Effect of low-carbohydrate diet on markers of renal function in patients with type 2 diabetes: A meta-analysis

Ketogenic diets in chronic kidney disease patients: a review for skeptics by skeptics

Over the last few decades, there has been growing interest in the use of ketogenic diets, mainly as a weight loss strategy. Obesity and diabetes are major risk factors for kidney disease, and obese patients with chronic kidney disease (CKD) are potential candidates for weight reducing diets, among them ketogenic diets. Of further relevance to nephrology, a limited number of recent studies suggests a favorable effect of ketogenic diets in patients affected by autosomal dominant polycystic kidney disease (ADPKD). However, concerns remain about safety in patients with CKD, particularly in the long term and in those with poor residual kidney function. The confusion surrounding the definition of ketogenic diets adds to these concerns. The aim of this review is to summarize information on the main types of ketogenic diets used in daily practice and to discuss the options for their implementation in CKD patients, limiting ultra-processed or industrial preparations.Although further studies are needed to identify the profile of CKD patients who may benefit from the implementation of ketogenic diets to treat obesity or slow the progression of ADPKD, and to assess short- and long-term safety and adherence, the available data appear promising. This critical review is intended to stimulate further research.

Ketogenic diets and β-hydroxybutyrate in the prevention and treatment of diabetic kidney disease: current progress and future perspectives

Diabetic kidney disease (DKD) is the main cause of end-stage renal disease. Ketogenic diets (KD) is a high-fat, low-carbohydrate diet. KD produces ketone bodies to supplement energy in the case of insufficient glucose in the body. β-Hydroxybutyrate (BHB) is the main component of ketone bodies. BHB serves as "ancillary fuel" substituting (but also inducing) anti-oxidative, anti-inflammatory, and cardio-protective features by binding to several target proteins, including histone acylation modification, or G protein-coupled receptors (GPCRs). KD have been used to treat epilepsy, obesity, type-2 diabetes mellitus, polycystic ovary syndrome, cancers, and other diseases. According to recent research, KD and the induced BHB delay DKD progression by improving the metabolism of glucose and lipids, regulating autophagy, as well as alleviating inflammation, oxidative stress and fibrosis. However, due to some side-effects, the role and mechanism of action of KD and BHB in the prevention and treatment of DKD are controversial. This review focuses on recent progress in the research of KD and BHB in clinical and preclinical studies of DKD, and provides new perspectives for DKD treatment.

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.

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.

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.

The role of high fat diet on serum uric acid level among healthy male first degree relatives of type 2 diabetes mellitus

First-degree relatives (FDR) of type 2 diabetes mellitus have increased risk of developing insulin resistance-related disorders including hyperuricemia. We investigated metabolic profile and serum uric acid (SUA) metabolism in response to high-fat diet among healthy male FDR in comparison to those without family history of diabetes. A total of 30 FDR and 30 non-FDR subjects completed a 5-days-hypercaloric diet with fat added to regular daily intake. Despite similar insulin response, FDR displayed different changes in SUA compared to non-FDR subjects (0.26 ± 0.83 mg/dL vs - 0.21 ± 0.78 mg/dL, p = 0.028). In subgroup analyses stratified by body mass index and waist circumference, significant different SUA changes between FDR and non-FDR subjects were only found in obese (0.48 ± 0.87 mg/dL vs - 0.70 ± 0.71 mg/dL, p = 0.001) and centrally obese (0.59 ± 0.83 mg/dL vs - 0.55 ± 0.82 mg/dL, p = 0.011) subgroups. In multivariate analysis, visceral adiposity seemed mediating the different response in SUA metabolism between FDR and non-FDR subjects induced by short-term obesogenic diet.

The association between a low-carbohydrate diet score and the risk of diabetic nephropathy in women: A case-control study

OBJECTIVES

Because evidence linking carbohydrate consumption to diabetic nephropathy (DN) is scarce, and the association between a low-carbohydrate diet (LCD) and DN has not been investigated, we sought to investigate whether a higher LCD score is associated with DN among women.

METHODS

In a case-control study, 105 women with type 2 diabetes mellitus and DN and 105 controls with type 2 diabetes mellitus and without DN who attended Kowsar Diabetes Clinic in Semnan, Iran, were matched for age and diabetes duration. The data related to anthropometric and biochemical measures were collected and a food frequency questionnaire with 147 items was used to assess dietary intake. Based on the food frequency questionnaire, we calculated an LCD score for each study participant. Multivariate logistic regression was performed to examine the association between an LCD score and the odds of developing DN.

RESULTS

The results of the study demonstrated that the LCD score was not significantly associated with DN in the crude model (odds ratio = 0.39; 95% confidence interval, 0.14-1.07; P = 0.06). However, after adjusting for several confounders, subjects in the top quartile of the LCD score were associated with a 71% lower risk of DN (odds ratio [OR] = 0.29; 95% confidence interval, 0.10-0.86; P = 0.02). A significant trend toward decreased urinary albumin excretion was found with an increase in the LCD score (P = 0.005).

