Adherence to ketoacids/essential amino acids-supplemented low protein diets and new indications for patients with chronic kidney disease

Low-Protein Diets and Its Synergistic Role in the SGLT2 Inhibitor Era

Low-protein diets (LPDs), usually defined as a daily dietary protein intake of 0.6 to 0.8 g/kg body weight, have been recommended for decades as a safe and effective lifestyle modification to ameliorate inflammatory damage and proteinuria, reduce glomerular hyperfiltration, and improve metabolic acidosis control in patients with chronic kidney disease (CKD). The mechanism for this is largely attributed to altered tubuloglomerular feedback and afferent arteriole contraction leading to decreased glomerular pressure. Additionally, low protein intake reduces urea generation, which can help delay dialysis initiation in advanced CKD. LPDs have different types including plant-dominant LPDs that can exert additional kidney protective effects as a result of dietary protein quality in addition to quantity. In addition, strong clinical evidence shows that a new class of diabetes mellitus medications, the sodium-glucose cotransporter 2 inhibitors, reduces albuminuria and slows the estimated glomerular filtration rate decline in CKD, even in patients without diabetes mellitus, especially if significant proteinuria is present. Given prior studies investigating the effect of LPDs used in conjunction with angiotensin pathway modulators, we argue that LPDs have a synergistic role in disease management and are expected to display additive effects when combined with sodium-glucose cotransporter 2 inhibitor usage or other pharmacologic agents. Even with medical therapy, it is prudent to implement tailored LPDs for different types of CKD.

Supplemented Very Low Protein Diet (sVLPD) in Patients with Advanced Chronic Renal Failure: Clinical and Economic Benefits

The supplemented very low-protein diet (sVLPD) has proven effective in slowing the progression of stage 5 chronic renal failure and postponing the start of the dialysis treatment. However, sVLPD could expose the patient to the risk of malnutrition. This diet is also difficult to implement due to the required intake of large number of keto-analogue/amino acid tablets. In our Center, the Department of Nephrology and Dialysis of Azienda Sanitaria Territoriale n 1, Pesaro-Urbino, of Italy, respecting the guidelines of normal clinical practice, we prescribed sVLPD (0.3 g/prot/day) supplemented with only essential amino acids without the use of ketoanalogues in stage 5 patients and verified its efficacy, safety and clinical and economic effects. Over the 24 months period of observation the progression of chronic kidney disease (CKD) slowed down (mean eGFR 11.6 ± 3.3 vs. 9.3 ± 2.7 mL/min/1.73 m2, p < 0.001) and the start of the dialysis treatment (adjusted HR = 0.361, CI 0.200-0.650, p = 0.001) was delayed without evidence of malnutrition, in compliant vs. non-compliant patients. This led to a substantial cost reduction for the National Health System. This non-interventional longitudinal observational study is part of standard clinical practice and suggests that VLPD supplemented with essential amino acids could be extensively used to reduce the incidence of dialysis treatments, with a favorable economic impact on the NHS.

Potentials of ketogenic diet against chronic kidney diseases: pharmacological insights and therapeutic prospects

BACKGROUND

Chronic kidney disease (CKD) is a worldwide public health concern. Nutritional interventions become a primary concern in managing various diseases, including CKD. Ketogenic diets (KD) are a popular diet and an increasingly used diet for weight loss.

MAIN BODY

With the increasing cases of CKD, KD has been proposed as a treatment by many scientists. Several studies have shown that KD can slow down the progression rate of renal abnormalities. Also, this diet is regarded as a safe route for managing CKD. CKD is generally associated with increased inflammation, oxidative stress, fibrosis, autophagy dysfunction, and mitochondrial dysfunction, while all of these can be attenuated by KD. The protective effect of KD is mainly mediated through inhibition of ROS, NF-κB, and p62 signaling.

CONCLUSIONS

It is suggested that KD could be considered a new strategy for managing and treating CKD more carefully. This review explores the potential of KD on CKD and the mechanism involved in KD-mediated kidney protection.

Assessing Global Kidney Nutrition Care

BACKGROUND AND OBJECTIVES

Nutrition intervention is an essential component of kidney disease management. This study aimed to understand current global availability and capacity of kidney nutrition care services, interdisciplinary communication, and availability of oral nutrition supplements.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The International Society of Renal Nutrition and Metabolism (ISRNM), working in partnership with the International Society of Nephrology (ISN) Global Kidney Health Atlas Committee, developed this Global Kidney Nutrition Care Atlas. An electronic survey was administered among key kidney care stakeholders through 182 ISN-affiliated countries between July and September 2018.

