Renal function following three distinct weight loss dietary strategies during 2 years of a randomized controlled trial

Fad diets for non-dialysis chronic kidney disease patients: Can "the miracle diet" be a threat?

In the pursuit of an effortless "miracle cure", there has been a significant increase in the proliferation of fad diets. These diets generally exclude a food group or macronutrients and may also restrict energy intake; they become popular quickly but often lack substantial scientific evidence to support their efficacy and safety. They only show short-term results rather than promoting a lifestyle change. Fad diets are nutritionally unbalanced and can be dangerous for some individuals. Most fad diets are generally restrictive in carbohydrates, high in protein, or unbalanced and have low energy intake, which can harm patients with early stages of chronic kidney damage (CKD) who need a low-protein diet with adequate energy intake. This narrative review discusses the risk of fad diet prescriptions for non-dialysis CKD patients.

A 6-Month mHealth Low-Carbohydrate Dietary Intervention Ameliorates Glycaemic and Cardiometabolic Risk Profile in People with Type 2 Diabetes

Aim: Mobile health (mHealth) applications have been reported to be effective in improving glycaemic control and cardiometabolic health, but mainly as part of shorter-term intervention studies. The aim of this study is to examine the effect of the ongoing Defeat Diabetes mHealth low-carbohydrate diet (LCD) intervention on clinical markers and cardiometabolic risk after 6 months of intervention. Methods: Data were collected via primary care physicians as part of routine T2D monitoring. These included HbA1c (primary outcome), blood pressure, blood lipids, and markers of kidney and liver function. Anthropometrics, as well as changes in the prescription of diabetes, hypertension, and dyslipidaemia medication, were also recorded. Calculated variables, total cholesterol to HDL-c, triglyceride to HDL-c, and waist to height ratios, were analysed to examine changes in cardiometabolic risk profile. Three-day food records were used to assess dietary intake and intervention adherence. Univariate regression models examined changes from baseline to 6 months. Results: Ninety-four participants remained in the study out of the ninety-nine at baseline (mean age 59 ± 11 years, 55 females). After 6 months of intervention, there were significant reductions in HbA1c by -1.0% (95% CI: -1.3 to -0.6), as well as in the liver enzymes ALT (-9.3 U/L 95% CI -16.3 to -2.4) and GGT (-18.8 U/L 95% CI: -31.4 to -6.3) across the cohort. In addition, there was a significant reduction in cardiometabolic risk, as measured by the calculated variables and a decrease in waist circumference (-4.6 cm 95% CI: -8.9 to -0.2). Conclusions: People with T2D receiving LCD education and resources through the Defeat Diabetes mHealth app (version 3.3.8) improved their glycaemic control after 6 months of intervention. Cardiometabolic risk profile and liver function also showed significant improvement. These findings indicate that the use of an LCD digital app is a valuable adjunct in the management of T2D.

From Adipose to Ailing Kidneys: The Role of Lipid Metabolism in Obesity-Related Chronic Kidney Disease

Obesity has emerged as a significant public health crisis, closely linked to the pathogenesis and progression of chronic kidney disease (CKD). This review explores the intricate relationship between obesity-induced lipid metabolism disorders and renal health. We discuss how excessive free fatty acids (FFAs) lead to lipid accumulation in renal tissues, resulting in cellular lipotoxicity, oxidative stress, and inflammation, ultimately contributing to renal injury. Key molecular mechanisms, including the roles of transcriptional regulators like PPARs and SREBP-1, are examined for their implications in lipid metabolism dysregulation. The review also highlights the impact of glomerular and tubular lipid overload on kidney pathology, emphasizing the roles of podocytes and tubular cells in maintaining kidney function. Various therapeutic strategies targeting lipid metabolism, including pharmacological agents such as statins and SGLT2 inhibitors, as well as lifestyle modifications, are discussed for their potential to mitigate CKD progression in obese individuals. Future research directions are suggested to better understand the mechanisms linking lipid metabolism to kidney disease and to develop personalized therapeutic approaches. Ultimately, addressing obesity-related lipid metabolism disorders may enhance kidney health and improve outcomes for individuals suffering from CKD.

The Kidney in Obesity: Current Evidence, Perspectives and Controversies

PURPOSE OF REVIEW

As obesity and chronic kidney disease (CKD) remain a public health issue, we aim to elaborate on their complex relationship regarding pathogenetic mechanisms and therapeutic potential as well. The purpose of this review is to enhance our understanding of the interplay between obesity and CKD in order to timely diagnose and treat obesity-related CKD.

RECENT FINDINGS

Obesity and CKD pose significant intertwined challenges to global health, affecting a substantial portion of the population worldwide. Obesity is recognized as an independent risk factor, intricately contributing to CKD pathogenesis through mechanisms such as lipotoxicity, chronic inflammation, and insulin resistance. Recent evidence highlights additional factors including hemodynamic changes and intestinal dysbiosis that exacerbate kidney dysfunction in obese individuals, leading to histologic alterations known as obesity-related glomerulopathy (ORG). This narrative review synthesizes current knowledge on the prevalence, pathophysiology, clinical manifestations, and diagnostic strategies of obesity-related kidney disease. Furthermore, it explores mechanistic insights to delineate current therapeutic approaches, future directions for managing this condition and controversies. By elucidating the multifaceted interactions between obesity and kidney health, this review aims to inform clinical practice and stimulate further research to address this global health epidemic effectively.

Nutritional assessment and medical dietary therapy for management of obesity in patients with non-dialysis chronic kidney disease: a practical guide for endocrinologist, nutritionists and nephrologists. A consensus statement from the Italian society of endocrinology (SIE), working group of the club nutrition-hormones and metabolism; the Italian society of nutraceuticals (SINut), club ketodiets and nutraceuticals "KetoNut-SINut"; and the Italian society of nephrology (SIN)

PURPOSE

Chronic kidney disease (CKD) is a serious health concern with an estimated prevalence of about 13.4% worldwide. It is cause and consequence of various comorbidities, including cardiovascular diseases. In parallel, common pathological conditions closely related to ageing and unhealthy dietary habits increase the risk of CKD development and progression, including type 2 diabetes and obesity. Among these, obesity is either independent risk factor for new onset kidney disease or accelerates the rate of decline of kidney function by multiple mechanisms. Therefore, the role of diets aimed at attaining weight loss in patients with obesity is clearly essential to prevent CKD as to slow disease progression. Various dietary approaches have been licensed for the medical dietary therapy in CKD, including low-protein diet and Mediterranean diet. Interestingly, emerging evidence also support the use of low-carbohydrate/ketogenic diet (LCD/KD) in these patients. More specifically, LCD/KDs may efficiently promote weight loss, improve metabolic parameters, and reduce inflammation and oxidative stress, resulting in a dietary strategy that act globally in managing collateral conditions that are directly and indirectly related to the kidney function.

CONCLUSION

This consensus statement from the Italian Society of Endocrinology (SIE), working group of the Club Nutrition - Hormones and Metabolism; the Italian Society of Nutraceuticals (SINut), Club Ketodiets and Nutraceuticals "KetoNut-SINut"; and the Italian Society of Nephrology (SIN) is intended to be a guide for Endocrinologist, Nutritionists and Nephrologist who deal with the management of patients with obesity with non-dialysis CKD providing a practical guidance on assessing nutritional status and prescribing the optimal diet in order to best manage obesity to prevent CKD and its progression to dialysis.

Approaches to patients with obesity and CKD: focus on nutrition and surgery

Obesity is recognized as a public health challenge. During the last three decades, the global age-standardized prevalence increased from 8.8% to 18.5% in women and from 4.8% to 14.0% in men, with an absolute current number of 878 million obese subjects. Obesity significantly increases per se the risk of developing disability and chronic diseases, including chronic kidney disease (CKD). Specifically, obesity acts as a major, modifiable cause of CKD onset and progression toward kidney failure; as such, it is considered by the International Society of Nephrology a major health priority. This review analyses the effectiveness, safety and practicability of non-pharmacological anti-obesity interventions in CKD as the different patient phenotypes that may take advantage of personalized approaches.

Exploring Adiposity and Chronic Kidney Disease: Clinical Implications, Management Strategies, Prognostic Considerations

Obesity poses a significant and growing risk factor for chronic kidney disease (CKD), requiring comprehensive evaluation and management strategies. This review explores the intricate relationship between obesity and CKD, emphasizing the diverse phenotypes of obesity, including sarcopenic obesity and metabolically healthy versus unhealthy obesity, and their differential impact on kidney function. We discuss the epidemiological evidence linking elevated body mass index (BMI) with CKD risk while also addressing the paradoxical survival benefits observed in obese CKD patients. Various measures of obesity, such as BMI, waist circumference, and visceral fat assessment, are evaluated in the context of CKD progression and outcomes. Mechanistic insights into how obesity promotes renal dysfunction through lipid metabolism, inflammation, and altered renal hemodynamics are elucidated, underscoring the role of adipokines and the renin-angiotensin-aldosterone system. Furthermore, the review examines current strategies for assessing kidney function in obese individuals, including the strengths and limitations of filtration markers and predictive equations. The management of obesity and associated comorbidities like arterial hypertension, type 2 diabetes mellitus, and non-alcoholic fatty liver disease in CKD patients is discussed. Finally, gaps in the current literature and future research directions aimed at optimizing the management of obesity-related CKD are highlighted, emphasizing the need for personalized therapeutic approaches to mitigate the growing burden of this intertwined epidemic.

