oxidation of the best formulation from the sensory score was evaluated. The inclusion of banana peel powder (BPP) raises the nutritional value with regard to an increase in dietary fiber and a reduction in the sausage fat content. The addition of BPP also causes a significant increase in the cooking yield and water-holding capacity. Additionally, storage modulus values increase with the increase in the BPP's concentration. However, with BPP incorporation, a hard texture and darkening of the sausage were observed. Interestingly, our findings exhibit the compromise in microstructural of chicken sausage with high percentage of BPP manifested by the high storage modulus and hardness but with low resistance toward stress, short linear viscoelastic region. This aspect also caused a significant change in the sensory score. The TBA value in the sausage containing 2% BPP exhibited a delay in lipid oxidation up to 55%, prompting its antioxidant potential. Generally, the incorporation of BPP to chicken sausage changes its properties. BPP has been a potential candidate as a value-adding ingredient that may be used during meat preparation since it positively influences the nutritional value and specific technological properties of the food.

Evaluation of Antiobesity Activity of Soybean Meal Products Fermented by Lactobacillus plantarum FPS 2520 and Bacillus subtilis N1 in Rats Fed with High-Fat Diet

Single strain or mixed strains of Lactobacillus plantarum FPS 2520 and Bacillus subtilis N1 were used to ferment soybean meal (SBM), and the antiobesity activity of the fermented SBM product was investigated in rats fed with high-fat diet (HFD). After fermentation, free amino nitrogen, total peptide, and isoflavone contents were markedly raised, and genistein and daidzein were the major isoflavones in the fermented SBM. After fed with HFD for 10 weeks, obese Sprague-Dawley rats were orally treated with various fermented products for 6 weeks. The body weight gains, as well as weights of abdominal fat and epididymis fat, of rats fed with fermented SBM products were significantly downregulated. The treatment with the mixed-strains fermented SBM product significantly decreased plasma levels of triglyceride (TG), total cholesterol (TC), and low-density lipoprotein-cholesterol, but increased the level of high-density lipoprotein-cholesterol. Moreover, the levels of TG, TC, fatty acid synthase, and acetyl-CoA carboxylase (ACC) in liver were diminished, and the activities of hormone-sensitive lipase and lipoprotein lipase in adipose tissue were augmented. Taken together, these data demonstrated the antiobesity activity of fermented SBM products, among which the product fermented by the mixed strains being the most effective one. Therefore, these fermented SBM products are potential to be developed as functional foods or additives for treatment of obesity and prevention against obesity-induced complications.

O/W Pickering emulsions stabilized by Flammulina velutipes polysaccharide nanoparticles as a fat substitute: the effects of phase separation on emulsified sausage's techno-functional and sensory quality

BACKGROUND

The application of Pickering emulsion stabilized by food-derived particles is of great interest in the food field, including meat processing. However, the creaming phenomenon is a thorny problem and may impact the resulting product quality. Here, we used polysaccharide nanoparticles from Flammulina velutipes (FVPN) as a stabilizer to prepare a oil/water Pickering emulsion and partly replace the original fat of common emulsified sausage, focusing on exploring the influence of phase separation on the sausage's techno-functional and sensory quality, with the aim of developing a new alternative fat substitute.

RESULTS

Reformulated sausages showed increases in moisture (53.24-64.85%) and protein content (11.97-12.76%), but were reduced in fat content (27.28-18.76%). The increased FPOE (FVPN-palm oil emulsion; substitution rate 5-37%) amount in sausages resulted in significantly reduced (P < 0.05) cooking loss (18.87-8.63%). Meanwhile, emulsion improved the springiness and cohesiveness of sausage and significantly reduced (P < 0.05) hardness and chewiness when the replacement amount was less than 20%. Experimental sausages attained a more compact pore structure without harming sensory characteristics. Compared with creaming emulsion, pristine emulsion resulted in a sausage with higher moisture content, lower cooking loss, better elasticity and denser structure.

CONCLUSION

The characteristics of sausages could be influenced by emulsion stability. Emulsion, especially with no creaming, can be effectively used as fat substitute at a level of 20% or less without adversely affecting the sensory characteristics of emulsified sausages. The incorporation of FPOE provides the potential for developing a new alternative approach for animal fat improvement in meat products. © 2019 Society of Chemical Industry.

Trypsin inhibitors: promising candidate satietogenic proteins as complementary treatment for obesity and metabolic disorders?

