Soy Protein and Chronic Kidney Disease: An Updated Review

Characteristics of soybean (Glycine max) protein hydrolysate by bromelain and its effect on inflammation and kidney disorders in gentamicin-induced male Wistar rats

Objectives

Soybeans have various positive effects on health, including anti-inflammatory and preventing kidney damage. There is concern regarding the phytoestrogen content due to the high isoflavone content in soybeans. Various forms of soybean processing have been tried; in this study, the hydrolysis method will be used to obtain the active substance Arginine-Glycine-Aspartate (RGD) tripeptide in soybean protein hydrolyzed by bromelain (SPHB). The research aimed to determine the characteristics and influence of SPHB on kidney function, inflammation, body weight, and estrogen in male Wistar rats induced by gentamicin.

Materials and Methods

Soybeans (Glycine max) are hydrolyzed using the proteolytic enzyme Bromelain from pineapples. The proteomics was investigated using Liquid-Chromatography Mass Spectroscopy Tandem (LC-MS/MS). SPHB in three doses would be tested for 28 days on male Wistar rats induced by gentamicin. The parameters measured were body weight, high-sensitive cell reactive protein (hs-CRP) levels, urea, creatinine, and estrogen levels.

Results

SPHB has a low molecular weight (LMW) of 10 kDa and contains RGD in the lunasin sequence. SPHB showed no effect on body weight (P>0.05). The impact of SPHB on hs-CRP, urea, and creatinine showed differences significantly from the positive control, especially SPHB at a dose of 112 mg/day (P<0.01). Meanwhile, SPHB has almost no effect on estrogen levels.

Conclusion

The administration of SPHB with LMW and contains lunasin showed decreased inflammation and kidney function parameters but did not affect body weight and estrogen levels in induced gentamicin Wistar rats.

High-Protein Processed Foods: Impact on Diet, Nutritional Status, and Possible Effects on Health

Proteins are macronutrients with multiple health benefits, but excessive consumption can negatively affect health. This study aimed to evaluate the characteristics of a sample of high-protein processed foods (HPPFs), describe how their consumption affects dietary balance, and acquire knowledge of the consumption patterns of these products in a Spanish population. A sample of HPPFs available in supermarkets and on websites was collected. The contribution to recommended protein intakes was calculated using national and international references and considering the single consumption of the HPPFs and the product plus 150 g of meat. Furthermore, an online survey was conducted among a convenience sample. A total of 36 enriched protein products were evaluated. The percentage of proteins in these products ranges from 10 to 88%. The contribution of the protein recommended intake was within a range of 87.4-306.6% and 66.4-232.8% (women and men, respectively), only considering the additional proteins from 150 g of meat. One hundred thirty-nine participants completed the survey; 67.6% affirmed that they had consumed HPPFs, and half consumed them without following any consumption control. Since these products are accessible to everyone in supermarkets and protein intake is generally higher than the recommended limits, regulating the mass sale of HPPFs is essential to ensure they do not lead to protein overconsumption.

Relationships of beans intake with chronic kidney disease in rural adults: A large-scale cross-sectional study

Background and aims

Dietary factors play an important role in the development of chronic kidney disease (CKD). However, evidence on the relationship of beans consumption with CKD remains limited and inconclusive, especially in the middle-and low-income populations. The current study aimed to investigate the relationships of beans intake with indicators of kidney injury and CKD prevalence in rural adults.

Methods

A total of 20,733 rural adults from the Henan Rural Cohort Study in 2018–2022 were included. The total beans intake was collected using a validated food frequency questionnaire. Indicators of kidney injury and CKD was determined by the estimated glomerular filtration rate and the urinary albumin to creatinine ratio. Generalized linear regression and logistic regression models were applied to estimate the relationship of beans intake with continuous and dichotomized indicators of renal function, respectively.