High Protein Diets and Glomerular Hyperfiltration in Athletes and Bodybuilders: Is Chronic Kidney Disease the Real Finish Line?

Several observational and experimental studies in humans have suggested that high protein intake (PI) causes intraglomerular hypertension leading to hyperfiltration. This phenomenon results in progressive loss of renal function with long-term exposure to high-protein diets (HPDs), even in healthy people. The recommended daily allowance for PI is 0.83 g/kg per day, which meets the protein requirement for approximately 98% of the population. A HPD is defined as a protein consumption > 1.5 g/kg per day. Athletes and bodybuilders are encouraged to follow HPDs to optimize muscle protein balance, increase lean body mass, and enhance performance. A series of studies in resistance-trained athletes looking at HPD has been published concluding that there are no harmful effects of HPD on renal health. However, the aim of these studies was to evaluate body composition changes and they were not designed to assess safety or kidney outcomes. Here we review the effects of HPD on kidney health in athletes and healthy individuals with normal kidney function.

Dietary counseling, meal patterns, and diet quality in patients with type 2 diabetes mellitus with/without chronic kidney disease

BACKGROUND

Aim to this study is to investigate the association of Dietary Counseling, Meal Patterns, and Diet Quality (DietQ) in Patients with Type 2 Diabetes Mellitus (T2DM) with/without chronic kidney disease (CKD) in primary healthcare.

METHODS

Cross-sectional study acquired data on dietary counseling and meal patterns by direct interview with a food-frequency questionnaire and one 24-h food-recall. The Healthy Eating Index (HEI) was used to classify DietQ ["good" DietQ (GDietQ, score ≥ 80) and "poor" DietQ (PDietQ, score < 80)].

PARTICIPANTS/SETTING

This study included 705 patients with T2DM: 306 with normal kidney function; 236 with early nephropathy, and 163 with overt nephropathy (ON).

STATISTICAL ANALYSES PERFORMED

Multivariate linear-regression models for predicting HEI and χ2 tests for qualitative variables and one-way ANOVA for quantitative variables were employed. Mann-Whitney U and independent Student t were performed for comparisons between GDietQ and PDietQ.

RESULTS

Only 18 % of the population was classified as GDietQ. Patients with ON and PDietQ vs. with GDietQ received significantly less dietary counseling from any health professional in general (45 % vs 72 %, respectively), or from any nutrition professional (36 % vs. 61 %, respectively). A better HEI was significantly predicted (F = 42.01; p = 0.0001) by lower HbA1C (β -0.53, p = 0.0007) and better diet diversity (β 8.09, p = 0.0001).

CONCLUSIONS

Patients with more advanced stages of CKD had less nutritional counseling and worse dietary patterns, as well as more frequent PDietQ. Our findings reinforce the need for dietitians and nutritionists in primary healthcare to provide timely nutritional counseling.

Potential Add-On Benefits of Dietary Intervention in the Treatment of Autosomal Dominant Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited cause of renal failure. The pathogenesis of the disease encompasses several pathways and metabolic alterations, including the hyperactivation of mTOR and suppression of AMPK signaling pathways, as well as mitochondrial dysfunction. This metabolic reprogramming makes epithelial cyst-lining cells highly dependent on glucose for energy and unable to oxidize fatty acids. Evidence suggests that high-carbohydrate diets may worsen the progression of ADPKD, providing the rationale for treating ADPKD patients with calorie restriction and, in particular, with ketogenic dietary interventions, already used for other purposes such as in overweight/obese patients or in the treatment of refractory epilepsy in children. Preclinical studies have demonstrated that calorie restriction may prevent and/or slow disease progression by inducing ketosis, particularly through increased beta-hydroxybutyrate (BHB) levels, which may modulate the metabolic signaling pathways altered in ADKPK. In these patients, although limited, ketogenic intervention studies have shown promising beneficial effects. However, larger and longer randomized controlled trials are needed to confirm their tolerability and safety in long-term maintenance and their additive role in the therapy of polycystic kidney disease.

Cardiometabolic comorbidities and complications of obesity and chronic kidney disease (CKD)

Obesity and chronic kidney disease are two ongoing progressive clinical pandemics of major public health and clinical care significance. Because of their growing prevalence, chronic indolent course and consequent complications both these conditions place significant burden on the health care delivery system especially in developed countries like the United States. Beyond the chance coexistence of both of these conditions in the same patient based on high prevalence it is now apparent that obesity is associated with and likely has a direct causal role in the onset, progression and severity of chronic kidney disease. The causes and underlying pathophysiology of this are myriad, complicated and multi-faceted. In this review, continuing the theme of this special edition of the journal on " The Cross roads between Endocrinology and Nephrology" we review the epidemiology of obesity related chronic kidney disease (ORCKD), and its various underlying causes and pathophysiology. In addition, we delve into the consequent comorbidities and complications associated with ORCKD with particular emphasis on the cardio metabolic consequences and then review the current body of evidence for available strategies for chronic kidney disease modulation in ORCKD as well as the potential unique role of weight reduction and management strategies in its improvement and risk reduction.

The case for a ketogenic diet in the management of kidney disease

Ketogenic diets have been widely used for weight loss and are increasingly used in the management of type 2 diabetes. Despite evidence that ketones have multiple positive effects on kidney function, common misconceptions about ketogenic diets, such as high protein content and acid load, have prevented their widespread use in individuals with impaired kidney function. Clinical trial evidence focusing on major adverse kidney events is sparse. The aim of this review is to explore the effects of a ketogenic diet, with an emphasis on the pleiotropic actions of ketones, on kidney health. Given the minimal concerns in relation to the potential renoprotective effects of a ketogenic diet, future studies should evaluate the safety and efficacy of ketogenic interventions in kidney disease.

Expert consensus on nutrition and lower-carbohydrate diets: An evidence- and equity-based approach to dietary guidance

There is a substantial body of clinical evidence supporting the beneficial effects of lower-carbohydrate dietary patterns on multiple established risk factors associated with insulin resistance and cardiovascular diseases in adult populations. Nutrition and health researchers, clinical practitioners, and stakeholders gathered for, "The Scientific Forum on Nutrition, Wellness, and Lower-Carbohydrate Diets: An Evidence- and Equity-Based Approach to Dietary Guidance" to discuss the evidence base around lower-carbohydrate diets, health outcomes, and dietary guidance. Consensus statements were agreed upon to identify current areas of scientific agreement and spotlight gaps in research, education, and practice to help define and prioritize future pathways. Given the evidence base and considering that most American adults are living with at least one nutrition-related chronic disease, there was consensus that including a lower-carbohydrate dietary pattern as one part of the Dietary Guidelines for Americans could help promote health equity among the general population.

The effect of diet-induced weight loss on circulating homocysteine levels in people with obesity and type 2 diabetes

BACKGROUND/AIMS

Having type 2 diabetes (T2D) in combination with being overweight results in an additional increase in cardiovascular disease (CVD) risk. In addition, T2D and obesity are associated with increased levels of total homocysteine (tHcy), possibly contributing to the CVD risk. Weight loss dieting has positive effects on several CVD risk factors, but whether it affects tHcy remains unclear. Therefore, the aim of this study was to determine the effect of a calorie restricted diet on tHcy in overweight people with T2D.

METHODS

In this post-hoc analysis of the POWER study, adults with T2D and a BMI greater than 27 kg/m² were included from the outpatient diabetes clinic of the Erasmus Medical Center, Rotterdam. The patients were subjected to a very low-calorie diet with fortified meal replacements for 20 weeks. Before and after this intervention, blood samples were collected to measure tHcy and other CVD risk factors like glycaemic and lipid parameters.

RESULTS

161 overweight participants with T2D were included, with a mean age of 54 years (range 26-74), mean weight of 104.6 ± 19.9 kg and mean HbA1c of 62.7 ± 14.3 mmol/mol. At baseline, men displayed higher tHcy than women, and tHcy level was positively correlated with body weight and triglyceride levels, while it was negatively correlated with renal function and HDL cholesterol. During the intervention, bodyweight was reduced by a mean of 9.7% (from 104.6 ± 19.9 to 94.5 ± 18.1 kg p < 0.001), and all measured glycaemic and lipid blood parameters improved significantly. However, tHcy remained unchanged (from 12.1 ± 4.1 to 12.1 ± 4.2 umol/L, p = 0.880). The change in tHcy during the intervention was negatively associated with the change in weight and BMI (p = 0.01 and p = 0.008, respectively). People who lost < 10 kg (n = 92) had a mean tHcy change of -0.47 umol/L, while people who lost more than ≥ 10 kg (n = 69) had a mean tHcy change of 0.60 umol/L (p = 0.021).

