The low-protein diet for chronic kidney disease: 8 years of clinical experience in a nephrology ward

The Key Role of Nutritional Intervention in Delaying Disease Progression and the Therapeutic Management of Diabetic Kidney Disease-A Challenge for Physicians and Patients

Chronic kidney disease (CKD) represents an increasingly common pathology that affects patients' quality of life, and it is frequently associated with a high mortality rate, especially in the final stages of the disease. At the same time, diabetes mellitus is a chronic disease that contributes to the increased number of patients with CKD through diabetic kidney disease (DKD). The alternation of hypoglycemia with hyperglycemia is a condition in the occurrence of microvascular complications of diabetes, including DKD, which involves structural and functional changes in the kidneys. The therapeutic management of diabetic nephropathy is a much-discussed topic, both from nutritional medical recommendations and a pharmacotherapy perspective. The diet starting point for patients with DKD is represented by a personalized and correct adjustment of macro- and micronutrients. The importance of nutritional status in DKD patients is given by the fact that it represents a modifiable factor, which contributes to the evolution and prognosis of the disease. Since, in most cases, it is necessary to restrict many types of food, malnutrition must be considered and avoided as much as possible.

Low-Protein Diet in Elderly Patients with Chronic Kidney Disease Stage 4 and 5 in Conservative Management: Focus on Sarcopenia Development

INTRODUCTION

Chronic kidney disease is a degenerative and increasingly prevalent condition that includes metabolic abnormalities and is associated with a higher risk of sarcopenia. The conservative approach points primarily to controlling metabolic issues and reducing the risk of malnutrition and sarcopenia, slowing the progression of kidney disease. The present study aims to evaluate the effect of a low-protein diet on malnutrition and sarcopenia.

METHODS

A total of 45 patients (33 male and 12 female) aged over 70 with chronic kidney disease stage 4-5 in conservative management were considered. All patients had a dietary assessment and prescription of personalized low-protein dietary plans (≤0.6 g protein/kg) and a follow-up control between 4 and 6 months. In preliminary and follow-up evaluations, anthropometric data, blood examinations, body composition results, muscle strength, physical performance, and a 3-day food diary were collected.

RESULTS

In the follow-up period, a significant weight loss (p = 0.001) and a decrease in body mass index (p = 0.002) were recorded. Food diaries revealed a significant reduction in protein, sodium, potassium, and phosphorus intake (p < 0.001), with a significant reduction in urea (p < 0.001) and proteinuria (p = 0.01) without any impact on lean mass (p = 0.66). Considerable variations in adherence between food diaries and the prescribed diet were also noted.

CONCLUSIONS

Providing a personalized low-protein diet led to significant benefits in a short period without worsening the patient's nutritional status.

The Role of Protein Restriction in the Progression of Chronic Kidney Disease

Even though nephrology has made much progress, reducing the progression of the chronic kidney disease remains, in fact, one of the biggest challenges. Long before the renal replacement therapy (RRT), it was known that limiting the protein could help almost all uremia symptoms. Although it was proposed as early as the 1960s, it only became widely used in the 1980s. By lowering the urea and other nitrogen wastes and lowering the metabolic acidosis, oxidative stress, and insulin resistance, limiting the amount of protein in your diet can help improve uremic symptoms. Also, limiting the protein in the diet positively controls the cardiovascular complications, including the arterial blood pressure and proteinuria reduction, which are risk factors for CKD progression. This mini-review examines the impact of protein restriction on the possibility of slowing CKD progression in depth.

Personalized Low-Protein Diet Prescription in CKD Population: Merging Evidence From Randomized Trials With Observational Data

Nutritional therapy is a cornerstone of the clinical management of chronic kidney disease (CKD). Nevertheless, randomized controlled trials often have failed to show a relevant benefit of low-protein diets in nonselected CKD populations in terms of slowing the progression of kidney disease and need for dialysis. The more the target population is selected, the less the results can be generalizable to implement in clinical practice. On the contrary, observational studies, especially if performed with patient-centered, flexible approaches, point toward an extensive implementation of dietary protein restriction in different and unselected CKD populations. The observational evidence cannot be disregarded anymore. The most recent guidelines advise implementing low-protein diets or even very-low-protein diets in all CKD patients as early as stage 3. However, the lack of data from large randomized controlled trials on unselected CKD populations as well as on specific subpopulations, such as diabetic or obese patients, which nowadays comprise the majority of CKD subjects, reduces the generalizability of the recommendations. For some patient populations, such as those encompassing very old, nephrotic, or pregnant patients, the literature is even more limited because of the lower prevalence of these conditions and diffused prejudices against reducing protein intake. This pragmatic review discusses the need for integrating information derived from randomized trials with evidence derived from observational studies to guide feasible strategies for more successful implementation of low-protein diets in the treatment of all segments of the CKD population.