CONCLUSIONS

A diet low in carbohydrates was inversely associated with risk of DN. Further observational studies, and preferably randomized controlled trials, are needed to confirm the present results.

Risks and Benefits of Different Dietary Patterns in CKD

Food has the potential to cause and exacerbate many lifestyle diseases. Or it can be used to prevent and treat illnesses like primary hypertension, the metabolic syndrome, and insulin resistance. In parallel, there is also a growing body of evidence of the role of diet in the treatment of kidney disease and its ensuing complications. Popular diets for this purpose have included low-carbohydrate diets, including the ketogenic diet, and higher carbohydrate diets like Mediterranean diets and other plant-based dietary patterns. Low-carbohydrate diets have not shown harm in patients with kidney disease and may benefit a select few. Mediterranean diets have an established record of cardioprotective benefits but also may be beneficial for the kidney. Intermittent fasting has benefits for metabolic health, but limited research exists on the risk or benefit for patients with kidney disease. Plant-based diets, especially those that are lower in protein, may slow kidney disease progression, mitigate uremia, and delay dialysis initiation. Although each dietary pattern has its unique pros and cons, most healthful dietary patterns favor the inclusion of whole, unprocessed foods, preferably from plant-based sources. In this perspective, we discuss the risks and benefits of major popular diets to help guide health care professionals in treating patients with kidney disease.

Nutritional and dietary interventions to prolong renal allograft survival after kidney transplantation

PURPOSE OF REVIEW

Diet plays an important role in slowing progression of chronic kidney disease in native and transplanted kidneys. There is limited evidence on the association on dietary intake with renal allograft function. Mechanisms of major nutrients and dietary patterns with focusing on a plant-based diet related to kidney transplant health and longevity are reviewed.

RECENT FINDINGS

High dietary protein intake may adversely affect renal allograft. Low protein plant-focused diets such as Dietary Approaches to Stop Hypertension, plant-dominant low-protein diet and Mediterranean diets appear associated with favorable outcomes in slowing renal allograft function decline. The mechanism may be related to a change in renal hemodynamic by decreasing glomerular hyperfiltration from low dietary protein intake and plant-based ingredients. Recent observational studies of association between dietary protein intake and kidney allograft outcomes are conflicting. Although strong evidence is still lacking, a low protein diet of 0.6-0.8 g/kg/day with at least 50% of the protein source from plant-based components in kidney transplant recipients with stable kidney allograft function should be considered as the dietary target.

SUMMARY

Dietary intervention with low-protein plant-focused meals may improve outcomes in kidney transplant recipients, but the evidence remains limited and further studies are warranted.

Retrospective cohort study of changes in estimated glomerular filtration rate for patients prescribed a low carb diet

PURPOSE OF REVIEW

Obesity and diabetes contribute to chronic kidney disease (CKD) and accelerate the loss of kidney function. Low carbohydrate diets (LCDs) are associated with weight loss and improved diabetes control. Compared to the typical Western diet, LCDs contain more protein, so individuals with CKD are not included in studies of LCDs. Therefore, there are no studies of LCDs for weight loss and their effects on kidney function.

RECENT FINDINGS

Obesity, hyperglycemia, and hyperinsulinemia can be detrimental to kidney function. LCDs may improve kidney function in patients with obesity and diabetes because they are associated with weight loss, improve blood sugar control, and decrease endogenous insulin production and exogenous insulin requirements.

SUMMARY

In this study, for patients with mildly reduced and moderately to severely reduced kidney function who were prescribed an LCD, their estimated glomerular filtration rate (eGFR) was either unchanged or improved. For those with normal or elevated eGFR, their kidney function was slightly decreased. For those without diabetes, greater weight loss was associated with improved eGFR. Future studies should prospectively measure low carbohydrate dietary adherence and physical activity and directly measure changes in GFR and albuminuria for participants with CKD before and during that diet.

Current Evidence Regarding Low-carb Diets for The Metabolic Control of Type-2 Diabetes

The management of diabetes requires a medical nutrition therapy as an essential part of this treatment. There should be no "one-size-fits-all" eating pattern for different patient´s profiles with diabetes. It is clinically complex to suggest an ideal percentage of calories from carbohydrates, protein and lipids recommended for all patients with diabetes. Among the eating patterns that have shown beneficial effects on metabolic control of patients with type 2 diabetes is the lowcarb diet, since the carbohydrate ingestion is viewed as the most important determinant of postprandial glucose and insulin response. In this context, theoretically, it could make sense to reduce the daily amount of carbohydrates ingested, to achieve lower levels of HbA1c. There could be risks associated to this approach. The adherence to a low-carb diet is here also discussed. This narrative review shows on the current evidence for answering these questions regarding low-carb diet as a possible alternative eating pattern for type 2 diabetes.