RESULTS

Overall, 160 of 182 countries (88%) responded, of which 155 countries (97%) answered the survey items related to kidney nutrition care. Only 48% of the 155 countries have dietitians/renal dietitians to provide this specialized service. Dietary counseling, provided by a person trained in nutrition, was generally not available in 65% of low-/lower middle-income countries and "never" available in 23% of low-income countries. Forty-one percent of the countries did not provide formal assessment of nutrition status for kidney nutrition care. The availability of oral nutrition supplements varied globally and, mostly, were not freely available in low-/lower middle-income countries for both inpatient and outpatient settings. Dietitians and nephrologists only communicated "sometimes" on kidney nutrition care in ≥60% of countries globally.

CONCLUSIONS

This survey reveals significant gaps in global kidney nutrition care service capacity, availability, cost coverage, and deficiencies in interdisciplinary communication on kidney nutrition care delivery, especially in lower-income countries.

Chronic Kidney Disease: Role of Diet for a Reduction in the Severity of the Disease

Chronic kidney disease affects ~37 million adults in the US, and it is often undiagnosed due to a lack of apparent symptoms in early stages. Chronic kidney disease (CKD) interferes with the body's physiological and biological mechanisms, such as fluid electrolyte and pH balance, blood pressure regulation, excretion of toxins and waste, vitamin D metabolism, and hormonal regulation. Many CKD patients are at risk of hyperkalemia, hyperphosphatemia, chronic metabolic acidosis, bone deterioration, blood pressure abnormalities, and edema. These risks may be minimized, and the disease's progression may be slowed through careful monitoring of protein, phosphorus, potassium, sodium, and calcium, relieving symptoms experienced by CKD patients. In this review, the current Kidney Disease Outcomes Quality Initiative (KDOQI) recommendations are highlighted, reflecting the 2020 update, including explanations for the pathophysiology behind the recommendations. The Dietary Approaches to Stop Hypertension, the Mediterranean diet, and the whole foods plant-based diet are currently being examined for their potential role in delaying CKD progression. Biological explanations for why the whole foods plant-based diet may benefit CKD patients compared to diets that include animal products are examined. Strong evidence continues to support the importance of diet meeting the daily requirement in the prevention and progression of kidney disease, and medical nutrition therapy with a registered dietitian is a critical aspect in medical intervention for CKD.

Metabolic flux analysis of branched-chain amino and keto acids (BCAA, BCKA) and β-hydroxy β-methylbutyric acid across multiple organs in the pig

Branched-chain amino acids (BCAA) and their metabolites the branched-chain keto acids (BCKA) and β-hydroxy β-methylbutyric acid (HMB) are involved in the regulation of key signaling pathways in the anabolic response to a meal. However, their (inter)organ kinetics remain unclear. Therefore, branched-chain amino acids (BCAA) [leucine (Leu), valine (Val), isoleucine (Ile)], BCKA [α-ketoisocaproic acid (KIC), 3-methyl-2-oxovaleric acid (KMV), 2-oxoisovalerate (KIV)], and HMB across organ net fluxes were measured. In multi-catheterized pigs (n = 12, ±25 kg), net fluxes across liver, portal drained viscera (PDV), kidney, and hindquarter (HQ, muscle compartment) were measured before and 4 h after bolus feeding of a complete meal (30% daily intake) in conscious state. Arterial and venous plasma were collected and concentrations were measured by LC- or GC-MS/MS. Data are expressed as mean [95% CI] and significance (P < 0.05) from zero by the Wilcoxon Signed Rank Test. In the postabsorptive state (in nmol/kg body wt/min), the kidney takes up HMB (3.2[1.3,5.0]) . BCKA is taken up by PDV (144[13,216]) but no release by other organs. In the postprandial state, the total net fluxes over 4 h (in µmol/kg body wt/4 h) showed a release of all BCKA by HQ (46.2[34.2,58.2]), KIC by the PDV (12.3[7.0,17.6]), and KIV by the kidney (10.0[2.3,178]). HMB was released by the liver (0.76[0.49,1.0]). All BCKA were taken up by the liver (200[133,268]). Substantial differences are present in (inter)organ metabolism and transport among the BCAA and its metabolites BCKA and HMB. The presented data in a translation animal model are relevant for the future development of optimized clinical nutrition.NEW & NOTEWORTHY Branched-chain amino acids (BCAA) and their metabolites the branched-chain keto acids (BCKA) and β-hydroxy β-methylbutyric acid (HMB) are involved in the regulation of key signaling pathways in the anabolic response to a meal. Substantial differences are present in (inter)organ metabolism and transport among the BCAA and its metabolites BCKA and HMB. The presented data in a translation animal model are relevant for the future development of optimized clinical nutrition.

