Obesity and Kidney Disease: Hidden Consequences of the Epidemic

The effect of a ketogenic diet on weight loss in CKD: a randomized controlled trial in obese stage G1-3a CKD patients

This study describes a multicentre randomized controlled trial comparing the effects of a ketogenic diet with a low-energy standard diet containing 0.8 g/kg/day on weight loss and metabolic alterations in adult patients with mild-to-moderate non-diabetic chronic kidney disease (CKD) and mild-to-severe obesity. The study is being conducted to understand the impact of the ketogenic diet on weight loss in these patients, as the existing evidence on the ketogenic diet's effect in CKD patients is limited and inconclusive. The study will enrol mild-to moderate adult CKD patients (Stages G1-3a) with albumin to creatinine ratio ≥200 mg/g, without diabetes, with obesity (body mass index ≥30 kg/m2), and stable body weight and estimated glomerular filtration rate from at least 3 months. The primary outcome will be weight loss at 6 months, and secondary outcomes will include adherence to prescribed dietary regimens, body composition changes, changes in standardized blood pressure measurements, metabolic parameters, lipid profile, liver profile, mineral bone disease biomarkers, and changes in renal function and albuminuria. The findings of this study will contribute to a better understanding of the potential benefits and risks of the ketogenic diet in CKD patients with obesity. The results will help guide future research on the ketogenic diet and renal health.

Effects of a protein-restricted diet on body weight and serum tyrosine concentrations in patients with alkaptonuria

In an open-label, controlled study of nitisinone in alkaptonuria (SONIA 2), patients were advised to lower dietary protein intake to reduce serum tyrosine (s-Tyr) levels and the risk of keratopathy. A body weight increase was observed in the nitisinone-treated patients but not in the control group. To investigate the effectiveness and consequence of protein restriction in patients with alkaptonuria, a post-hoc analysis of SONIA 2 was performed. One hundred and thirty-eight patients were randomised (nitisinone: n = 69, controls: n = 69). Comparison of baseline and Month 12 data on 24-h urinary excretion of HGA (u-HGA24) and urea (u-urea24, used as an approximate protein intake measure), tyrosine and body weight were performed using paired t tests. Comparisons of data between groups were made using 2-sample t tests. We found that u-urea24 decreased more in nitisinone-treated than controls. The study centre with lowest average s-Tyr and u-urea24 (nitisinone arm) at Month 12 also had lowest keratopathy incidence (3.1%), while the centre with highest values showed the highest (14.6%). S-Tyr was generally high in those with keratopathy, but those without keratopathy had similar elevated values. A similar pattern across centres was seen for body weight changes, with a statistically significant weight increase in nitisinone-treated patients at centres with lower u-urea24 values. Therefore, in nitisinone-treated patients, protein restriction led to increased body weight but may also have lowered the risk of developing keratopathies. If introduced, a protein-restricted diet should be supervised by a dietician and, when appropriate, include amino acid supplements deficient in tyrosine and phenylalanine, to avoid malnutrition and undesired weight increase.

Polyphenols as Prebiotics in the Management of High-Fat Diet-Induced Obesity: A Systematic Review of Animal Studies

Obesity is a disease growing at an alarming rate and numerous preclinical studies have proven the role of polyphenols in managing this disease. This systematic review explores the prebiotic effect of polyphenols in the management of obesity among animals fed on a high-fat diet. A literature search was carried out in PubMed, Scopus, CINAHL, Web of Science, and Embase databases following the PRISMA guidelines. Forty-four studies reported a significant reduction in obesity-related parameters. Most notably, 83% of the studies showed a decrease in either body weight/visceral adiposity/plasma triacylglyceride. Furthermore, 42 studies reported a significant improvement in gut microbiota (GM), significantly affecting the genera Akkermansia, Bacteroides, Blautia, Roseburia, Bifidobacteria, Lactobacillus, Alistipes, and Desulfovibrio. Polyphenols’ anti-obesity, anti-hyperglycaemic, and anti-inflammatory properties were associated with their ability to modulate GM. This review supports the notion of polyphenols as effective prebiotics in ameliorating HFD-induced metabolic derangements in animal models.