The increase in non-communicable chronic diseases has aroused interest in the research of adjuvants to the classic forms of treatments. Obesity and metabolic syndrome are the main targets of confrontation because they relate directly to other chronic diseases. In this context, trypsin inhibitors, molecules with wide heterologous application, appear as possibilities in the treatment of overweight and obesity due to the action on satiety related mechanisms, mainly in the modulation of satiety hormones, such as cholecystokinin. In addition, trypsin inhibitors have the ability to also act on some biochemical parameters related to these diseases, thus, emerging as potential candidates and promising molecules in the treatment of the obesity and metabolic syndrome. Thus, the present article proposes to approach, through a systematic literature review, the advantages, disadvantages and viabilities for the use of trypsin inhibitors directed to the treatment of overweight and obesity.

Modulation of Gut Microbiota by Soybean 7S Globulin Peptide That Involved Lipopolysaccharide-Peptide Interaction

Soybean protein exhibits nutritional significance for the control of metabolic syndrome, and evidence suggests that gut microbiota are implicated in the control of metabolic disorders. This study aimed to investigate the modulation of pepsin-released peptides of soybean 7S globulin on gut microbiota and possible association between changes of gut microbiota composition and lipopolysaccharide (LPS)-peptide interaction. In vitro fermentation experiments showed that the extension region (ER) fragments of soybean 7S globulin selectively suppressed proinflammatory Gram-negative bacteria. ER peptides also promoted the highest production of short-chain fatty acids (SCFAs), which were associated with increase of the relative abundance of Lachnospiraceae and Lactobacillaceae. Isothermal titration calorimetry (ITC) and Langmuir monolayer studies demonstrated that ER peptides exhibited high affinity to LPS in the presence of Ca²⁺ and developed into β-sheet-rich aggregate structures, thus weakening the stability of LPS monolayers. This finding supplies a possible explanation for improvement of the effects of soybean 7S globulin on metabolic disease.

Dietary soybean protein ameliorates high-fat diet-induced obesity by modifying the gut microbiota-dependent biotransformation of bile acids

The consumption of soybean protein has well-known favorable metabolic effects (e.g., reduced body weight, body fat, hyperglycemia, insulin resistance, hepatic steatosis, and lipogenesis). These effects of soy protein have been linked to modulation by the gut microbiota; however, the dynamic interplay among these factors remains unclear. Accordingly, we examined the metabolic phenotype, intestinal BA pool, and the gut microbiome of male C57BL/6 mice that were randomized to receive either a regular high-fat diet (HFD) or HFD that contained soybean protein isolate (SPI) in place of dairy protein. The intake of SPI significantly reduced the HFD-induced weight gain and adipose tissue mass accumulation and attenuated hepatic steatosis. Along with an enhancement in the secretion of intestinal Glucagon-like peptide-1 (GLP-1), an enlarged cecal BA pool with an elevated secondary/primary BA ratio was observed in the mice that consumed SPI, while fecal BA excretion remained unaltered. SPI also elicited dramatic changes in the gut microbiome, characterized by an expansion of taxa that may be involved in the biotransformation of BAs. The observed effects were abolished in germ-free (GF) mice, indicating that they were dependent on the microbiota. These findings collectively indicate that the metabolic benefits of SPI under the HFD regime may arise from a microbiota-driven increase in BA transformation and increase in GLP-1 secretion.

Dietary mung bean protein reduces high-fat diet-induced weight gain by modulating host bile acid metabolism in a gut microbiota-dependent manner

The 8-globulin-rich mung bean protein (MPI) suppresses hepatic lipogenesis in rodent models and reduces fasting plasma glucose and insulin levels in obese adults. However, its effects on mitigating high fat diet (HFD)-induced obesity and the mechanism underlying these effects remain to be elucidated. Herein, we examined the metabolic phenotype, intestinal bile acid (BA) pool, and gut microbiota of conventionally raised (CONV-R) male C57BL/6 mice and germ-free (GF) mice that were randomized to receive either regular HFD or HFD containing mung bean protein isolate (MPI) instead of the dairy protein present in regular HFD. MPI intake significantly reduced HFD-induced weight gain and adipose tissue accumulation, and attenuated hepatic steatosis. Enhancement in the secretion of intestinal glucagon-like peptide-1 (GLP-1) and an enlarged cecal and fecal BA pool of dramatically elevated secondary/primary BA ratio were observed in mice that had consumed MPI. These effects were abolished in GF mice, indicating that the effects were dependent upon the presence of the microbiota. As revealed by 16S rRNA gene sequence analysis, MPI intake also elicited dramatic changes in the gut microbiome, such as an expansion of taxa belonging to the phylum Bacteroidetes along with a reduced abundance of the Firmicutes.

