Optimal nutrition for predialysis chronic kidney disease

Hyperkalemia and Plant-Based Diets in Chronic Kidney Disease

Traditional dietary guidelines for patients with kidney disease recommend restriction of plant foods due to concerns about hyperkalemia and associated adverse events. Studies conducted over several decades have shown that the basis for these guidelines does not match the evidence. Serum potassium levels can be elevated in patients with reduced kidney function after consumption of foods with potassium-based additives or with highly concentrated potassium content such as juices, dried fruit, or purees. However, plant foods may have certain qualities that may blunt potassium retention including their alkalinizing effects, the lack of bioavailable potassium, and the impact of dietary fiber in organic plant foods on colonic potassium excretion. Furthermore, there are many benefits of plant foods that patients with kidney disease may be missing by excluding them from their diets by recommending the historical low-potassium "renal diet." Revised dietary recommendations for kidney health may encourage patient-centered kidney recipes that revolve around plant foods and do not restrict them.

1,3-Butanediol attenuates hypertension and suppresses kidney injury in female rats

Thirty-seven million people in the United States are estimated to have chronic kidney disease (CKD). Hypertension (HTN) is the second leading risk factor for developing kidney disease. A recent study reported that increasing levels of β-hydroxybutyrate levels by administration of its precursor, 1,3-butanediol, decreased salt-induced HTN in male Dahl salt-sensitive (S) rats. The effect of 1,3-butanediol on hypertensive kidney disease in female rats or the absence of high salt has not been investigated. This study tested the hypothesis that 1,3-butanediol attenuates HTN and the progression of CKD in female S-SHR(11) rats. The S-SHR(11) strain is a congenic rat strain generated from genetic modification of the Dahl S rat, previously characterized as a model of accelerated renal disease. Rats received 1,3-butanediol (20% via drinking water) or control for 10 wk and were maintained on a 0.3% NaCl rodent diet (n = 12-14 rats/group). Blood pressure was measured after 6 and 9 wk of treatment by tail-cuff plethysmography; after 10 wk, urine and tissues were collected. Activity of the treatment was confirmed by measuring plasma β-hydroxybutyrate levels, which were greater in the treated group. The 1,3-butanediol-treated group had lower systolic blood pressure, proteinuria, plasma creatinine, and renal fibrosis after 9 wk of treatment compared with controls. The treated group had significantly smaller spleens and increased the renal anti-inflammatory molecules interleukin-10 and granulocyte-macrophage colony-stimulating factor, suggesting reduced inflammation. The present data demonstrate that 1,3-butanediol lowers blood pressure and renal injury in female rats and could be a novel nutritional intervention for the treatment of CKD.

Nutritional Status, Nutrient Intake, and Food Diversity Among Children With Sickle Cell Anemia

Children with sickle cell anemia (SCA) often exhibit nutritional deficiencies and are at high risk of dying before the age of 5 years. Ensuring adequate nutrition is a critical part of health care for such children. This study aimed to investigate the association between nutritional status, nutrient intake, and food diversity in children with SCA. A descriptive cross-sectional study was conducted on 74 children with SCA, between 24 and 71 months of age. Anthropometric measurements, food and nutrients consumption were determined. The prevalence of low weight, stunting, and overweight/obesity were 16.2%, 35.1%, and 16.2%, respectively. Mean folic acid intake was low (49.05%±51.22%), whereas the intakes of protein (426.71%±171.93%), retinol (292.97%±403.88%), phosphorus (204.55%±151.35%), magnesium (233.02%±151.14%), iron (250.76%±165.81%), and zinc (243.21%±148.40%) were high. The dietary phosphorus/protein ratio was high for 31.1% of the children, and 44.6% of the children had low dietary diversity score. No correlation was found between food diversity, nutrient adequacy, and nutritional status. Despite the adequacy of the intake of most micronutrients, diet quality was inadequate, constituting mainly ultraprocessed foods. Knowing the food consumption pattern of these children enables a more resolute nutritional intervention.

Low protein diets in patients with chronic kidney disease: a bridge between mainstream and complementary-alternative medicines?