Dietary protein and muscle wasting in chronic kidney disease: new insights

PURPOSE OF REVIEW

Muscle wasting is an important health problem in chronic kidney disease (CKD) patients. Protein restriction in the diet can be one of the main causes of muscle wasting in this population. In this review, we aimed to investigate the relationship between dietary protein intake and muscle wasting in CKD patients according to recent literature.

RECENT FINDINGS

The one of the main mechanisms responsible for the muscle wasting is the disturbances in skeletal muscle protein turnover. Muscle wasting primarily occurs when the rates of muscle protein breakdown exceed the muscle protein synthesis. Dietary protein intake represents an important role by causing a potent anabolic stimulus resulting a positive muscle protein balance. Compared to studies made in healthy populations, there are very limited studies in the literature about the relationship between dietary protein intake and muscle wasting in the CKD population. Majority of the studies showed that a more liberal protein intake is beneficial for muscle wasting in especially advanced CKD and hemodialysis population.

SUMMARY

Although evaluating muscle wasting in CKD patients, the amount of protein in the diet of patients should also be reviewed. Although excessive protein intake has some negative consequences on this patient group, a more liberated dietary protein intake should be taken into account in this patient group with muscle wasting and especially in dialysis patients.

Disease-related malnutrition in chronic kidney disease

PURPOSE OF REVIEW

Disease-related malnutrition has complex and multifactorial pathophysiology. It is common in patients with chronic kidney disease (CKD) and has a devastating impact on morbidity and mortality. Given the rising numbers of patients diagnosed with CKD, disease-related malnutrition is an escalating clinical challenge. This review summarises current knowledge in relation to the development, screening and treatments for disease-related malnutrition in CKD.

RECENT FINDINGS

New research has identified other potential causes for the development of malnutrition in CKD, including changes in taste and smell, and effects of polypharmacy. Screening and assessment studies have investigated different tools in relation to the new Global Leadership Initiative on Malnutrition (GLIM) criteria. Different modalities of low protein diets and the potential use of pre and probiotics are being explored. Furthermore, the importance of nutritional support, and possibly exercise during dialysis is being examined in terms of reducing anabolic resistance and catabolism.

SUMMARY

Further research is required to better understand the nuances of the pathophysiology of disease-related malnutrition in CKD. This work should inform not only consistent terminology and the application of assessment tools specific to disease-related malnutrition in CKD but also the development of novel interventions that reflect its multifaceted pathophysiology and impact.

A Narrative Review of Dietary Approaches for Kidney Transplant Patients

A healthy eating pattern has proven to lower the risk of metabolic and cardiovascular diseases. However, there are sparse dietary recommendations for kidney transplant recipients, and the ones available focus only on single nutrients intake, such as sodium, potassium, and proteins, and not on the overall eating pattern. Considering that individuals do not typically consume nutrients in isolation, but as part of a complete dietary pattern, it is challenging for the average transplanted patient to understand and implement specific dietary recommendations. Also, single-nutrient interventions demonstrate largely inconclusive effects, and it seems improbable that they could have a strong enough impact on transplant outcomes. Dietary trends such as plant-based diets, intermittent fasting, low-carb diet/keto-diet, and juicing, have gained major attention from the media. Herein, we review the potential risks and benefits of these diets in kidney transplant recipients and provide an updated dietary recommendation for this population with consideration of current nutritional trends. Overall, the Mediterranean and DASH diets have demonstrated to be the most beneficial dietary patterns to the post kidney transplant population by focusing on less meat and processed foods, while increasing the intake of fresh foods and plant-based choices. We believe that to maintain a healthy lifestyle posttransplant, patients should be educated about the scientific evidence of different diets and choose a dietary pattern that is sustainable long-term.