Ketoanalogue supplements reduce mortality in patients with pre-dialysis advanced diabetic kidney disease: A nationwide population-based study

BACKGROUND & AIMS

Metabolism dysregulation and protein energy wasting occur in patients with chronic kidney disease (CKD) and are associated with poor survival, especially in patients prior to starting dialysis. Accumulating evidence indicates that dietary supplementation with ketoanalogues (KAs, a mixture of branched-chain amino acids) exerts a variety of beneficial effects for patients with CKD. However, the role of KAs in diabetic kidney disease (DKD), one of the major causes of CKD, is still controversial. The aim of this study was to explore the impact of KA supplements on survival in patients with stage 5 DKD who have not yet started dialysis (DKD-5-ND).

METHODS

We analyzed a nationwide cohort retrieved from the National Health Insurance Research Database in Taiwan to study the long-term impact of KA supplements in patients with DKD-5-ND. We enrolled 15,782 incident pre-dialysis DKD patients between January 1, 2004 and December 31, 2007. Landmark analysis was used to eliminate immortal bias, and overlap weighting was used to balance differences between the KA users and nonusers in the beginning. The primary study endpoint was all-cause mortality, and the occurrence of permanent dialysis (presenting the end-stage renal disease, ESRD) and major adverse cardiovascular events (MACEs) was also evaluated. All patients were followed for five years or until death.

RESULTS

The prevalence of KA usage in the DKD-5-ND patients was 6.3%. The 5-year all-cause mortality rate in the KA users was lower than that in the nonusers (34.7% vs 42.7%). After adjusting for known covariates, the KA users still had a lower risk of mortality (adjusted hazard ratio [aHR]: 0.73, 95% confidence interval [CI]: 0.66-0.82). In addition, the incidence of ESRD was also slightly lower among the KA users (90.9% for users vs 91.2% for nonusers, adjusted cause-specific hazard ratio [aCSHR]: 0.65, 95% CI: 0.61-0.69), and the occurrence of MACEs was lower (adjusted incidence rate ratios [aIRR]: 0.76, 95% CI: 0.67-0.86). Although the all-cause mortality was higher among patientsolder than 70 years (60.5% for KA users vs 46.5% for nonusers) the risk reduction seemed prominent among older patients (aHR: 0.65, 95% CI: 0.56-0.76 for patients aged ≥70 years; aHR: 0.82, 95% CI: 0.71-0.96 for patients aged < 70 years). The reduction in risks of mortality was consistent in subgroup analysis and sensitivity tests.

CONCLUSIONS

The use of KA supplements seemed to be beneficial for patients with DKD-5-ND; further in-depth analysis of using KA for these patients is warranted.

Nutritional treatment of advanced CKD: twenty consensus statements

The Italian nephrology has a long tradition and experience in the field of dietetic-nutritional therapy (DNT), which is an important component in the conservative management of the patient suffering from a chronic kidney disease, which precedes and integrates the pharmacological therapies. The objectives of DNT include the maintenance of an optimal nutritional status, the prevention and/or correction of signs, symptoms and complications of chronic renal failure and, possibly, the delay in starting of dialysis. The DNT includes modulation of protein intake, adequacy of caloric intake, control of sodium and potassium intake, and reduction of phosphorus intake. For all dietary-nutritional therapies, and in particular those aimed at the patient with chronic renal failure, the problem of patient adherence to the dietetic-nutritional scheme is a key element for the success and safety of the DNT and it can be favored by an interdisciplinary and multi-professional approach of information, education, dietary prescription and follow-up. This consensus document, which defines twenty essential points of the nutritional approach to patients with advanced chronic renal failure, has been written, discussed and shared by the Italian nephrologists together with representatives of dietitians (ANDID) and patients (ANED).

Effects of Low-Protein, and Supplemented Very Low-Protein Diets, on Muscle Protein Turnover in Patients With CKD

Introduction

Early studies have shown that patients with chronic kidney disease (CKD) are able to maintain nitrogen balance despite significantly lower protein intake, but how and to what extent muscle protein metabolism adapts to a low-protein diet (LPD) or to a supplemented very LPD (sVLPD) is still unexplored.