Dietary therapy represents an important tool in the management of chronic kidney disease (CKD), mainly through a balanced reduction of protein intake aimed at giving the remnant nephrons in damaged kidneys a "functional rest". While dialysis, transplantation, and pharmacological therapies are usually seen as "high tech" medicine, non pharmacological interventions, including diets, are frequently considered lifestyle-complementary treatments. Diet is one of the oldest CKD treatments, and it is usually considered a part of "mainstream" management. In this narrative review we discuss how the lessons of complementary alternative medicines (CAMs) can be useful for the implementation and study of low-protein diets in CKD. While high tech medicine is mainly prescriptive, prescribing a "good" life-style change is usually not enough and comprehensive counselling is required; the empathic educational approach, on which CAMs are mainly, though not exclusively based, may support a successful personalized nutritional intervention.There is no gold-standard, low-protein diet for all CKD patients: from among a relatively vast choice, the best compliance is probably obtained by personalization. This approach interferes with the traditional RCT-based analyses which are grounded upon an assumption of equal preference of treatments (ideally blinded). Whole system approaches and narrative medicine, that are widely used in the study of CAMs, may offer ways to integrate EBM and personalised medicine in the search for innovative solutions respecting individualization, but gaining sound data, such as with partially-randomised patient preference trials.

Ketoanalogue-Supplemented Vegetarian Very Low-Protein Diet and CKD Progression

Dietary protein restriction may improve determinants of CKD progression. However, the extent of improvement and effect of ketoanalogue supplementation are unclear. We conducted a prospective, randomized, controlled trial of safety and efficacy of ketoanalogue-supplemented vegetarian very low-protein diet (KD) compared with conventional low-protein diet (LPD). Primary end point was RRT initiation or >50% reduction in initial eGFR. Nondiabetic adults with stable eGFR<30 ml/min per 1.73 m(2), proteinuria <1 g/g urinary creatinine, good nutritional status, and good diet compliance entered a run-in phase on LPD. After 3 months, compliant patients were randomized to KD (0.3 g/kg vegetable proteins and 1 cps/5 kg ketoanalogues per day) or continue LPD (0.6 g/kg per day) for 15 months. Only 14% of screened patients patients were randomized, with no differences between groups. Adjusted numbers needed to treat (NNTs; 95% confidence interval) to avoid composite primary end point in intention to treat and per-protocol analyses in one patient were 4.4 (4.2 to 5.1) and 4.0 (3.9 to 4.4), respectively, for patients with eGFR<30 ml/min per 1.73 m(2) Adjusted NNT (95% confidence interval) to avoid dialysis was 22.4 (21.5 to 25.1) for patients with eGFR<30 ml/min per 1.73 m(2) but decreased to 2.7 (2.6 to 3.1) for patients with eGFR<20 ml/min per 1.73 m(2) in intention to treat analysis. Correction of metabolic abnormalities occurred only with KD. Compliance to diet was good, with no changes in nutritional parameters and no adverse reactions. Thus, this KD seems nutritionally safe and could defer dialysis initiation in some patients with CKD.

Serum Anion Gap Predicts All-Cause Mortality in Patients with Advanced Chronic Kidney Disease: A Retrospective Analysis of a Randomized Controlled Study

Background and Objectives

Cardiovascular outcomes and mortality rates are poor in advanced chronic kidney disease (CKD) patients. Novel risk factors related to clinical outcomes should be identified.

Methods

A retrospective analysis of data from a randomized controlled study was performed in 440 CKD patients aged > 18 years, with estimated glomerular filtration rate 15–60 mL/min/1.73m². Clinical data were available, and the albumin-adjusted serum anion gap (A-SAG) could be calculated. The outcome analyzed was all-cause mortality.

Results

Of 440 participants, the median (interquartile range, IQR) follow-up duration was 5.1 (3.0–5.5) years. During the follow-up duration, 29 participants died (all-cause mortality 6.6%). The area under the receiver operating characteristic curve of A-SAG for all-cause mortality was 0.616 (95% CI 0.520–0.712, P = 0.037). The best threshold of A-SAG for all-cause mortality was 9.48 mmol/L, with sensitivity 0.793 and specificity 0.431. After adjusting for confounders, A-SAG above 9.48 mmol/L was independently associated with increased risk of all-cause mortality, with hazard ratio 2.968 (95% CI 1.143–7.708, P = 0.025). In our study, serum levels of beta-2 microglobulin and blood urea nitrogen (BUN) were positively associated with A-SAG.