CONCLUSION

In conclusion, our data show that a calorie restricted diet does not affect tHcy in people with T2D and obesity, despite the use of meal replacements fortified with folic acid and vitamin B12. Our data showed a negative correlation between change in tHcy levels and weight loss, suggesting that people who lost more weight (> 10 kg) showed an increase in tHcy. Future studies should explore the potential increase in tHcy induced by weight loss dieting and target the question if tHcy reduction strategies during weight loss could be clinically beneficial.

Ketogenic metabolic therapy for chronic kidney disease - the pro part

Ketogenic metabolic therapy (KMT) is a medical nutrition therapy to address certain health and disease conditions. It is increasingly used for many non-communicable diseases that are rooted in abnormal metabolic health. Since chronic kidney disease (CKD) is commonly caused by overnutrition leading to hyperglycemia, insulin resistance and diabetes mellitus, the carbohydrate restriction inherent in KMT may offer a therapeutic option. Numerous studies have found that various forms of KMT are safe for individuals with CKD and may lead to improvement of renal function. This is in contrast to the current standard pharmacological approach to CKD that only slows the relentless progression towards renal failure. Kidney care providers, including physicians and dietitians, are usually not aware of non-standard dietary interventions, including KMT, and often criticize KMT due to common misconceptions and uncertainty about the underlying science, including the common misconception that KMT must involve high protein or meat consumption. This review article discusses the rationales for using KMT, including plant-dominant KMT, for treatment of CKD, clarifies common misconceptions, summarizes the results of clinical studies and discusses why KMT is emerging as an effective medical nutrition therapy (MNT) to consider for patients with kidney disease. KMT, including its plant-dominant versions, can expand a practitioner's kidney health toolbox and will likely become a first-line therapy for CKD in certain CKD-associated conditions such as obesity, metabolic syndrome and polycystic kidney disease.

Cardiovascular-Kidney-Metabolic Health: A Presidential Advisory From the American Heart Association

Cardiovascular-kidney-metabolic health reflects the interplay among metabolic risk factors, chronic kidney disease, and the cardiovascular system and has profound impacts on morbidity and mortality. There are multisystem consequences of poor cardiovascular-kidney-metabolic health, with the most significant clinical impact being the high associated incidence of cardiovascular disease events and cardiovascular mortality. There is a high prevalence of poor cardiovascular-kidney-metabolic health in the population, with a disproportionate burden seen among those with adverse social determinants of health. However, there is also a growing number of therapeutic options that favorably affect metabolic risk factors, kidney function, or both that also have cardioprotective effects. To improve cardiovascular-kidney-metabolic health and related outcomes in the population, there is a critical need for (1) more clarity on the definition of cardiovascular-kidney-metabolic syndrome; (2) an approach to cardiovascular-kidney-metabolic staging that promotes prevention across the life course; (3) prediction algorithms that include the exposures and outcomes most relevant to cardiovascular-kidney-metabolic health; and (4) strategies for the prevention and management of cardiovascular disease in relation to cardiovascular-kidney-metabolic health that reflect harmonization across major subspecialty guidelines and emerging scientific evidence. It is also critical to incorporate considerations of social determinants of health into care models for cardiovascular-kidney-metabolic syndrome and to reduce care fragmentation by facilitating approaches for patient-centered interdisciplinary care. This presidential advisory provides guidance on the definition, staging, prediction paradigms, and holistic approaches to care for patients with cardiovascular-kidney-metabolic syndrome and details a multicomponent vision for effectively and equitably enhancing cardiovascular-kidney-metabolic health in the population.

Animal Protein Intake and Possible Cardiovascular Risk in People With Chronic Kidney Disease: Mechanisms and Evidence

Individuals with chronic kidney disease (CKD) have an increased risk of cardiovascular disease (CVD), and the kidney function is a critical determinant of this risk. CKD is also a major cause of complications and disease progression in patients with CVD. Practice guidelines suggest that CVD risk in CKD patients can be managed through healthy lifestyle and dietary behaviors. Assessing the impact of diet on heart and kidney health is complex because numerous bioactive compounds from diet may contribute to or prevent CVD or CKD via a myriad of pathways and mechanisms. The objective of this review was to provide a discussion of the mechanisms and evidence linking protein-rich foods and CVD risk in people with CKD. This review highlights the current evidence-based strategies for primary CKD prevention that incorporate a healthy dietary pattern, while tertiary prevention strategies focus on avoiding excess protein and reducing dietary acid load. The effect of protein restriction for improving CVD and CKD outcomes is conflicting; however, these approaches show no negative effects on kidney health. Low-protein and very low-protein diets are promising interventions for reducing the progression of CKD and CVD. Animal-sourced protein may be more detrimental to kidney health than plant-sourced protein due to specific acid load, amino acid composition, generation of uremic toxins, accompanying saturated fat content, low fiber composition, and higher generation of advanced glycation end-products. There are no one-size fits all nutrition prescriptions. Personalized nutrition interventions that target the unique risk factors for CVD associated with reduced kidney function are required to improve the health of people living with CKD.

The Fat Kidney

PURPOSE OF REVIEW

The purpose of this review is to summarize the current evidence on the role of obesity in the development and progression of chronic kidney disease and the current evidence on nutritional, pharmacological, and surgical strategies for the management of individuals with obesity and chronic kidney disease.

RECENT FINDINGS

Obesity can hurt the kidney via direct pathways, through the production of pro-inflammatory adipocytokines, and indirectly due to systemic complications of obesity, including type 2 diabetes mellitus and hypertension. In particular, obesity can damage the kidney through alterations in renal hemodynamics resulting in glomerular hyperfiltration, proteinuria and, finally, impairment in glomerular filtratation rate. Several strategies are available for weight loss and maintenance, such as the modification of lifestyle (diet and physical activity), anti-obesity drugs, and surgery therapy, but there are no clinical practice guidelines to manage subjects with obesity and chronic kidney disease. Obesity is an independent risk factor for the progression of chronic kidney disease. In subjects with obesity, weight loss can slow down the progression of renal failure with a significant reduction in proteinuria and improvement in glomerular filtratation rate. Specifically, in the management of subjects with obesity and chronic renal disease, it has been shown that bariatric surgery can prevent the decline in renal function, while further clinical studies are needed to evaluate the efficacy and safety on the kidney of weight reducing agents and the very low-calorie ketogenic diet.

Contributions of obesity to kidney health and disease: insights from Mendelian randomization and the human kidney transcriptomics

AIMS

Obesity and kidney diseases are common complex disorders with an increasing clinical and economic impact on healthcare around the globe. Our objective was to examine if modifiable anthropometric obesity indices show putatively causal association with kidney health and disease and highlight biological mechanisms of potential relevance to the association between obesity and the kidney.

METHODS AND RESULTS

We performed observational, one-sample, two-sample Mendelian randomization (MR) and multivariable MR studies in ∼300 000 participants of white-British ancestry from UK Biobank and participants of predominantly European ancestry from genome-wide association studies. The MR analyses revealed that increasing values of genetically predicted body mass index and waist circumference were causally associated with biochemical indices of renal function, kidney health index (a composite renal outcome derived from blood biochemistry, urine analysis, and International Classification of Disease-based kidney disease diagnoses), and both acute and chronic kidney diseases of different aetiologies including hypertensive renal disease and diabetic nephropathy. Approximately 13-16% and 21-26% of the potentially causal effect of obesity indices on kidney health were mediated by blood pressure and type 2 diabetes, respectively. A total of 61 pathways mapping primarily onto transcriptional/translational regulation, innate and adaptive immunity, and extracellular matrix and metabolism were associated with obesity measures in gene set enrichment analysis in up to 467 kidney transcriptomes.

CONCLUSIONS

Our data show that a putatively causal association of obesity with renal health is largely independent of blood pressure and type 2 diabetes and uncover the signatures of obesity on the transcriptome of human kidney.

Retrospective analysis on the effect of Reverse Diabetes2 Now on kidney function in patients with type 2 diabetes with impaired kidney function

Objective

Type 2 diabetes is one of the main causes of kidney damage. Recent intervention studies suggest that the progression of type 2 diabetes can be halted, or even brought into remission by lifestyle interventions. In a pragmatic trial, the Reverse Diabetes2 Now programme (RD2N, NL: Keer Diabetes2 Om), a multicomponent lifestyle intervention, reduced the need for bloodglucose lowering medications up to 24 months.

Research design and methods

Here, we retrospectively investigate the effect of RD2N on markers of kidney function in patients selected for impaired kidney function at baseline (eGFR <70 mL/min/1.73 m² (n=45). Baseline data were retrieved from the intervention database and follow-up data on renal markers were collected from routine medical records. Wilcoxon non-parametric tests were used to assess changes over 6 and 12 months.