Reversal of diabetic tractional retinal detachment attributed to keto diet

A 40-year-old woman, known type 2 diabetes mellitus, obese (100 kg), on insulin (80 units), was under treatment for unstable proliferative diabetic retinopathy with extramacular tractional retinal detachment (TRD) in the left eye. At 1-year follow-up, she developed progression of TRD involving the macula in the left eye for which she was advised surgery. She did not follow-up for 6 months during which time she had adopted a coconut oil-rich ketogenic diet. She reported losing 25 kg body weight along with reversal of diabetes (Glycosylated Haemglobin (HbA1C) of 5.3% without insulin) in the interim. During this 2-year follow-up visit, it was found that there was complete resolution of macular detachment due to TRD in the left eye with stable vision. This was attributed to the impactful ketogenic diet.

One size does not fit all: Nutrition strategies for people with diabetes

Several nutrition strategies and eating patterns can help support self-management among persons with diabetes. This article details the effectiveness of popular eating patterns and nutrition strategies, as well as the role of nurses in facilitating informed patient choices and decisions.

An evidence-based approach to developing low-carbohydrate diets for type 2 diabetes management: A systematic review of interventions and methods

AIM

To identify core diet and delivery components of low-carbohydrate (CHO) diets that have demonstrated efficacy for type 2 diabetes (T2D) management.

MATERIALS AND METHODS

MEDLINE, Pre-MEDLINE, EMBASE, CINAHL and the Cochrane Library of Controlled Trials databases were systematically searched from inception until August 18, 2018. Primary intervention studies of low-CHO diets (≤130 g/d or 26% total energy intake [TEI]) were included. Content analysis was performed on the low-CHO diet protocols classified as safe and effective for T2D management.

RESULTS

A total of 41 studies published between 1963 and 2018 were included, of which 40 were classified as safe and effective for inclusion in the primary analysis. Thirteen studies (13/40) were on very-low-CHO diets (<50 g/d), 14/40 included low-CHO diets (≤130 g/d or 26% TEI), and 13/40 were adapted according to participant progress. Thirty-one studies reported a total energy prescription, of which 18/31 encouraged ad libitum intakes. Twenty studies reported a prescribed dietary fat amount, of which 18/20 were unrestricted or high-fat (>35% TEI). Twenty-six studies reported a prescribed dietary protein amount, of which 22 were unrestricted or were high-protein (>25% TEI). The types of dietary CHO, fat and protein recommended were predominantly whole foods. Common delivery methods reported were dietician and/or physician involvement, moderate to high frequency of contact (≥1 session/month) and use of participant self-monitoring.

CONCLUSIONS

Multiple approaches for developing and delivering a low-CHO diet intervention for T2D management are safe and effective. A comprehensive set of core dietary components to consider in the formulation of low-CHO diet protocols were identified for use in clinical practice and to inform evidence-based guidelines for T2D management.

Protein intake is not associated with progression of diabetic kidney disease in patients without macroalbuminuria

BACKGROUND

Diabetic kidney disease is an important problem in individuals with diabetes. The effect of dietary protein intake on the renal function of patients with diabetes is controversial. Here, we sought to clarify the association between dietary protein intake and changes in the urinary albumin excretion (UAE) or estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes.

METHODS

In this retrospective cohort study, we included 144 patients (70 men, mean ± standard deviation of age 64 ± 10 years, and median (interquartile range) of UAE 15.0 (7.0-38.9) mg/gCr) without an eGFR less than 30 mL/min/1.73 m² and/or UAE greater than or equal to 300 mg/gCr. Changes in the UAE or eGFR were defined as (logarithms [UAE+1] or eGFR at follow-up minus logarithms [UAE+1] or eGFR at baseline examination)/follow-up duration (years). Habitual protein intake was estimated by a self-administered diet history questionnaire.

RESULTS

The median follow-up duration was 5 years. Protein intake (g/kg ideal body weight/day) was not associated with the change in the UAE (r = -0.130, p = 0.120) or change in the eGFR (r = -0.074, p = 0.381). Multiple linear regression analyses showed that after adjusting for covariates, the patients' protein intake was not associated with change in their UAE (standardized regression coefficient: 0.044, p = 0.732) or change in their eGFR (standardized regression coefficient: 0.250, p = 0.085).

CONCLUSIONS

Dietary protein intake does not influence changes in the UAE or eGFR among patients with type 2 diabetes without macroalbuminuria.

Are low-carbohydrate diets safe in diabetic and nondiabetic chronic kidney disease?

Diabetes mellitus and obesity both contribute to chronic kidney disease (CKD) and diabetic kidney disease (DKD), and they can accelerate the loss of kidney function. Dietary intake can potentially have wide-reaching effects on the risk of CKD/DKD and their progression by reducing weight and blood pressure, improving glycemic control, reducing hyperfiltration, and modulating inflammation. Low-carbohydrate (LC) diets can reduce weight and improve glycemic control, but the relatively higher protein content also raises concern in CKD/DKD. Empiric evidence supporting the kidney-related benefits or risks of LC diets is needed to understand the balance of these potential harms and benefits for patients with DKD and is the subject of our review.