Conclusions

A-SAG is an independent risk factor for all-cause mortality in advanced CKD patients. The positive correlation between A-SAG and serum beta-2 microglobulin or BUN might be a potential reason. Future study is needed.

Trial Registration

Clinicaltrials.gov NCT 00860431

Soy-based renoprotection

Chronic kidney disease (CKD) is a significant public health problem as risk factors such as advanced age, obesity, hypertension and diabetes rise in the global population. Currently there are no effective pharmacologic treatments for this disease. The role of diet is important for slowing the progression of CKD and managing symptoms in later stages of renal insufficiency. While low protein diets are generally recommended, maintaining adequate levels of intake is critical for health. There is an increasing appreciation that the source of protein may also be important. Soybean protein has been the most extensively studied plant-based protein in subjects with kidney disease and has demonstrated renal protective properties in a number of clinical studies. Soy protein consumption has been shown to slow the decline in estimated glomerular filtration rate and significantly improve proteinuria in diabetic and non-diabetic patients with nephropathy. Soy’s beneficial effects on renal function may also result from its impact on certain physiological risk factors for CKD such as dyslipidemia, hypertension and hyperglycemia. Soy intake is also associated with improvements in antioxidant status and systemic inflammation in early and late stage CKD patients. Studies conducted in animal models have helped to identify the underlying molecular mechanisms that may play a role in the positive effects of soy protein on renal parameters in polycystic kidney disease, metabolically-induced kidney dysfunction and age-associated progressive nephropathy. Despite the established relationship between soy and renoprotection, further studies are needed for a clear understanding of the role of the cellular and molecular target(s) of soy protein in maintaining renal function.

Nutrition Intervention for Advanced Stages of Diabetic Kidney Disease

IN BRIEF For the goals of reducing diabetic kidney disease (DKD) onset and progression, approaches to nutritional therapy are a subject of much debate. This article discusses selected nutrients that have a role in affecting DKD outcomes and introduces application of newer, individualized concepts for healthful eating, as supported by clinical evidence relevant to patients with DKD. Selected aspects of management of advanced DKD are also reviewed.

Contextual poverty, nutrition, and chronic kidney disease

Nutrition plays an important role in CKD outcomes. One of the strongest factors that affects nutrition is socioeconomic status as evidenced by the large body of epidemiologic data showing that income and education are directly associated with diet quality. Apart from individual-level markers of socioeconomic status such as income and education, contextual factors such as availability of and transportation to food outlets that provide healthy food options and the density of fast-food restaurants within particular regions markedly affect the ability of individuals to comply with nutrition recommendations. This is particularly true for nutrition guidelines most specific to individuals with CKD such as the consumption of protein, saturated fat, sodium, and phosphorus, all of which have been shown to affect CKD health and are influenced by the availability of healthy food options within individual neighborhood food environments. Because of the strong association of contextual poverty with the diet quality, any serious attempt to improve the diet of CKD patients must include a discussion of the environmental barriers that each individual faces in trying to access healthy foods, and health care providers should take account of these barriers when tailoring specific recommendations.

The incremental treatment of ESRD: a low-protein diet combined with weekly hemodialysis may be beneficial for selected patients

BACKGROUND

Infrequent dialysis, namely once-a-week session combined with very low-protein, low-phosphorus diet supplemented with ketoacids was reported as a useful treatment schedule for ESRD patients with markedly reduced residual renal function but preserved urine output. This study reports our findings from the application of a weekly dialysis schedule plus less severe protein restriction (standard low-protein low-phosphorus diet) in stage 5 CKD patients with consistent dietary discipline.