Results

After 6 months median eGFR increased significantly from 62.0 (IQR 55.5-65.0) to 69.0 (IQR 55.0-76.5) mL/min/1.73 m² (p=0.002). Median albumin/creatinine ratio (n=26) remained within the normal range (<3 mg/mmol). The effect on eGFR was similar after exclusion of patients in whom medication was changed (median eGFR 62.0 ((IQR 59.5-66.0) to 69.0 (IQR 60.0-77.0) mL/min/1.73 m², p=0.006, n=29), suggesting that the effect on eGFR is not related to medication changes. At 12 months, eGFR was not significantly changed (n=22, median eGFR 63.5 mL/min/1.73 m² (IQR 58.5-71.0), p=0.067).

Conclusions

The retrospective nature of this study and the despite guidelines limited availability of renal markers in routine type 2 diabetes care are limiting. Nevertheless, these data support a favourable effect of RD2N on renal function. Further research, with proper documentation of renal function, urinary protein excretion and dietary intake, is needed to substantiate these results, ideally in a large-scale prospective cohort study.

Prospective associations between a priori dietary patterns adherence and kidney function in an elderly Mediterranean population at high cardiovascular risk

PURPOSE

To assess the association between three different a priori dietary patterns adherence (17-item energy reduced-Mediterranean Diet (MedDiet), Trichopoulou-MedDiet and Dietary Approach to Stop Hypertension (DASH)), as well as the Protein Diet Score and kidney function decline after one year of follow-up in elderly individuals with overweight/obesity and metabolic syndrome (MetS).

METHODS

We prospectively analyzed 5675 participants (55-75 years) from the PREDIMED-Plus study. At baseline and at one year, we evaluated the creatinine-based estimated glomerular filtration rate (eGFR) and food-frequency questionnaires-derived dietary scores. Associations between four categories (decrease/maintenance and tertiles of increase) of each dietary pattern and changes in eGFR (ml/min/1.73m2) or ≥ 10% eGFR decline were assessed by fitting multivariable linear or logistic regression models, as appropriate.

RESULTS

Participants in the highest tertile of increase in 17-item erMedDiet Score showed higher upward changes in eGFR (β: 1.87 ml/min/1.73m2; 95% CI: 1.00-2.73) and had lower odds of ≥ 10% eGFR decline (OR: 0.62; 95% CI: 0.47-0.82) compared to individuals in the decrease/maintenance category, while Trichopoulou-MedDiet and DASH Scores were not associated with any renal outcomes. Those in the highest tertile of increase in Protein Diet Score had greater downward changes in eGFR (β: - 0.87 ml/min/1.73m2; 95% CI: - 1.73 to - 0.01) and 32% higher odds of eGFR decline (OR: 1.32; 95% CI: 1.00-1.75).

CONCLUSIONS

Among elderly individuals with overweight/obesity and MetS, only higher upward change in the 17-item erMedDiet score adherence was associated with better kidney function after one year. However, increasing Protein Diet Score appeared to have an adverse impact on kidney health.

TRIAL REGISTRATION NUMBER

ISRCTN89898870 (Data of registration: 2014).

New approaches in the nutritional treatment of advanced chronic kidney disease

INTRODUCTION

Patients with advanced chronic kidney disease (ACKD) have a high prevalence of malnutrition. The dietary restrictions that we usually apply in terms of macro and micronutrients force our patients to follow dietary guidelines that deviate from healthy patterns.

OBJETIVES

To determine if a personalized nutritional intervention program, minimizing the usual restrictions would be justified in case it improved the evolution of kidney disease compared to standard treatment.

SECUNDARY OBJETIVES

To determine changes in nutrient intakes and in anthropometric and biochemical parameters, as well as quantify episodes of hyperkalemia.

MATERIAL AND METHODS

A single-center, randomized and controlled educational intervention clinical trial was conduct in patients from the ERCA outpatients clinic at the Complejo Hospitalario Universitario de Albacete. 75 patients were included, assigning 35 to a Control group and 40 to the Intervention group with 1-year follow-up. The nutritional status was determined using anthropometric data, body composition by Bioimpedance, blood and urine biochemical parameters and a 24-h recall questionnaire. The nutritional intervention was carried out in three different ways: individual, collective and telephone recall.

RESULTS

At the beginning of the study, the BMI showed a situation of weight excess with a mean of 28.83 kg/m² (5.4) in men and 26.96 kg/m² (4.09) in women. 70% of our patients had overweight. The abdominal circumference was 105.3 cm (10.2) and 92.3 cm (13.7) for men and women respectively without significant changes throughout the study. The percentage of fat mass (FM) was high in both groups for men and women throughout the study. We did not find biochemical parameters of malnutrition and only significant differences were observed in glomerular filtration rate (GFR), which increased in the intervention group. No patient presented any episodes of hyperkalemia during the study. The energy intake in both groups showed an inadequate distribution of macronutrients with a poor intake of carbohydrates (CH) that was supplemented with an excess of fat. In the case of micronutrients, we did observe an increase in potassium and fiber intakes with a decrease in sodium and phosphorus in the intervention group.

CONCLUSIONS

Malnutrition is not exclusively an intake defficit and encompasses both the problems derived from a deficit and an excess of nutrients intake. Un to 70% of our patients showed weight excess and a fat mass higher than desirable. The implementation of an individualized nutritional education program, including a vegetables and fiber rich diet, less atherogenic, not only did not cause electrolyte alterations but also slowed the progression of kidney disease.

High-calorie diet results in reversible obesity-related glomerulopathy in adult zebrafish regardless of dietary fat

Obesity is a risk factor for the development of kidney disease. The role of diet in this association remains undetermined, in part due to practical limitations in studying nutrition in humans. In particular, the relative importance of calorie excess versus dietary macronutrient content is poorly understood. For example, it is unknown if calorie restriction modulates obesity-related kidney pathology. To study the effects of diet-induced obesity in a novel animal model, we treated zebrafish for 8 wk with diets varied in both calorie and fat content. Kidneys were evaluated by light and electron microscopy. We evaluated glomerular filtration barrier function using a dextran permeability assay. We assessed the effect of diet on podocyte sensitivity to injury using an inducible podocyte injury model. We then tested the effect of calorie restriction on the defects caused by diet-induced obesity. Fish fed a high-calorie diet developed glomerulomegaly (mean: 1,211 vs. 1,010 µm2 in controls, P = 0.007), lower podocyte density, foot process effacement, glomerular basement membrane thickening, tubular enlargement (mean: 1,038 vs. 717 µm2 in controls, P < 0.0001), and ectopic lipid deposition. Glomerular filtration barrier dysfunction and increased susceptibility to podocyte injury were observed with high-calorie feeding regardless of dietary fat content. These pathological changes resolved with 4 wk of calorie restriction. Our findings suggest that calorie excess rather than dietary fat drives obesity-related kidney dysfunction and that inadequate podocyte proliferation in response to glomerular enlargement may cause podocyte dysfunction. We also demonstrate the value of zebrafish as a novel model for studying diet in obesity-related kidney disease.NEW & NOTEWORTHY Obesity is a risk factor for kidney disease. The role of diet in this association is difficult to study in humans. In this study, zebrafish fed a high-calorie diet, regardless of fat macronutrient composition, developed glomerulomegaly, foot process effacement, and filtration barrier dysfunction, recapitulating the changes seen in humans with obesity. Calorie restriction reversed the changes. This work suggests that macronutrient composition may be less important than total calories in the development of obesity-related kidney disease.

Adherence to the Dutch healthy diet index and change in glycemic control and cardiometabolic markers in people with type 2 diabetes

Purpose

To investigate whether adherence to the Dutch Healthy Diet index 2015 (DHD15-index) is associated with change in glycemic control and cardio-metabolic markers over two-year follow-up in people with type 2 diabetes (T2D).

Methods

This prospective cohort study included 1202 individuals with T2D (mean age 68.7 ± 9.0 years; 62.5% male; mean HbA1c 53.8 ± 11.7 mmol/mol) from the Diabetes Care System cohort. Baseline dietary intake was assessed using a validated food frequency questionnaire, and adherence to the DHD15-index was estimated (range 0–130). HbA1c, fasting glucose, blood lipids (HDL and LDL cholesterol, cholesterol ratio), blood pressure, estimated glomerular filtration rate (eGFR), and BMI were measured at baseline, and after one- and two-year follow-up. Linear mixed model analyses were conducted to examine the associations between adherence to the DHD15-index and glycemic control and the cardio-metabolic outcomes, adjusting for energy intake, sociodemographic and lifestyle characteristics, and medication.

Results

Highest adherence (T3) to the DHD15-index was not associated with change in HbA1c, compared to lowest adherence (T1) [β_T3vsT1: 0.62 mmol/mol (− 0.94; 2.19), P_trend = 0.44]. There was a non-linear association with fasting glucose, where moderate adherence (T2) was associated with a decrease in fasting glucose [β_T2vsT1: − 0.29 mmol/L (− 0.55; − 0.03), P_trend = 0.30]. Higher adherence to the DHD15-index was associated with a decrease in BMI [β_10point: − 0.41 kg/m² (− 0.60; − 0.21), P_trend < 0.001], but not with blood lipids, blood pressure or kidney function.