Improvement of glucose and lipid metabolism via mung bean protein consumption: clinical trials of GLUCODIA™ isolated mung bean protein in the USA and Canada

The aim of the present study was to confirm the effects of a commercially available mung bean protein isolate (GLUCODIA™) on glucose and lipid metabolism. The main component of GLUCODIA™ is 8S globulin, which constitutes 80 % of the total protein. The overall structure of this protein closely resembles soyabean β-conglycinin, which accounts for 20 % of total soya protein (soya protein isolate; SPI). Many physiological beneficial effects of β-conglycinin have been reported. GLUCODIA™ is expected to produce beneficial effects with fewer intakes than SPI. We conducted two independent double-blind, placebo-controlled clinical studies. In the first (preliminary dose decision trial) study, mung bean protein was shown to exert physiological beneficial effects when 3·0 g were ingested per d. In the second (main clinical trial) study, mung bean protein isolate did not lower plasma glucose levels, although the mean insulin level decreased with consumption of mung bean protein. The homeostatic model assessment of insulin resistance (HOMA-IR) values significantly decreased with mung bean protein. The mean TAG level significantly decreased with consumption of mung bean protein isolate. A significant increase in serum adiponectin levels and improvement in liver function enzymes were observed. These findings suggest that GLUCODIA™ could be useful in the prevention of insulin resistance and visceral fat accumulation, which are known to trigger the metabolic syndrome, and in the prevention of liver function decline.

Effects of 12-week supplementation of marine Omega-3 PUFA-based formulation Omega3Q10 in older adults with prehypertension and/or elevated blood cholesterol

Backgrounds

To study the effects of supplementation of a marine omega-3 poly-unsaturated fatty acids (n3-PUFA) formulation (Omega3Q10) in older adults with hypertension and/or hypercholesterolemia.

Methods

A total of 97 people were enrolled to receive 12-week supplementation of either Omega3Q10 (n = 48) or soybean oil (n = 49). Total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), and hypertension-related symptoms were determined before and after the supplementation.

Results

There were no baseline differences between the two groups. Omega3Q10 supplementation significantly reduced diastolic blood pressure (DBP) (from 81.6 ± 5.3 mmHg to 79.3 ± 5.2 mmHg, P < 0.05). Blood concentrations of TC and LDL-C decreased significantly and blood HDL-C level increased significantly after 12 weeks of Omega3Q10 (5.5 ± 0.7 vs. 5.3 ± 0.5, P < 0.05; 3.7 ± 0.8 vs. 3.3 ± 0.6, P < 0.05; 1.2 ± 0.6 vs. 1.3 ± 0.5, P < 0.05, respectively) and soybean oil supplementation (5.7 ± 0.8 vs. 5.6 ± 0.7, P < 0.05; 3.6 ± 0.7 vs. 3.4 ± 0.8, P < 0.05; 1.0 ± 0.8 vs. 1.2 ± 0.7, P < 0.05, respectively) but no group differences were found. A significantly greater proportion of the people in the Omega3Q10 group became free from headache and palpitations & chest tightness symptoms after the 12-week supplementation compared to that of the soybean oil group (95.5% vs. 71.4%, P < 0.01; 95.8 vs. 75.5%, P < 0.01, respectively).

Conclusion

12-week supplementation of Fish oil-based PUFA appear to be more effective in improving DBP and hypertension-related symptoms than soybean oil in old adults with hypertension and hypercholesterolemia although both supplementation improved TC, LDL-C and HDL-C concentrations.

Effect of Seyoeum on Obesity, Insulin Resistance, and Nonalcoholic Fatty Liver Disease of High-Fat Diet-Fed C57BL/6 Mice

BACKGROUND

This study was performed to evaluate the effect of Seyoeum (SYE), a novel herbal meal replacement, on insulin resistance and nonalcoholic fatty liver disease (NAFLD) in obese mice fed with a high-fat diet (HFD).

METHODS

SYE contained six kinds of herbal powder such as Coix lacryma-jobi, Oryza sativa, Sesamum indicum, Glycine max, Liriope platyphylla, and Dioscorea batatas. Male C57BL/6 mice were divided into four groups: normal chow (NC), HFD, SYE, and HFD plus SYE (HFD + SYE). The mice in groups other than NC were fed HFD for 9 weeks to induce obesity and then were fed each diet for 6 weeks. Clinical markers related to obesity, diabetes, and NAFLD were examined and gene expressions related to inflammation and insulin receptor were determined.