Path Analysis on Determinants of Childhood Obesity and Associated Risk Factors of Cardiovascular, Renal, and Hepatic Diseases: The CASPIAN-V Study

The interaction between several lifestyle and obesogenic environmental factors is considered as the main underlying factor for the escalating trend of childhood obesity and its adverse consequences. In this study, we assessed the mutual influence of lifestyle habits and body mass index (BMI) as well as risk factors for cardiometabolic, hepatic, and renal disorders to define the causality power of each item. This nationwide cross-sectional study was conducted as the fifth round of a school-based surveillance program. Overall, 14,800 students living in Iran were studied, and blood samples were obtained from 4,200 of them. Demographic factors, anthropometric and biochemical measures were used to define lifestyle-related latent variables as well as cardiac, renal, and hepatic risk indicators. Total, direct, and indirect effects between factors were analyzed using the standardized regression weights for each pathway. Data from 14,274 students (participation rate of 99%) and 3,843 blood samples were included. All of the latent variables had a significant direct effect on BMI, with the most potent effect of unhealthy nutrition (β ≅ 0.63) in boys and girls. BMI has significant direct effects on risk indicators of cardiovascular, renal, and hepatic diseases with the most powerful effect on cardiovascular risk factors (β ≅  − 0.08). The most important predisposing factor for obesity was unhealthy nutrition, whereas increased activity, adequate sleep, and better hygiene had protective roles. BMI shows the strongest association with indicator of cardiovascular diseases. These findings underscore the importance of implementing public health programs for the prevention of chronic noncommunicable diseases.

Stable isotopes in hair reveal dietary protein sources with links to socioeconomic status and health

Carbon and nitrogen isotope ratios in hair sampled from 65 communities across the central and intermountain regions of the United States and more intensively throughout 29 ZIP codes in the Salt Lake Valley, Utah, revealed a dietary divergence related to socioeconomic status as measured by cost of living, household income, and adjusted gross income. Corn-fed, animal-derived proteins were more common in the diets of lower socioeconomic status populations than were plant-derived proteins, with individual estimates of animal-derived protein diets as high as 75%; United States towns and cities averaged 57%. Similar patterns were seen across the socioeconomic status spectrum in the Salt Lake Valley. It is likely that corn-fed animal proteins were associated with concentrated animal-feeding operations, a common practice for industrial animal production in the United States today. Given recent studies highlighting the negative impacts of animal-derived proteins in our diets, hair carbon isotope ratios could provide an approach for scaling assessments of animal-sourced foods and health risks in communities across the United States.

Translation of Nutrient Level Recommendations to Control Serum Phosphate Into Food-Based Advice

The control of hyperphosphatemia is key to the management of chronic kidney disease mineral and bone disorder. Dietary restriction of phosphorus is essential to control hyperphosphatemia. Guidelines for chronic kidney disease and end-stage kidney disease generally provide high-level guidance on whether a nutrient should be restricted e.g, restrict dietary phosphorus. Dietitians translate such guidance into nutrient-based strategies and finally into food-based practical dietary advice for patients to follow. The practical aspects of dietary advice are not well described in the literature, neither are the challenges of concurrently altering 1 nutrient e.g., phosphorus while continuing to restrict others e.g., potassium, while maintaining overall nutritional adequacy and quality of life. In this article, we describe how we translated updated nutrient level recommendations into practical dietary advice to be delivered at the bedside.