Conclusion

In this well-controlled population of people with T2D, adherence to the DHD15-index was associated with a decrease in BMI, but not with change in glycemic control or other cardio-metabolic parameters.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-022-02847-6.

Nutrition and physical activity: An Obesity Medicine Association (OMA) Clinical Practice Statement 2022

Background

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) on Nutrition and Physical Activity provides clinicians an overview of nutrition and physical activity principles applicable to the care of patients with increased body fat, especially those with adverse fat mass and adiposopathic metabolic consequences.

Methods

The scientific information and clinical guidance is based upon referenced evidence and derived from the clinical perspectives of the authors.

Results

This OMA CPS on Nutrition and Physical Activity provides basic clinical information regarding carbohydrates, proteins, fats (including trans fats, saturated fats, polyunsaturated fats, and monounsaturated fats), general principles of healthful nutrition, nutritional factors associated with improved health outcomes, and food labels. Included are the clinical implications of isocaloric substitution of refined carbohydrates with saturated fats and vice-versa, as well as definitions of low-calorie, very low-calorie, carbohydrate-restricted, and fat-restricted dietary intakes. Specific dietary plans discussed include carbohydrate-restricted diets, fat-restricted diets, very low-calorie diets, the Mediterranean diet, Therapeutic Lifestyle diet, Dietary Approaches to Stop Hypertension (DASH), ketogenic (modified Atkins) diet, Ornish diet, Paleo diet, vegetarian or vegan diet (whole food/plant-based), intermittent fasting/time restricted feeding, and commercial diet programs. This clinical practice statement also examines the health benefits of physical activity and provides practical pre-exercise medical evaluation guidance as well as suggestions regarding types and recommended amounts of dynamic (aerobic) training, resistance (anaerobic) training, leisure time physical activity, and non-exercise activity thermogenesis (NEAT). Additional guidance is provided regarding muscle physiology, exercise prescription, metabolic equivalent tasks (METS), and methods to track physical activity progress.

Conclusion

This Obesity Medicine Association Clinical Practice Statement on Nutrition and Physical Activity provides clinicians an overview of nutrition and physical activity. Implementation of appropriate nutrition and physical activity in patients with pre-obesity and/or obesity may improve the health of patients, especially those with adverse fat mass and adiposopathic metabolic consequences.

Renal function in patients following a low carbohydrate diet for type 2 diabetes: a review of the literature and analysis of routine clinical data from a primary care service over 7 years

PURPOSE OF REVIEW

People with T2 Diabetes (T2D) who follow a low carbohydrate diet (LCD) may increase their dietary protein intake. Dietary protein can modulate renal function so there is debate about its role in renal disease. There is concern that higher protein intakes may promote renal damage, and that LCDs themselves may impact on cardiovascular risk. We review the evidence around LCDs, renal and cardiovascular risk factors and compare to results obtained in a real-world, primary care setting.

RECENT FINDINGS

Chronic kidney disease (CKD) is a well-recognised microvascular complication of T2D caused in part by; chronically increased glomerular pressure, hyperfiltration, increased blood pressure and advanced glycation end products. Hyperglycemia can be seen as central to all of these factors. A LCD is an effective first step in its correction as we demonstrate in our real-world cohort.

SUMMARY

We found evidence that LCDs for people with T2D may improve many renal and cardiovascular risk factors. In our own LCD cohort of 143 patients with normal renal function or only mild CKD, over an average of 30 months the serum creatinine improved by a significant mean of 4.7 (14.9) μmol/L. What remains to be shown is the effect of the approach on people with T2D and moderate/severe CKD.

Ketogenic dietary interventions in autosomal dominant polycystic kidney disease-a retrospective case series study: first insights into feasibility, safety and effects

Background

Our laboratory published the first evidence that nutritional ketosis, induced by a ketogenic diet (KD) or time-restricted diet (TRD), ameliorates disease progression in polycystic kidney disease (PKD) animal models. We reasoned that, due to their frequent use for numerous health benefits, some autosomal dominant PKD (ADPKD) patients may already have had experience with ketogenic dietary interventions (KDIs). This retrospective case series study is designed to collect the first real-life observations of ADPKD patients about safety, feasibility and possible benefits of KDIs in ADPKD as part of a translational project pipeline.

Methods

Patients with ADPKD who had already used KDIs were recruited to retrospectively collect observational and medical data about beneficial or adverse effects and the feasibility and safety of KDIs in questionnaire-based interviews.

Results

A total of 131 ADPKD patients took part in this study. About 74 executed a KD and 52 a TRD for 6 months on average. A total of 86% of participants reported that KDIs had improved their overall health, 67% described improvements in ADPKD-associated health issues, 90% observed significant weight loss, 64% of participants with hypertension reported improvements in blood pressure, 66% noticed adverse effects that are frequently observed with KDIs, 22 participants reported safety concerns like hyperlipidemia, 45 participants reported slight improvements in estimated glomerular filtration rate and 92% experienced KDIs as feasible while 53% reported breaks during their diet.

Conclusions

Our preliminary data indicate that KDIs may be safe, feasible and potentially beneficial for ADPKD patients, highlighting that prospective clinical trials are warranted to confirm these results in a controlled setting and elucidate the impact of KDIs specifically on kidney function and cyst progression.

FGF21 prevents low-protein diet-induced renal inflammation in aged mice

Low-protein (LP) diets extend lifespan through a comprehensive improvement in metabolic health across multiple tissues and organs. Many of these metabolic responses to protein restriction are secondary to transcriptional activation and release of FGF21 from the liver. However, the effects of an LP diet on the kidney in the context of aging has not been examined. Therefore, the goal of the current study was to investigate the impact of chronic consumption of an LP diet on the kidney in aging mice lacking FGF21. Wild-type (WT; C57BL/6J) and FGF21 knockout (KO) mice were fed a normal protein diet (20% casein) or an LP (5% casein) diet ad libitum from 3 to 22 mo of age. The LP diet led to a decrease in kidney weight and urinary albumin-to-creatinine ratio in both WT and FGF21 KO mice. Although the LP diet produced only mild fibrosis and infiltration of leukocytes in WT kidneys, the effects were significantly exacerbated by the absence of FGF21. Accordingly, transcriptomic analysis showed that inflammation-related pathways were significantly enriched and upregulated in response to LP diet in FGF21 KO mice but not WT mice. Collectively, these data demonstrate that the LP diet negatively affected the kidney during aging, but in the absence of FGF21, the LP diet-induced renal damage and inflammation were significantly worse, indicating a protective role of FGF21 in the kidney.NEW & NOTEWORTHY Long-term protein restriction is not advantageous for an otherwise healthy, aging kidney, as it facilitates the development of renal tubular injury and inflammatory cell infiltration. We provide evidence using FGF21 knockout animals that FGF21 is essential to counteract the renal injury and inflammation during aging on a low-protein diet.

New approaches in the nutritional treatment of advanced chronic kidney disease

INTRODUCTION

Patients with advanced chronic kidney disease (ACKD) have a high prevalence of malnutrition. The dietary restrictions that we usually apply in terms of macro and micronutrients force our patients to follow dietary guidelines that deviate from healthy patterns.

OBJECTIVES

To determine if a personalized nutritional intervention program, minimizing the usual restrictions would be justified in case it improved the evolution of kidney disease compared to standard treatment.

SECONDARY OBJECTIVES

To determine changes in nutrient intakes and in anthropometric and biochemical parameters, as well as quantify episodes of hyperkalemia.

MATERIAL AND METHODS

A single-center, randomized and controlled educational intervention clinical trial was conduct in patients from the ERCA outpatients clinic at the Complejo Hospitalario Universitario de Albacete. 75 patients were included, assigning 35 to a Control group and 40 to the Intervention group with 1-year follow-up. The nutritional status was determined using anthropometric data, body composition by Bioimpedance, blood and urine biochemical parameters and a 24-h recall questionnaire. The nutritional intervention was carried out in three different ways: individual, collective and telephone recall.

RESULTS

At the beginning of the study, the BMI showed a situation of weight excess with a mean of 28.83 kg/m2 (5.4) in men and 26.96 kg/m2 (4.09) in women. 70% of our patients had overweight. The abdominal circumference was 105.3 cm (10.2) and 92.3 cm (13.7) for men and women respectively without significant changes throughout the study. The percentage of fat mass (FM) was high in both groups for men and women throughout the study. We did not find biochemical parameters of malnutrition and only significant differences were observed in glomerular filtration rate (GFR), which increased in the intervention group. No patient presented any episodes of hyperkalemia during the study. The energy intake in both groups showed an inadequate distribution of macronutrients with a poor intake of carbohydrates (CH) that was supplemented with an excess of fat. In the case of micronutrients, we did observe an increase in potassium and fiber intakes with a decrease in sodium and phosphorus in the intervention group.