METHODS

This is a multicenter, prospective controlled study, including 68 incident CKD patients followed in a pre-dialysis clinic with Glomerular Filtration Rate 5 to 10 ml/min/1.73/ m2 who became unstable on the only medical treatment. They were offered to begin a Combined Diet Dialysis Program (CDDP) or a standard thrice-a-week hemodialysis (THD): 38 patients joined the CDDP, whereas 30 patients chose THD. Patients were studied at baseline, 6 and 12 months; hospitalization and survival rate were followed-up for 24 months.

RESULTS

Volume output and residual renal function were maintained in the CDDP Group while those features dropped quickly in THD Group. Throughout the study, CDDP patients had a lower erythropoietin resistance index, lower β2 microglobulin levels and lower need for cinacalcet of phosphate binders than THD, and stable parameters of nutritional status. At 24 month follow-up, 39.4% of patients were still on CDDP; survival rates were 94.7% and 86.8% for CDDP and THD patients, respectively, but hospitalization rate was much higher in THD than in CDDP patients. The cost per patient per year resulted significantly lower in CDDP than in THD Group.

CONCLUSIONS

This study shows that a CDDP served to protect the residual renal function, to maintain urine volume output and to preserve a good nutritional status. CDDP also blunted the rapid β2 microglobulin increase and resulted in better control of anemia and calcium-phosphate abnormalities. CDDP was also associated with a lower hospitalization rate and reduced need of erythropoietin, as well as of drugs used for treatment of calcium-phosphate abnormalities, thus leading to a significant cost-saving. We concluded that in selected ESRD patients with preserved urine output attitude to protein restriction, CDDP may be a beneficial choice for an incremental hemodialysis program.

Low protein diet inhibits uric acid synthesis and attenuates renal damage in streptozotocin-induced diabetic rats

AIM

Several studies indicated that hyperuricemia may link to the worsening of diabetic nephropathy (DN). Meanwhile, low protein diet (LPD) retards exacerbation of renal damage in chronic kidney disease. We then assessed whether LPD influences uric acid metabolism and benefits the progression of DN in streptozotocin- (STZ-) induced diabetic rats.

METHODS

STZ-induced and control rats were both fed with LPD (5%) and normal protein diet (18%), respectively, for 12 weeks. Vital signs, blood and urinary samples for UA metabolism were taken and analyzed every 3 weeks. Kidneys were removed at the end of the experiment.

RESULTS

Diabetic rats developed into constantly high levels of serum UA (SUA), creatinine (SCr) and 24 h amounts of urinary albumin excretion (UAE), creatinine (UCr), urea nitrogen (UUN), and uric acid (UUA). LPD significantly decreased SUA, UAE, and blood glucose, yet left SCr, UCr, and UUN unchanged. A stepwise regression showed that high UUA is an independent risk factor for DN. LPD remarkably ameliorated degrees of enlarged glomeruli, proliferated mesangial cells, and hyaline-degenerated tubular epithelial cells in diabetic rats. Expression of TNF-α in tubulointerstitium significantly decreased in LPD-fed diabetic rats.

CONCLUSION

LPD inhibits endogenous uric acid synthesis and might accordingly attenuate renal damage in STZ-induced diabetic rats.

Feline CKD

Practical relevance:

Chronic kidney disease (CKD) is common in humans as well as in cats, and is a significant human health problem. In feline medicine, despite recent research and improvements in our understanding of the condition, management remains limited by late diagnosis and an inadequate ability to prevent progression of disease. Investigation of future treatments that both delay the progression of CKD and manage clinical signs, and that are also easy and cost effective to administer, is desirable. To this end, we may learn from our colleagues in the medical profession.

Audience:

CKD is commonly encountered in general practice and so all practitioners dealing with cats will benefit from understanding future treatment possibilities and interventions in the management of CKD.

Evidence base:

Large-scale medical studies have been performed to provide an evidence base for treatment decisions in human CKD. Several studies in cats have looked at various aspects of treatment and prognosis, but large-scale studies are needed to assess the benefits of treatments such as angiotensin-converting enzyme inhibitors and angiotensin receptor blockers.

Clinical challenges:

Providing treatment that is effective, easy to administer and not cost-prohibitive is the challenge currently faced by clinicians in the management of feline CKD.