Increased Expression of the Leptin Gene in Adipose Tissue of Patients with Chronic Kidney Disease-The Possible Role of an Abnormal Serum Fatty Acid Profile

Chronic kidney disease (CKD) is associated with an increased level of leptin and an abnormal fatty acid (FA) profile in the serum. However, there are no data on the associations between them, and the reason for increased serum levels in patients with CKD is not well elucidated. Recently, we found that a CKD-related abnormal FA profile caused significant changes in the expression of genes involved in lipid metabolism in hepatocytes. The aim of this study was to examine whether leptin gene expression in subcutaneous adipose tissue (SAT) of patients with CKD may contribute to increased serum levels of this adipokine and whether the abnormal serum FA profile observed in CKD patients has an impact on leptin gene expression in adipocytes. The FA profile was measured in serum samples from patients with CKD and controls by GC–MS. The relative mRNA levels of leptin were measured in SAT by Real-Time PCR. Moreover, the effect of the CKD-related abnormal FA profile on leptin gene expression was studied in in vitro cultured 3T3-L1 adipocytes. Patients with CKD had higher concentrations of serum leptin than controls and higher expression level of the leptin gene in SAT. They also had increased serum monounsaturated FAs and decreased polyunsaturated FAs. The incubation of adipocytes with FAs isolated from CKD patients resulted in an increase of the levels of leptin mRNA. Increased leptin gene expression in SAT may contribute to elevated concentrations of these adipokine in patients with CKD. CKD-related alterations of the FA profile may contribute to elevated serum leptin concentrations in patients with CKD by increasing the gene expression of this adipokine in SAT.

Targeting ROS and cPLA2/COX2 Expressions Ameliorated Renal Damage in Obese Mice with Endotoxemia

Obesity is associated with metabolic endotoxemia, reactive oxygen species (ROS), chronic inflammation, and obese kidney fibrosis. Although the fat-intestine-kidney axis has been documented, the pathomechanism and therapeutic targets of obese kidney fibrosis remain unelucidated. To mimic obese humans with metabolic endotoxemia, high-fat-diet-fed mice (HF group) were injected with lipopolysaccharide (LPS) to yield the obese kidney fibrosis-metabolic endotoxemia mouse model (HL group). Therapeutic effects of ROS, cytosolic phospholipases A2 (cPLA2) and cyclooxygenase-2 (COX-2) inhibitors were analyzed with a quantitative comparison of immunohistochemistry stains and morphometric approach in the tubulointerstitium of different groups. Compared with basal and HF groups, the HL group exhibited the most prominent obese kidney fibrosis, tubular epithelial lipid vacuoles, and lymphocyte infiltration in the tubulointerstitium. Furthermore, inhibitors of nonspecific ROS, cPLA2 and COX-2 ameliorated the above renal damages. Notably, the ROS-inhibitor-treated group ameliorated not only oxidative injury but also the expression of cPLA2 and COX-2, indicating that ROS functions as the upstream signaling molecule in the inflammatory cascade of obese kidney fibrosis. ROS acts as a key messenger in the signaling transduction of obese kidney fibrosis, activating downstream cPLA2 and COX-2. The given antioxidant treatment ameliorates obese kidney fibrosis resulting from a combined high-fat diet and LPS-ROS could serve as a potential therapeutic target of obese kidney fibrosis with metabolic endotoxemia.

Low Birth Weight, Blood Pressure and Renal Susceptibility

PURPOSE OF THE REVIEW

The purpose of this review is to highlight the clinical significance of increased renal risk that has its origins in fetal life. This review will also discuss the critical need to identify therapeutic interventions for use in a pregnancy complicated by placental dysfunction and intrauterine growth restriction that can mitigate the developmental origins of kidney disease without inflicting additional harm on the developing fetus.

RECENT FINDINGS

A reduction in nephron number is a contributory factor in the pathogenesis of hypertension and kidney disease in low birth weight individuals. Reduced nephron number may heighten susceptibility to a secondary renal insult, and recent studies suggest that perinatal history including birth weight should be considered in the assessment of renal risk in kidney donors. This review highlights current findings related to placental dysfunction, intrauterine growth restriction, increased risk for renal injury and disease, and potential therapeutic interventions.