CONCLUSIONS

Malnutrition is not exclusively an intake deficit and encompasses both the problems derived from a deficit and an excess of nutrients intake. Un to 70% of our patients showed weight excess and a fat mass higher than desirable. The implementation of an individualized nutritional education program, including a vegetables and fiber rich diet, less atherogenic, not only did not cause electrolyte alterations but also slowed the progression of kidney disease.

Childhood risk factors for adulthood chronic kidney disease

Chronic kidney disease (CKD) is a major public health challenge, affecting as much as 8 to 18% of the world population. Identifying childhood risk factors for future CKD may help clinicians make early diagnoses and initiation of preventive interventions for CKD and its attendant comorbidities as well as monitoring for complications. The purpose of this review is to describe childhood risk factors that may predict development of overt kidney disease later in life. Currently, there are multiple childhood risk factors associated with future onset and progression of CKD. These risk factors can be grouped into five categories: genetic factors (e.g., monogenic or risk alleles), perinatal factors (e.g., low birth weight and prematurity), childhood kidney diseases (e.g., congenital anomalies, glomerular diseases, and renal cystic ciliopathies), childhood onset of chronic conditions (e.g., cancer, diabetes, hypertension, dyslipidemia, and obesity), and different lifestyle factors (e.g., physical activity, diet, and factors related to socioeconomic status). The available published information suggests that the lifelong risk for CKD can be attributed to multiple factors that appear already during childhood. However, results are conflicting on the effects of childhood physical activity, diet, and dyslipidemia on future renal function. On the other hand, there is consistent evidence to support follow-up of high-risk groups.

Management of Obesity in Adults with CKD

Obesity is a leading public health problem that currently affects over 650 million individuals worldwide. Although interest in the adverse effects of obesity has grown exponentially in recent years, less attention has been given to studying its management in individuals with CKD. This relatively unexplored area should be considered a high priority because of the rapid growth and high prevalence of obesity in the CKD population, its broad impact on health and outcomes, and its modifiable nature. This article begins to lay the groundwork in this field by providing a comprehensive overview that critically evaluates the available evidence related to obesity and kidney disease, identifies important gaps in our knowledge base, and integrates recent insights in the pathophysiology of obesity to help provide a way forward in establishing guidelines as a basis for managing obesity in CKD. Finally, the article includes a kidney-centric algorithm for management of obesity that can be used in clinical practice.

The Effect of Bariatric Surgery versus Intensive Medical Care on Prevention of Microalbuminuria in Patients with Type 2 Diabetes: 3 Year Experience of a Prospective Study

BACKGROUND: Bariatric surgery could improve diabetic kidney disease; however, the effect of surgery versus medical therapy on renal out comes needs further evaluation. AIM: The aim of the study was to investigate the effect of sleeve-gastrectomy versus intensive medical therapy on the prevention of albuminuria in patients with Type 2 diabetes mellitus (T2DM). METHODS: This is a prospective study of 33 patients with T2DM undergoing sleeve gastrectomy matched for age, sex, and duration of diabetes to 64 medically treated patients. Urinary albumin/creatinine ratio (uACR) was assessed before and 3–year after intervention. RESULTS: At baseline, there was no significant difference between surgical and medical group regarding body mass index (BMI), blood pressure, Hemoglobin A1c (HbA1c), or uACR. After 3 years of interventions the mean BMI (kg/m2) and HbA1c (%) became significantly lower in the surgical group compared to medical group. Although mean uACR (g/mg) increased after interventions compared to its levels before interventions in both surgical (11.7 ± 4.8 vs.18.2 ± 5.9) g/mg and medical (13.4 ± 4.5 vs.17.1 ± 6) g/mg groups, albuminuria developed in only three surgical patients and two medical patients (p > 0.05). CONCLUSION: Although bariatric surgery is associated with more reduction in body weight and better glycemic control than intensive medical therapy, sleeve-gastrectomy may not be superior to intensive medical care in prevention of microalbuminuria in patients with T2DM.

Interventions for weight loss in people with chronic kidney disease who are overweight or obese

BACKGROUND

Obesity and chronic kidney disease (CKD) are highly prevalent worldwide and result in substantial health care costs. Obesity is a predictor of incident CKD and progression to kidney failure. Whether weight loss interventions are safe and effective to impact on disease progression and clinical outcomes, such as death remains unclear.

OBJECTIVES

This review aimed to evaluate the safety and efficacy of intentional weight loss interventions in overweight and obese adults with CKD; including those with end-stage kidney disease (ESKD) being treated with dialysis, kidney transplantation, or supportive care.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 14 December 2020 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs of more than four weeks duration, reporting on intentional weight loss interventions, in individuals with any stage of CKD, designed to promote weight loss as one of their primary stated goals, in any health care setting.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study eligibility and extracted data. We applied the Cochrane 'Risk of Bias' tool and used the GRADE process to assess the certainty of evidence. We estimated treatment effects using random-effects meta-analysis. Results were expressed as risk ratios (RR) for dichotomous outcomes together with 95% confidence intervals (CI) or mean differences (MD) or standardised mean difference (SMD) for continuous outcomes or in descriptive format when meta-analysis was not possible.

MAIN RESULTS

We included 17 RCTs enrolling 988 overweight or obese adults with CKD. The weight loss interventions and comparators across studies varied. We categorised comparisons into three groups: any weight loss intervention versus usual care or control; any weight loss intervention versus dietary intervention; and surgical intervention versus non-surgical intervention. Methodological quality was varied, with many studies providing insufficient information to accurately judge the risk of bias. Death (any cause), cardiovascular events, successful kidney transplantation, nutritional status, cost effectiveness and economic analysis were not measured in any of the included studies. Across all 17 studies many clinical parameters, patient-centred outcomes, and adverse events were not measured limiting comparisons for these outcomes. In studies comparing any weight loss intervention to usual care or control, weight loss interventions may lead to weight loss or reduction in body weight post intervention (6 studies, 180 participants: MD -3.69 kg, 95% CI -5.82 to -1.57; follow-up: 5 weeks to 12 months, very low-certainty evidence). In very low certainty evidence any weight loss intervention had uncertain effects on body mass index (BMI) (4 studies, 100 participants: MD -2.18 kg/m², 95% CI -4.90 to 0.54), waist circumference (2 studies, 53 participants: MD 0.68 cm, 95% CI -7.6 to 6.24), proteinuria (4 studies, 84 participants: 0.29 g/day, 95% CI -0.76 to 0.18), systolic (4 studies, 139 participants: -3.45 mmHg, 95% CI -9.99 to 3.09) and diastolic blood pressure (4 studies, 139 participants: -2.02 mmHg, 95% CI -3.79 to 0.24). Any weight loss intervention made little or no difference to total cholesterol, high density lipoprotein cholesterol, and inflammation, but may lower low density lipoprotein cholesterol. There was little or no difference between any weight loss interventions (lifestyle or pharmacological) compared to dietary-only weight loss interventions for weight loss, BMI, waist circumference, proteinuria, and systolic blood pressure, however diastolic blood pressure was probably reduced. Furthermore, studies comparing the efficacy of different types of dietary interventions failed to find a specific dietary intervention to be superior for weight loss or a reduction in BMI. Surgical interventions probably reduced body weight (1 study, 11 participants: MD -29.50 kg, 95% CI -36.4 to -23.35), BMI (2 studies, 17 participants: MD -10.43 kg/m², 95% CI -13.58 to -7.29), and waist circumference (MD -30.00 cm, 95% CI -39.93 to -20.07) when compared to non-surgical weight loss interventions after 12 months of follow-up. Proteinuria and blood pressure were not reported. All results across all comparators should be interpreted with caution due to the small number of studies, very low quality of evidence and heterogeneity across interventions and comparators.

AUTHORS' CONCLUSIONS

All types of weight loss interventions had uncertain effects on death and cardiovascular events among overweight and obese adults with CKD as no studies reported these outcome measures. Non-surgical weight loss interventions (predominately lifestyle) appear to be an effective treatment to reduce body weight, and LDL cholesterol. Surgical interventions probably reduce body weight, waist circumference, and fat mass. The current evidence is limited by the small number of included studies, as well as the significant heterogeneity and a high risk of bias in most studies.

Strategies to Treat Obesity in Patients With CKD

Obesity prevalence continues to increase worldwide, accompanied by a rising tide of hypertension, diabetes, and chronic kidney disease (CKD). Although body mass index is typically used to assess obesity in clinical practice, altered body composition (eg, reduced muscle mass and increased visceral adiposity) are common among patients with CKD. Weight loss achieved through behavioral modification or medications reduces albuminuria and in some cases slows the decline in estimated glomerular filtration rate. Use of medications that promote weight loss with favorable cardiovascular risk profiles should be promoted, particularly in patients with type 2 diabetes, obesity, and CKD. For those who fail to achieve weight loss through lifestyle modification, bariatric surgery should be considered because observational studies have shown reductions in risk for estimated glomerular filtration rate decline and kidney failure. Uncertainty persists on the risk to benefit ratio of intentional weight loss in patients with kidney failure due to the lack of prospective trials and limitations of observational data. Regardless, sleeve gastrectomy is increasingly being used for patients with kidney failure and severe obesity, with success in achieving sustained weight loss, improved access to kidney transplantation, and favorable posttransplantation outcomes. More research is needed assessing long-term cardiovascular and kidney outcomes of most weight loss medications.