Results

Of the 20,733 participants, 2,676 (12.91%) subjects were identified as CKD patients. After adjusting for potential confounders, participants in the higher quartiles of beans intake had a lower prevalence of CKD (odds ratio and 95% confidence interval, OR (95%CI); Q2: 0.968(0.866–1.082); Q3: 0.836(0.744–0.939); Q4: 0.854(0.751–0.970)) and albuminuria (Q2: 0.982(0.875–1.102); Q3: 0.846(0.750–0.954); Q4: 0.852 (0.746–0.973)), compared with the Q1. Per 50 g/day increment in beans intake was significantly associated with a 5 and 4% decreased prevalence of albuminuria and CKD, respectively. These inverse relationships were also significant in the subgroups of men, elder, and high-income participants (p &lt; 0.05).

Conclusion

Dietary beans intake was inversely associated with the prevalence of albuminuria and CKD in rural adults, suggesting that promoting soy food intake might help reduce the occurrence of CKD in rural adults.

[Soy protein as part of a low-protein diet is a new direction in cardio- and nephroprotection in patients with 3B-4 stages of chronic kidney disease: prospective, randomized, controlled clinical study]

BACKGROUND

It has been established that the use of a low-protein diet (LPD) in combination with ketoanalogues (KA) of essential amino acids can contribute to cardio- and nephroprotection in chronic kidney disease (CKD). Moreover, it has been shown that replacing part of the animal protein with soy protein (SP) in the diet contributed to more pronounced nephro- and cardioprotection in CKD, however, the data, available in the literature, are mainly represented by experimental studies.

AIM

To compare the effects of 2 types of diets on the main parameters of nephro- and cardioprotection in patients with CKD.

MATERIALS AND METHODS

We have conducted a prospective, randomized, controlled clinical study which included 85 patients with 3B4 stages of CKD, compliant to LPD (0.6 g of protein/kg body weight) + KA (1 tablet/5 kg body weight). 43 patients (Group 1) received LPD with replacing animal protein with soy (60% soy protein + 40% another vegetable proteins) + KA, and 42 patients (control group, Group 2) received LPD (60% animal protein + 40% vegetable protein) + KA, within 12 months.

RESULTS

The dietary substitution of animal protein with SP to a greater extent delayed the decrease in glomerular filtration rate (-5.9% vs -13.3%; p=0.048), the increase in left ventricular hypertrophy (+4.7% vs +12.3%; p=0.042), as well as the increase in central systolic blood pressure (+2.6% vs +13.0%; p=0.021), augmentation index (+7.6% vs +23.3%; p=0.010), slowed down the decrease in lean body mass in men (+0.9% vs -11.2%; p=0.017) and women (-1.8% vs -10.3%; p=0.024), increase in phosphorus (-10.3% vs +13.0%; p=0.029), cholesterol (-10.7% vs -3.4%; p=0.047) and urea (+6.3% vs +19.6%; p=0.035) serum levels.

CONCLUSION

The use of LPD with substitution of animal protein with soy protein + KA provides a more pronounced effect on nephro- and cardioprotection as well as maintenance of nutritional status, than conventional LPD + KA in patients with 3B4 stages of CKD.

Soy Phospholipids Exert a Renoprotective Effect by Inhibiting the Nuclear Factor Kappa B Pathway in Macrophages

Complications associated with chronic kidney disease (CKD), which involves kidney inflammation, are a major health problem. Soy protein isolate (SPI) reportedly inhibits CKD exacerbation; however, its detailed action mechanism remains obscure. Therefore, the role of the polar lipid component of SPI in suppressing inflammation was investigated. Zucker fatty rats were divided into three groups and fed a diet containing casein, SPI, or casein + SPI ethanol extract (SPIEE) for 16 weeks. The isoflavones and phospholipids of SPIEE were evaluated for their anti-inflammatory effects. Rats in the SPI and casein + SPIEE groups showed reduced levels of the urinary N-acetyl-β-d-glucosaminidase and renal IL-1β mRNA (an inflammatory marker) compared with those in the casein group. In proximal tubular cells, genistein significantly inhibited monocyte chemoattractant protein-1 (MCP-1) expression induced by an IL-1β stimulus. In macrophages, soybean phospholipids suppressed lipopolysaccharide-induced IL-1β gene expression by inhibiting the phosphorylation of inhibitor κB and p65. Phosphatidylinositol (PI) was found to be essential for inhibition of IL-1β expression. SPIEE inhibited the exacerbation of kidney disease. Genistein and soybean phospholipids, especially soybean-specific phospholipids containing PI, effectively inhibited the inflammatory spiral in vitro. Hence, daily soybean intake may be effective for inhibiting chronic inflammation and slowing kidney disease progression.