RESULTS

Compared with HFD group, body weight, serum glucose, serum insulin, HOMA-IR, total cholesterol, triglyceride, epididymal fat pad weight, liver weight, and inflammatory gene expression were significantly reduced in SYE group. Insulin receptor gene expression increased in SYE group.

CONCLUSIONS

Based on these results, we conclude that SYE improved obesity and insulin resistance in high-fat fed obese mice. Our findings suggest that SYE could be a beneficial meal replacement through these antiobesity and anti-insulin resistance effects.

The α' subunit of β-conglycinin and various glycinin subunits of soy are not required to modulate hepatic lipid metabolism in rats

PURPOSE

This study examined the effect of soy proteins with depletion of different subunits of the two major storage proteins, β-conglycinin and glycinin, on hepatic lipids and proteins involved in lipid metabolism in rats, since the bioactive component of soy responsible for lipid-lowering is unclear.

METHODS

Weanling Sprague Dawley rats were fed diets containing either 20% casein protein in the absence (casein) or presence (casein + ISF) of isoflavones or 20% alcohol-washed soy protein isolate (SPI) or 20% soy protein concentrates derived from a conventional (Haro) or 2 soybean lines lacking the α' subunit of β-conglycinin and the A1-3 (1TF) or A1-5 (1a) subunits of glycinin. After 8 weeks, the rats were necropsied and liver proteins and lipids were extracted and analysed.

RESULTS

The results showed that soy protein diets reduced lipid droplet accumulation and content in the liver compared to casein diets. The soy protein diets also decreased the level of hepatic mature SREBP-1 and FAS in males, with significant decreases in diets 1TF and 1a compared to the casein diets. The effect of the soy protein diets on female hepatic mature SREBP-1, FAS, and HMGCR was confounded since casein + ISF decreased these levels compared to casein alone perhaps muting the decrease by soy protein. A reduction in both phosphorylated and total STAT3 in female livers by ISF may account for the gender difference in mechanism in the regulation and protein expression of the lipid modulators.

CONCLUSIONS

Overall, soy protein deficient in the α' subunit of β-conglycinin and A1-5 subunits of glycinin maintain similar hypolipidemic function compared to the conventional soy protein. The exact bioactive component(s) warrant identification.

Soy Protein Isolate Suppresses Lipodystrophy-induced Hepatic Lipid Accumulation in Model Mice

Lipodystrophies are acquired and genetic disorders characterized by the complete or partial absence of body fat with a line of metabolic disorders, including hepatic steatosis. Because soy protein isolate (SPI) has been reported to reduce cholesterol and triglyceride levels in animals and humans, we explored the effect of SPI on the pathophysiology of hepatic lipid accumutaion in a diet-induced lipodystrophy model mice. Four weeks of the lipodystrophy model diet induced hepatic lipid accumulation concomitant with marked deficiencies of adipose tissue and serum adipocytokines in mice. However, supplementing the lipodystrophy model diet with SPI could alleviate the hepatic lipid acculation without affecting the lipoatrophic effect of the diet. Enhanced lipogenesis is the principal mechanism of hepatic steatosis in this model, but SPI supplementation significantly attenuated the increase in enzyme activity and/or mRNA expression. Additionally, SPI supplementation upregulated the hepatic mRNA expression of an enzyme involved in cholesterol catabolism. In conclusion, our results indicate the possibility of dietary SPI to attenuate lipodystorophy-induced hepatic steatosis through the direct reduction of hepatic lipogenesis without affecting adipocytokine production.

Dietary Mung Bean Protein Reduces Hepatic Steatosis, Fibrosis, and Inflammation in Male Mice with Diet-Induced, Nonalcoholic Fatty Liver Disease

BACKGROUND

As the prevalence of nonalcoholic fatty liver disease (NAFLD), including steatosis and nonalcoholic steatohepatitis, is increasing, novel dietary approaches are required for the prevention and treatment of NAFLD.

OBJECTIVE

We evaluated the potential of mung bean protein isolate (MuPI) to prevent NAFLD progression.

METHODS

In Expts. 1 and 2, the hepatic triglyceride (TG) concentration was compared between 8-wk-old male mice fed a high-fat diet (61% of energy from fat) containing casein, MuPI, and soy protein isolate and an MuPI-constituent amino acid mixture as a source of amino acids (18% of energy) for 4 wk. In Expt. 3, hepatic fatty acid synthase (Fasn) expression was evaluated in 8-wk-old male Fasn-promoter-reporter mice fed a casein- or MuPI-containing high-fat diet for 20 wk. In Expt. 4, hepatic fibrosis was examined in 8-wk-old male mice fed an atherogenic diet (61% of energy from fat, containing 1.3 g cholesterol/100 g diet) containing casein or MuPI (18% of energy) as a protein source for 20 wk.