Methods

We studied muscle protein turnover by the forearm perfusion method associated with the kinetics of ²H-phenylalanine in patients with CKD: (i) in a parallel study in subjects randomized to usual diet (1.1 g protein/kg, n = 5) or LPD (0.55 g protein/kg, n = 6) (Protocol 1); (ii) in a crossover, self-controlled study in subjects on a 0.55 g/kg LPD followed by a sVLPD (0.45 g/kg + amino/ketoacids 0.1 g/kg, n = 6) (Protocol 2).

Results

As compared with a 1.1 g/kg containing diet, a 0.55 g/kg LPD induced the following: (i) a 17% to 40% decrease in muscle protein degradation and net protein balance, respectively, (ii) no change in muscle protein synthesis, (iii) a slight (by approximately 7%, P < 0.06) decrease in whole-body protein degradation, and (iv) an increase in the efficiency of muscle protein turnover. As compared with an LPD, an sVLPD induced the following: (i) no change in muscle protein degradation, and (ii) an approximately 50% decrease in the negative net protein balance, and an increase in the efficiency of muscle protein turnover.

Conclusion

The results of these studies indicate that in patients with CKD the adaptation of muscle protein metabolism to restrained protein intake can be obtained via combined responses of protein degradation and the efficiency of recycling of amino acids deriving from protein breakdown.

Successful pregnancy in a CKD patient on a low-protein, supplemented diet: an opportunity to reflect on CKD and pregnancy in Mexico, an emerging country

Pregnancy is probably the most important challenge in young women with chronic kidney disease (CKD). The challenge is greater in developing countries, in which access to dialysis is uneven, and prenatal care for CKD patients is not uniformly available. This case report summarizes some of the challenges faced by pregnant CKD women in a developing country. A 35-year-old woman, affected by an undiagnosed kidney disease, experienced preeclampsia at 24 years of age, and started dialysis in emergency at age 31 in the context of severe preeclampsia in her second pregnancy. Following slow recovery of kidney function, after 18 months of dialysis she started a moderately restricted, supplemented, low-protein diet, which allowed her to discontinue dialysis. A few months after dialysis discontinuation, she started a new pregnancy in the presence of severely reduced kidney function (serum creatinine 4.6 mg/dl at the last pre-pregnancy control). Interestingly, she discontinued nephrology and nutritional follow-up, mainly because she was worried that she would be discouraged from continuing the pregnancy, but also because she continued to feel well. She self-managed her diet in pregnancy and delivered a healthy baby, with normal intrauterine growth, at term; while the last laboratory data confirmed the presence of severe kidney function impairment, she is still dialysis-free at the time of the present report. Her story, with its happy ending, underlines the importance of dedicated programs for CKD pregnancies in developing countries and confirms the safety of moderately protein-restricted diets in pregnancy.

Non-Traditional Aspects of Renal Diets: Focus on Fiber, Alkali and Vitamin K1 Intake

Renal diets for advanced chronic kidney disease (CKD) are structured to achieve a lower protein, phosphate and sodium intake, while supplying adequate energy. The aim of this nutritional intervention is to prevent or correct signs, symptoms and complications of renal insufficiency, delaying the start of dialysis and preserving nutritional status. This paper focuses on three additional aspects of renal diets that can play an important role in the management of CKD patients: the vitamin K1 and fiber content, and the alkalizing potential. We examined the energy and nutrients composition of four types of renal diets according to their protein content: normal diet (ND, 0.8 g protein/kg body weight (bw)), low protein diet (LPD, 0.6 g protein/kg bw), vegan diet (VD, 0.7 g protein/kg bw), very low protein diet (VLPD, 0.3 g protein/kg bw). Fiber content is much higher in the VD and in the VLPD than in the ND or LPD. Vitamin K1 content seems to follow the same trend, but vitamin K2 content, which could not be investigated, might have a different pattern. The net endogenous acid production (NEAP) value decreases from the ND and LPD to the vegetarian diets, namely VD and VLPD; the same finding occurred for the potential renal acid load (PRAL). In conclusion, renal diets may provide additional benefits, and this is the case of vegetarian diets. Namely, VD and VLPD also provide high amounts of fibers and Vitamin K1, with a very low acid load. These features may have favorable effects on Vitamin K1 status, intestinal microbiota and acid-base balance. Hence, we can speculate as to the potential beneficial effects on vascular calcification and bone disease, on protein metabolism, on colonic environment and circulating levels of microbial-derived uremic toxins. In the case of vegetarian diets, attention must be paid to serum potassium levels.