Effect of an Intensive Weight-Loss Lifestyle Intervention on Kidney Function: A Randomized Controlled Trial

INTRODUCTION

Large randomized trials testing the effect of a multifactorial weight-loss lifestyle intervention including Mediterranean diet (MedDiet) on renal function are lacking. Here, we evaluated the 1-year efficacy of an intensive weight-loss intervention with an energy-reduced MedDiet (erMedDiet) plus increased physical activity (PA) on renal function.

METHODS

Randomized controlled "PREvención con DIeta MEDiterránea-Plus" (PREDIMED-Plus) trial is conducted in 23 Spanish centers comprising 208 primary care clinics. Overweight/obese (n = 6,719) adults aged 55-75 years with metabolic syndrome were randomly assigned (1:1) to an intensive weight-loss lifestyle intervention with an erMedDiet, PA promotion, and behavioral support (intervention) or usual-care advice to adhere to an energy-unrestricted MedDiet (control) between September 2013 and December 2016. The primary outcome was 1-year change in estimated glomerular filtration rate (eGFR). Secondary outcomes were changes in urine albumin-to-creatinine ratio (UACR), incidence of moderately/severely impaired eGFR (<60 mL/min/1.73 m2) and micro- to macroalbuminuria (UACR ≥30 mg/g), and reversion of moderately (45 to <60 mL/min/1.73 m2) to mildly impaired GFR (60 to <90 mL/min/1.73 m2) or micro- to macroalbuminuria.

RESULTS

After 1 year, eGFR declined by 0.66 and 1.25 mL/min/1.73 m2 in the intervention and control groups, respectively (mean difference, 0.58 mL/min/1.73 m2; 95% CI: 0.15-1.02). There were no between-group differences in mean UACR or micro- to macroalbuminuria changes. Moderately/severely impaired eGFR incidence and reversion of moderately to mildly impaired GFR were 40% lower (HR 0.60; 0.44-0.82) and 92% higher (HR 1.92; 1.35-2.73), respectively, in the intervention group.

CONCLUSIONS

The PREDIMED-Plus lifestyle intervention approach may preserve renal function and delay CKD progression in overweight/obese adults.

Aspects regarding renal morphophysiology of fruit-eating and vampire bats

Bats have adapted to many different feeding habits, which are known to induce morphophysiological adaptations in several tissues, especially those particularly involved with absorption, metabolism and excretion. The common vampire bat (Desmodus rotundus) has a very unique diet (blood), which, among other challenges, seems to pose a risk to their kidneys, due to the increased nitrogen excretion imposed by their remarkably high protein meal. Fruit-eating bats (Artibeus lituratus) consume a high carbohydrate diet and may be taken as a suitable species for this dietary comparative study. Here we aimed at investigating the renal morphology and stereology, kidneys antioxidant capacity, and plasma antidiuretic hormone (ADH) concentrations in adult fruit-eating and vampire bats. Sixteen animals were captured and used in this study, being 8 adult males from each species. Our results showed higher morphological standards of glomerular area, volumetric density of glomeruli, and renal somatic index for vampire bats, as well as higher reactive species of oxygen (ROS) production, such as nitric oxide (NO), higher plasma iron reduction ability (FRAP), higher activity of the antioxidant enzyme glutathione-S-transferase (GST) and a higher malondialdehyde production (MDA) in vampires' kidneys, compared to the fruit-eating species. The activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) were higher in fruit-eating bats. Plasma ADH concentrations were not different between species. Taken together, the renal morphophysiology conditions presented by vampire bats might be associated with a high demand for nitrogenous products excretion imposed by protein and iron overload. These features may play an important role on preventing protein-overload nephropathy, allowing vampires to survive under such a unique diet.

Nutritional management in patients with chronic kidney disease

The global prevalence of chronic kidney disease (CKD) is increasing with the aging of populations worldwide. As kidney function declines, the accumulation of metabolic waste products and excessive electrolytes can significantly impair the health of patients with CKD. As nutritional management of patients with CKD is thought to control uremic symptoms and provide beneficial effects on the progression of kidney dysfunction, the diet of patients with CKD should be an important consideration in their care. Many guidelines recommend limiting protein intake in these patients, as high-protein diets aggravate kidney dysfunction. Excess sodium may be associated with CKD progression and all-cause mortality and, therefore, limiting salt intake is generally recommended. Low potassium is associated with muscle weakness and hypertension, whereas high potassium is associated with cardiac arrhythmia. Therefore, recent guidelines recommend adjusting dietary potassium intake on an individual basis to maintain serum potassium levels within the normal range. Appropriate dietary calcium intake is recommended to maintain calcium balance in patients with CKD G3, G4. Given the many dietary considerations for patients with CKD, effective nutritional management is challenging. Individualized strategies are needed to ensure the best outcome for patients with CKD.

Inflammatory mediators in the adipo-renal axis: leptin, adiponectin, and soluble ICAM-1

A lower 24-h urine pH (24h-pH), i.e., a higher renal excretion of free protons, at a given acid load to the body, denotes a reduction in the kidney's capacity for net acid excretion (NAE). There is increasing evidence, not only for patients with type 2 diabetes but also for healthy individuals, that higher body fatness or waist circumference (WC) has a negative impact on renal function to excrete acids (NAE). We hypothesized that adiposity-related inflammation molecules might mediate this relation between adiposity and renal acid excretion function. Twelve biomarkers of inflammation were measured in fasting blood samples from 162 adult participants (18-25 yr old) of the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) study who had undergone anthropometric measurements and collected 24-h urine samples. Both Baron and Kenny's (B&K's) steps to test mediation and causal mediation analysis were conducted to examine the potential mediatory roles of biomarkers of inflammation in the WC-24-h pH relationship after strictly controlling for laboratory-measured NAE. In B&K's mediation analysis, leptin, soluble intercellular adhesion molecule 1 (sICAM-1), and adiponectin significantly associated with the outcome 24-h pH and attenuated the WC-pH relation. In agreement herewith, causal mediation analysis estimated the "natural indirect effects" of WC on 24-h pH via leptin (P = 0.01) and adiponectin (P = 0.03) to be significant, with a trend for sICAM-1 (P = 0.09). The calculated proportions mediated by leptin, adiponectin, and sICAM-1 were 64%, 23%, and 12%, respectively. Both mediation analyses identified an inflammatory cytokine (leptin) and an anti-inflammatory cytokine (adiponectin) along with sICAM-1 as being potentially involved in mediating adiposity-related influences on renal acid excretion capacity.

The Effects of High-Protein Diets on Kidney Health and Longevity

Although high-protein diets continue to be popular for weight loss and type 2 diabetes, evidence suggests that worsening renal function may occur in individuals with-and perhaps without-impaired kidney function. High dietary protein intake can cause intraglomerular hypertension, which may result in kidney hyperfiltration, glomerular injury, and proteinuria. It is possible that long-term high protein intake may lead to de novo CKD. The quality of dietary protein may also play a role in kidney health. Compared with protein from plant sources, animal protein has been associated with an increased risk of ESKD in several observational studies, including the Singapore Chinese Health Study. Potential mediators of kidney damage from animal protein include dietary acid load, phosphate content, gut microbiome dysbiosis, and resultant inflammation. In light of such findings, adopting current dietary approaches that include a high proportion of protein for weight reduction or glycemic control should be considered with care in those at high risk for kidney disease. Given the possibility of residual confounding within some observational studies and the conflicting evidence from previous trials, long-term studies including those with large sample sizes are warranted to better ascertain the effects of high protein intake on kidney health.

The Effects of Different Quantities and Qualities of Protein Intake in People with Diabetes Mellitus

The recommended amount and quality of protein in diets of diabetic patients are highly controversial. In order to provide evidence-based information, the Diabetes Nutrition Study Group (DNSG) used a grading procedure used for quality of evidence and strength of recommendations (GRADE). A protein intake of 10% to 20% of energy intake (E%) or about 0.8 to 1.3 g/kg body weight in people below 65 years of age, and 15% to 20% of E% in people above 65 years of age appeared safe in weight-stable conditions. There were no intervention studies addressing metabolic effects, mortality, or cardiovascular events over prolonged periods. Body weight is closely linked to metabolic control and high protein diets are often recommended. Weight-loss diets that include 23% to 32% of E% as protein for up to one year reduced blood pressure and body weight slightly but significantly more than lower protein diets, whereas blood lipids, fasting blood glucose, and HbA1c improved similarly with higher or lower protein intakes in participants with a glomerular filtration rate (GFR) >60 mL/min/1.73 m2. Patients with a GFR <60 mL/min/1.73 m2 did not show a faster decline of GFR or kidney function with protein intakes around 0.8 g/kg body weight as compared with lower intakes, thereby arguing against a restriction. The effects of protein intake on diabetic eye or nerve disease have not been reported. There are a number of studies that have compared different types of animal proteins (milk, chicken, beef, pork, and fish) or compared animal with plant protein in diabetic patients and have reported a greater reduction of serum cholesterol with plant protein. In summary, the suggested range of protein intake appears to be safe and can be adapted according to personal dietary preferences.