Effects of ketoanalogues on skeletal muscle mass in patients with advanced chronic kidney disease: real-world evidence

OBJECTIVE

Ketoanalogue (KA) supplementation in patients with chronic kidney disease (CKD) on a restricted protein diet has been shown to maintain their nutritional status in clinical trials. However, a gap existed between the findings of the clinical trials and the real-world practice. The aim of this prospective observational study was to evaluate the KA effect on skeletal muscle mass in patients with stage 4-5 CKD.

METHODS

Among 170 patients with CKD screened, 148 were recruited. Patients were defined as KA or non-KA users. During a 12-mo follow-up, skeletal muscle and body fat mass were measured via bioelectrical impedance analysis at baseline, 6 mo (n = 108), and 12 mo (n = 85).

RESULTS

Among the patients (mean age, 66.5 ± 12.9 y), KA users tended to maintain skeletal muscle and body fat mass, whereas non-KA users had a significantly reduced muscle mass (P = 0.011) and body fat gain (P = 0.004). Stratified by median age, in patients ≥68 y of age, non-KA users yielded the most significant muscle mass reduction and fat mass gain, whereas KA users revealed no changes in skeletal muscle and fat mass.

CONCLUSION

In real-world practice, we concluded that KA supplementation favorably prevents skeletal muscle mass loss and fat mass gain in elderly patients with stage 4-5 CKD.

Quality of Life in CKD Patients on Low-Protein Diets in a Multiple-Choice Diet System. Comparison between a French and an Italian Experience

Prescribing a low-protein diet (LPD) is part of the standard management of patients in advanced stages of chronic kidney disease (CKD). However, studies on the quality of life (QoL) of patients on LPDs are lacking, and the impact these diets have on their QoL is often given as a reason for not prescribing one. We, therefore, decided to assess the QoL in a cohort of CKD stage 3–5 patients followed up by a multiple-choice diet approach in an outpatient nephrology clinic in France. To do so, we used the short version of the World Health Organization’s quality of life questionnaire and compared the results with a historical cohort of Italian patients. We enrolled 153 patients, managed with tailored protein restriction in Le Mans, and compared them with 128 patients on similar diets who had been followed in Turin (Italy). We found there were no significant differences in terms of age (median 73 vs. 74 years, respectively), gender, CKD stage, and comorbidities (Charlson’s Comorbidity Index 7 vs. 6). French patients displayed a greater body mass index (29.0 vs. 25.4, p < 0.001) and prevalence of obesity (41.2 vs. 15.0%, p < 0.001). Baseline protein intake was over the target in France (1.2 g/kg of real body weight/day). In both cohorts, the burden of comorbidities was associated with poorer physical health perception while kidney function was inversely correlated to satisfaction with social life, independently of the type of diet. Our study suggests that the type of LPD they follow does not influence QoL in CKD patients and that a personalized approach towards protein restriction is feasible, even in elderly patients.

Protein intake and renal function in older patients

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is highly prevalent in elderly patients. There is growing recognition of the importance of attention to dietary protein intake (DPI) in this population given their predisposition to age-related changes in kidney function and coexisting comorbidities (i.e., hypertension). We reviewed the impact of DPI on kidney health and survival and the role of dietary protein management in older CKD patients.

RECENT FINDINGS

While kidney function parameters including glomerular filtration rate (GFR) and renal plasma flow are slightly lower in elderly patients irrespective of CKD status, the kidneys' ability to compensate for increased DPI by augmentation of GFR is preserved until 80 years of age or less. However, long-term consumption of high DPI in individuals of older age and/or with CKD may contribute to kidney function deterioration over time. Prescription of a plant-dominant low-protein diet of 0.6-0.8 g/kg/day with more than 50% from plant sources or very low protein diets less than 0.45 g/kg/day supplemented with essential amino acids or their keto-analogues may be effective in preserving kidney function in older patients and their younger counterparts, while also monitoring for development of protein-energy wasting (PEW).

SUMMARY

Using tailored precision nutrition approaches in prescribing plant-dominant low DPI that also maintains adequate energy and nitrogen balance may ameliorate kidney function decline while also preventing development of PEW in elderly patients with CKD.