'Let food be thy medicine…': lessons from low-protein diets from around the world

In this editorial we present the special issue dedicated to low-protein diets (LPDs) in chronic kidney disease, from a global perspective.The experiences gathered from several countries across all continents have created an issue which we hope you will find insightful, and lead to further discussion on this interesting topic.We discover that LPDs are feasible in both developed and low income countries, in patients where literacy is an issue, and are also safe, including during pregnancy and in old age.Patients prescribed a low protein diet are more inclined to follow and adhere to this change in lifestyle, provided the diet has been adapted to meet their own individual needs. With an increasing list of different menu options and better medical advice being offered we no longer need to identify low protein diets with a specific menu, ingredient or supplement, or with a specific level of protein restriction. Evidence shows how the best diet is often the one chosen by the patients, which doesn't drastically affect their day-to-day life, and delays the start of dialysis for as long as is safe under careful clinical control. The colourful menus gathered from all over the world remind us that a low protein diet does not necessarily mean that the pleasure of preparing a delicious meal is lost. The final comment is therefore dedicated to our patients: low protein diets can be beautiful.

Very Low-Protein Diet (VLPD) Reduces Metabolic Acidosis in Subjects with Chronic Kidney Disease: The "Nutritional Light Signal" of the Renal Acid Load

Background: Metabolic acidosis is a common complication of chronic kidney disease; current guidelines recommend treatment with alkali if bicarbonate levels are lower than 22 mMol/L. In fact, recent studies have shown that an early administration of alkali reduces progression of CKD. The aim of the study is to evaluate the effect of fruit and vegetables to reduce the acid load in CKD. Methods: We conducted a case-control study in 146 patients who received sodium bicarbonate. Of these, 54 patients assumed very low-protein diet (VLPD) and 92 were controls (ratio 1:2). We calculated every three months the potential renal acid load (PRAL) and the net endogenous acid production (NEAP), inversely correlated with serum bicarbonate levels and representing the non-volatile acid load derived from nutrition. Un-paired T-test and Chi-square test were used to assess differences between study groups at baseline and study completion. Two-tailed probability values ≤0.05 were considered statistically significant. Results: At baseline, there were no statistical differences between the two groups regarding systolic blood pressure (SBP), diastolic blood pressure (DBP), protein and phosphate intake, urinary sodium, potassium, phosphate and urea nitrogen, NEAP, and PRAL. VLPD patients showed at 6 and 12 months a significant reduction of SBP (p < 0.0001), DBP (p < 0.001), plasma urea (p < 0.0001) protein intake (p < 0.0001), calcemia (p < 0.0001), phosphatemia (p < 0.0001), phosphate intake (p < 0.0001), urinary sodium (p < 0.0001), urinary potassium (p < 0.002), and urinary phosphate (p < 0.0001). NEAP and PRAL were significantly reduced in VLPD during follow-up. Conclusion: VLPD reduces intake of acids; nutritional therapy of CKD, that has always taken into consideration a lower protein, salt, and phosphate intake, should be adopted to correct metabolic acidosis, an important target in the treatment of CKD patients. We provide useful indications regarding acid load of food and drinks—the “acid load dietary traffic light”.

Dietary protein intake and chronic kidney disease

PURPOSE OF REVIEW

High-protein intake may lead to increased intraglomerular pressure and glomerular hyperfiltration. This can cause damage to glomerular structure leading to or aggravating chronic kidney disease (CKD). Hence, a low-protein diet (LPD) of 0.6-0.8 g/kg/day is often recommended for the management of CKD. We reviewed the effect of protein intake on incidence and progression of CKD and the role of LPD in the CKD management.

RECENT FINDINGS

Actual dietary protein consumption in CKD patients remains substantially higher than the recommendations for LPD. Notwithstanding the inconclusive results of the 'Modification of Diet in Renal Disease' (MDRD) study, the largest randomized controlled trial to examine protein restriction in CKD, several prior and subsequent studies and meta-analyses appear to support the role of LPD on retarding progression of CKD and delaying initiation of maintenance dialysis therapy. LPD can also be used to control metabolic derangements in CKD. Supplemented LPD with essential amino acids or their ketoanalogs may be used for incremental transition to dialysis especially on nondialysis days. The LPD management in lieu of dialysis therapy can reduce costs, enhance psychological adaptation, and preserve residual renal function upon transition to dialysis. Adherence and adequate protein and energy intake should be ensured to avoid protein-energy wasting.

SUMMARY

A balanced and individualized dietary approach based on LPD should be elaborated with periodic dietitian counseling and surveillance to optimize management of CKD, to assure adequate protein and energy intake, and to avoid or correct protein-energy wasting.