RESULTS

In the high fat-diet mice, the hepatic TG concentration in the MuPI group decreased by 66% and 47% in Expt. 1 compared with the casein group (P < 0.001) and the soy protein isolate group (P = 0.001), respectively, and decreased by 56% in Expt. 2 compared with the casein group (P = 0.011). However, there was no difference between the MuPI-constituent amino acid mixture and casein groups in Expt. 2. In Expt. 3, Fasn-promoter-reporter activity and hepatic TG concentration were lower in the MuPI group than in those fed casein (P < 0.05). In Expt. 4, in mice fed an atherogenic diet, hepatic fibrosis was not induced in the MuPI group, whereas it developed overtly in the casein group.

CONCLUSION

MuPI potently reduced hepatic lipid accumulation in mice and may be a potential foodstuff to prevent NAFLD onset and progression.

Single ingestion of soy β-conglycinin induces increased postprandial circulating FGF21 levels exerting beneficial health effects

Soy protein β-conglycinin has serum lipid-lowering and anti-obesity effects. We showed that single ingestion of β-conglycinin after fasting alters gene expression in mouse liver. A sharp increase in fibroblast growth factor 21 (FGF21) gene expression, which is depressed by normal feeding, resulted in increased postprandial circulating FGF21 levels along with a significant decrease in adipose tissue weights. Most increases in gene expressions, including FGF21, were targets for the activating transcription factor 4 (ATF4), but not for peroxisome proliferator-activated receptor α. Overexpression of a dominant-negative form of ATF4 significantly reduced β-conglycinin-induced increases in hepatic FGF21 gene expression. In FGF21-deficient mice, β-conglycinin effects were partially abolished. Methionine supplementation to the diet or primary hepatocyte culture medium demonstrated its importance for activating liver or hepatocyte ATF4-FGF21 signaling. Thus, dietary β-conglycinin intake can impact hepatic and systemic metabolism by increasing the postprandial circulating FGF21 levels.

Comparison of endpoints relevant to toxicity assessments in 3 generations of CD-1 mice fed irradiated natural and purified ingredient diets with varying soy protein and isoflavone contents

Diet is an important variable in toxicology. There are mixed reports on the impact of soy components on energy utilization, fat deposition, and reproductive parameters. Three generations of CD-1 mice were fed irradiated natural ingredient diets with varying levels of soy (NIH-41, 5K96, or 5008/5001), purified irradiated AIN-93 diet, or the AIN-93 formulation modified with ethanol-washed soy protein concentrate (SPC) or SPC with isoflavones (SPC-IF). NIH-41 was the control for pairwise comparisons. Minimal differences were observed among natural ingredient diet groups. F0 males fed AIN-93, SPC, and SPC-IF diets had elevated glucose levels and lower insulin levels compared with the NIH-41 group. In both sexes of the F1 and F2 generations, the SPC and SPC-IF groups had lower body weight gains than the NIH-41 controls and the AIN-93 group had an increased percent body fat at postnatal day 21. AIN-93 F1 pups had higher baseline glucose than NIH-41 controls, but diet did not significantly affect breeding performance or responses to glucose or uterotrophic challenges. Reduced testes weight and sperm in the AIN-93 group may be related to low thiamine levels. Our observations underline the importance of careful selection, manufacturing procedures, and nutritional characterization of diets used in toxicological studies.

The Role of Food Peptides in Lipid Metabolism during Dyslipidemia and Associated Health Conditions

Animal and human clinical studies have demonstrated the ability of dietary food proteins to modulate endogenous lipid levels during abnormal lipid metabolism (dyslipidemia). Considering the susceptibility of proteins to gastric proteolytic activities, the hypolipidemic functions of proteins are possibly due, in part, to their peptide fragments. Food-derived peptides may directly modulate abnormal lipid metabolism in cell cultures and animal models of dyslipidemia. The peptides are thought to act by perturbing intestinal absorption of dietary cholesterol and enterohepatic bile acid circulation, and by inhibiting lipogenic enzymatic activities and gene expression in hepatocytes and adipocytes. Recent evidence indicates that the hypolipidemic activities of some peptides are due to activation of hepatic lipogenic transcription factors. However, detailed molecular mechanisms and structural requirements of peptides for these activities are yet to be elucidated. As hypolipidemic peptides can be released during enzymatic food processing, future studies can explore the prospects of combating metabolic syndrome and associated complications using peptide-rich functional food and nutraceutical products.