High-Protein Diet-Induced Glomerular Hyperfiltration Is Dependent on Neuronal Nitric Oxide Synthase β in the Macula Densa via Tubuloglomerular Feedback Response

It is well known that high protein intake increases glomerular filtration rate. Evidence from several studies indicated that NO and tubuloglomerular feedback (TGF) mediate the effect. However, a recent study with a neuronal NO synthase-α knockout model refuted this mechanism and concluded that neither neuronal NO synthase nor TGF response is involved in the protein-induced hyperfiltration. To examine the discrepancy, this study tested a hypothesis that neuronal NO synthase-β in the macula densa mediates the high-protein diet-induced glomerular hyperfiltration via TGF mechanism. We examined the effects of high protein intake on NO generation at the macula densa, TGF response, and glomerular filtration rate in wild-type and macula densa-specific neuronal NO synthase KO mice. In wild-type mice, high-protein diet increased kidney weight, glomerular filtration rate, and renal blood flow, while reduced renal vascular resistance. TGF response in vivo and in vitro was blunted, and NO generation in the macula densa was increased following high-protein diet, associated with upregulations of neuronal NO synthase-β expression and phosphorylation at Ser1417. In contrast, these high-protein diet-induced changes in NO generation at the macula densa, TGF response, renal blood flow, and glomerular filtration rate in wild-type mice were largely attenuated in macula densa-specific neuronal NO synthase KO mice. In conclusion, we demonstrated that high-protein diet-induced glomerular hyperfiltration is dependent on neuronal NO synthase β in the macula densa via TGF response.

Effect of weight loss on the estimated glomerular filtration rates of obese patients at risk of chronic kidney disease: the RIGOR-TMU study

BACKGROUND

Weight-reduction therapies, including bariatric surgery (BS), are standard treatments for severely obese patients with type 2 diabetes; however, the outcomes of these therapies are inconclusive for obese patients with chronic kidney disease (CKD). This study aimed to investigate the effects of BS or non-surgical interventions on the estimated glomerular filtration rate (eGFR) and to determine whether BS can be recommended for renal function preservation based on body mass index (BMI) and eGFR changes in obese patients with CKD.

METHODS

This study used data from the weight Reduction Intervention on GFR in Obese Patients with Renal Impairment-Taipei Medical University (TMU) study, which was a large, long-term, propensity score-matched cohort study based on clinical data from patients who registered at weight-reduction centres at TMU and its affiliated hospitals from 2008 to 2016. The patients were stratified according to whether they had undergone BS and into the mild, moderate, and high CKD risk groups using the Kidney Disease: Improving Global Outcomes guidelines. The primary outcome was the eGFR calculated using the Taiwan Chronic Kidney Disease-Epidemiology Collaboration equation. Cox regression models were used to determine hazard ratios (HRs) for eGFR decreases ≥25%.

RESULTS

A total of 4332 obese patients were enrolled in this study. After propensity score matching, 1620 patients, including 60.2% women, with a mean age of 36.5 (9.9) years were divided into BS or non-surgery groups (n = 810 per group). The overall mean eGFRs increased by 4.4 (14) mL/min·1.73 m² and decreased by 6.4 (16.0) mL/min·1.73 m² in the BS and non-surgery groups, respectively. The decrease in BMI in the BS and non-surgery groups were 2.5 and 1.3 kg/m² , respectively. In the moderate/high CKD risk BS group, a significant correlation was evident between an increased eGFR and a reduced BMI (Spearman's correlation -0.229, P < 0.001). The Cox regression analysis showed that the BS group had a significantly lower risk of an eGFR decline ≥25% at 12 months [adjusted HR (aHR) 0.47, P = 0.03). After BS, obese patients with hypertension or albuminuria had significantly lower risks of eGFR declines ≥25% (aHR 0.37, P = 0.02 and aHR 0.13, P = 0.0018, respectively).

CONCLUSIONS

Bariatric surgery was associated with eGFR preservation in all obese patients and, particularly, in those with moderate-to-high CKD risks. A longer term outcome study is warranted to determine the benefits of BS for CKD patients.

Utilizing a low-carbohydrate/high-protein diet to improve metabolic health in individuals with spinal cord injury (DISH): study protocol for a randomized controlled trial

Background

Metabolic disorders (e.g., impaired glucose tolerance, insulin resistance, and type 2 diabetes) are more prevalent in people with spinal cord injury (SCI) than able-bodied individuals. Dietary modification is a more cost-effective treatment option than pharmacological therapies for reducing the risk of metabolic dysfunction. Lowering carbohydrate, increasing protein, and maintaining a proper dietary fat intake are expected to induce favorable adaptations in glucose control, body fat distribution, and the composition of the gut microbiome. However, dietary modification has not been rigorously investigated in people with SCI. The purpose of this study is to determine if an 8-week low-carbohydrate/high-protein (LC/HP) dietary intervention will show improvements in clinically important metrics of metabolic function, body composition, the composition of gut bacteria, and quality of life.

Methods/design

We intend to recruit 100 participants with chronic traumatic SCI (3 years postinjury, C5–L2, American Spinal Injury Association impairment scale A–D, and aged 18–65 years) and insulin resistance, impaired glucose tolerance or untreated type 2 diabetes and randomly assign them to an 8-week LC/HP dietary intervention group or a control group. The daily LC/HP dietary intervention includes ~ 30% total energy as protein (1.6 g/kg per day) with a carbohydrate-to-protein ratio < 1.5 and fat intake set at ~ 30% of the total energy intake. The control group does not receive any dietary intervention and are continuing with their regular daily diets. Glucose tolerance, insulin sensitivity, β-cell function, body composition, gut microbiome composition, and quality of life measures are assessed at week 1, before starting the LC/HP dietary intervention, and at week 8, after completion of the LC/HP dietary intervention.

Discussion

New information derived from this project will result in the development of a low-cost, simple, self-administered LC/HP dietary intervention for improving metabolic function in individuals with chronic SCI, improved understanding of the composition of gut bacteria in SCI, and how a LC/HP dietary intervention alters gut bacteria composition. In addition, this project will improve our understanding of the relationship between metabolic function and quality of life in individuals with long-standing SCI.

Trial registration

ClinicalTrials.gov, NCT03207841. Registered on 5 June 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3520-3) contains supplementary material, which is available to authorized users.

A single-arm pilot study of metformin in patients with autosomal dominant polycystic kidney disease

Background

Metformin has shown promising results regarding cystogenesis inhibition in preclinical studies with autosomal dominant polycystic kidney disease (ADPKD) models. We designed a prospective, preliminary, single-arm study to evaluate the tolerability, safety and the effect of Metformin on kidney function and body mass index (BMI) in Romanian patients with ADPKD.

Methods

We enrolled 34 adult patients with ADPKD, chronic kidney disease (CKD) stages 1–5 not on dialysis and without diabetes mellitus. The primary endpoint was to assess the tolerability and safety of Metformin. The secondary endpoints evaluated changes in estimated glomerular filtration rate (eGFR), body mass index (BMI) and renal replacement therapy (RRT) necessity. Patients received an initial dose of Metformin of 500 mg/day within the first month that was increased to 1000 mg/day thereafter according to tolerability. Change in eGFR and BMI was expressed as mean difference with the corresponding 95% confidence intervals and as a percentage. For the primary endpoint, we included all 34 enrolled patients. To assess the secondary endpoint, intention-to-treat (ITT) and per-protocol (PP) analysis was performed.

Results

Sixteen patients out of 34 completed the follow-up period at 24 months. Eighteen patients developed adverse events and 63.6% of these events were gastrointestinal related. Nausea was the most common adverse event (17.6%). Two patients (5.8%) permanently discontinued medication due to adverse events. We recorded no case of hypoglycemia, lactic acidosis or death. Mean eGFR changed by − 1.57 ml/min/1.73m² (95%CI:-22.28 to 19.14, P = 0.87) in ITT and by − 4.57 ml/min/1.73m² (95%CI:-28.03 to 18.89, P = 0.69) in PP population. Mean BMI change was − 1.10 kg/m² (95%CI:-3.22 to 1.02, P = 0.30) in ITT population and − 0.80 kg/m² (95%CI:-3.27 to 1.67, P = 0.51) in PP analysis. Three patients (8.8%) needed RRT.

Conclusions

Metformin was well tolerated, had a good safety profile even in ADPKD patients with advanced CKD and it was not associated with change in eGFR or BMI across the follow-up period.

Trial registration

The study was retrospectively registered on https://www.isrctn.com (number ISRCTN 93749377); date registered: 02/25/2019.