Effects of ultrafine grinding time on the functional and flavor properties of soybean protein isolate

Soybean protein isolate (SPI) powders were prepared at different ultrafine grinding time, and the functional and flavor properties of microparticulation SPI were evaluated. With extending ultrafine grinding time, a narrow and uniform particle size distribution in SPI powders was produced. The particle sizes of protein powders at grinding time 0, 2, 4, 6 and 8 h significantly reduced from 217 ± 16.5-137.5 ± 10.7 nm, while the absolute values of zeta-potential significantly increased from 25 ± 0.93-32.4 ± 117 mV (P < 0.05). The microstructure of SPI at grinding time 0-8 h changed from smooth to irregular. With prolonging the ultrafine grinding processing time, the solubility, foaming and emulsifying properties of SPI powders were improved, the content ofα-helix, β-sheet and random coils increased, while β-turn decreased. Furthermore, the ultrafine grinding time clearly influenced the volatile compounds of SPI powders. The main flavor compounds were aldehydes, alcohols, acids, ketones and alkanes. SPI powders for grinding time 2, 4, 6 and 8 h exhibited the higher total content of volatile compounds compared to that for 0 h. So the ultrafine grinding treatment at appropriate time could affect the functional and flavor properties of SPI.

Stromal Cell-derived Factor-1 and CXC Chemokine Receptor Type-4 are Associated with Cardiovascular Disease in Patients under Hemodialysis

Background

Cardiovascular disease (CVD) is the most common cause of death among patients with end-stage renal disease especially whom under hemodialysis (HD). Stromal cell-derived factor-1 (SDF-1) and its receptor CXC chemokine receptor type-4 (CXCR4) could contribute to CVD. The main aim of this study was to evaluate the association between SDF-1 and CXCR4 with CVD and its related risk factors in patients under HD.

Methods

Sixty patients under HD and 29 healthy subjects were recruited in the study. The serum levels and relative messenger RNA (mRNA) expressions of SDF-1 and CXCR4 were measured using enzyme-linked immunosorbent assay and real-time polymerase chain reaction in patients and controls, respectively. CVD history of the patients was obtained.

Results

Twenty patients (33.3%) had a history of CVD. The mean levels of serum and relative mRNA expressions of SDF-1 and CXCR4 were higher in patients than controls and also in patients with a history of CVD than patients without it. The serum levels and relative expressions of SDF-1 and CXCR4 were positively correlated with blood urea nitrogen, parathyroid hormone, and high-sensitivity C-reactive protein and inversely correlated with hemoglobin. The history of CVD was the independent predictor of serum levels of SDF-1 and CXCR4 and also relative mRNA expression of CXCR4.

Conclusions

The higher levels of serum and relative mRNA expressions of SDF-1 and CXCR4 were associated with CVD in patients under HD. Furthermore, SDF-1 and CXCR4 were associated with several traditional and uremia-related CVD risk factors in such patients.

Impact of Gut Dysbiosis on Neurohormonal Pathways in Chronic Kidney Disease

Chronic kidney disease (CKD) is a worldwide major health problem. Traditional risk factors for CKD are hypertension, obesity, and diabetes mellitus. Recent studies have identified gut dysbiosis as a novel risk factor for the progression CKD and its complications. Dysbiosis can worsen systemic inflammation, which plays an important role in the progression of CKD and its complications such as cardiovascular diseases. In this review, we discuss the beneficial effects of the normal gut microbiota, and then elaborate on how alterations in the biochemical environment of the gastrointestinal tract in CKD can affect gut microbiota. External factors such as dietary restrictions, medications, and dialysis further promote dysbiosis. We discuss the impact of an altered gut microbiota on neuroendocrine pathways such as the hypothalamus⁻pituitary⁻adrenal axis, the production of neurotransmitters and neuroactive compounds, tryptophan metabolism, and the cholinergic anti-inflammatory pathway. Finally, therapeutic strategies including diet modification, intestinal alpha-glucosidase inhibitors, prebiotics, probiotics and synbiotics are reviewed.