Fruit and Vegetable Treatment of Chronic Kidney Disease-Related Metabolic Acidosis Reduces Cardiovascular Risk Better than Sodium Bicarbonate

Citrate-based dietary alkali supplements available in Germany: an overview

BACKGROUND

Fruits and vegetables are abundant in alkali precursors and effectively reduce the Potential Renal Acid Load (PRAL) from diet. Oral alkali supplements are supposed to exert comparable alkalizing effects on the human body, and have been shown to beneficially affect bone and kidney health. A comparative analysis of the available dietary alkali supplements in Germany was performed, contrasting their potential PRAL-lowering potential.

METHODS

We reviewed the currently available dietary citrate-based alkali supplements sold in Germany with a special focus on their mineral content, their PRAL-lowering potential and other characteristics inherent to each product. Supplements containing either potassium-, calcium- or magnesium citrate or any combination of these organic salts were reviewed. The total alkali load (TAL) was calculated based on the recommended daily dosage (RDD).

RESULTS

Sixteen supplements with a mean alkali powder content of 220.69 ± 111.02 g were identified. The mean magnesium content per RDD was 239.93 ± 109.16 mg. The mean potassium and median calcium content were 550 ± 325.58 mg and 280 (240) mg, respectively. Median TAL was 1220 (328.75) mg. The PRAL-lowering potential from a single RDD ranged from - 51.65 mEq to -8.32 mEq. Substantial price differences were found, and the mean price of the examined supplements was 16.67 ± 5.77 Euros. The median price for a 1 mEq PRAL-reduction was 3.01 (3.14) cents, and ranged from 0.77 cents to 10.82 cents.

CONCLUSIONS

Noticeable differences between the identified alkali supplements were encountered, warranting an individual and context-specific approach in daily clinical practice.

Chronic Kidney Disease Diets for Kidney Failure Prevention: Insights from the IL-11 Paradigm

Nearly every fifth adult in the United States and many older adults worldwide are affected by chronic kidney disease (CKD), which can progress to kidney failure requiring invasive kidney replacement therapy. In this review, we briefly examine the pathophysiology of CKD and discuss emerging mechanisms involving the physiological resolution of kidney injury by transforming growth factor beta 1 (TGFβ1) and interleukin-11 (IL-11), as well as the pathological consequences of IL-11 overproduction, which misguides repair processes, ultimately culminating in CKD. Taking these mechanisms into account, we offer an overview of the efficacy of plant-dominant dietary patterns in preventing and managing CKD, while also addressing their limitations in terms of restoring kidney function or preventing kidney failure. In conclusion, this paper outlines novel regeneration strategies aimed at developing a reno-regenerative diet to inhibit IL-11 and promote repair mechanisms in kidneys affected by CKD.

The Role of Dietary Acid Load on Progression of Estimated Glomerular Filtration Rate Among Individuals Diagnosed With Chronic Kidney Disease

OBJECTIVE

Individuals with chronic kidney disease (CKD) are at an increased risk for developing metabolic acidosis. Metabolic acidosis has been shown to worsen kidney function and exacerbate systemic inflammation. Diets high in protein foods can exacerbate metabolic acidosis as protein foods tend to be more acidic, while fruits and vegetables are more alkalotic. The main objective of this systematic review was to determine if higher consumption of fruits and vegetables in adults with CKD stages 1-5 reduces the rate of decline of estimated glomerular filtration rate.

METHODS

Searches of Cumulated Index to Nursing and Allied Health Literature (CINAHL -Elton B. Stephens Company [EBSCO]), Cochrane Library (Wiley), Dissertation & Thesis Global (ProQuest), Embase (Elsevier), Medline (OVID), PubMed (National Library of Medicine), Scopus (Elsevier), and Web of Sciences (Clarivate) identified 1,451 articles published between January 2015 and June 2023.

RESULTS

After independent review, 7 total studies were included. Six of the studies found an association between dietary acid load and progression of CKD.

CONCLUSIONS

Dietary counseling focusing on decreasing dietary acid load may be beneficial for individuals with CKD.

Dieta de la Milpa: A Culturally-Concordant Plant-Based Dietary Pattern for Hispanic/Latine People with Chronic Kidney Disease

Chronic kidney disease (CKD) disproportionately affects minorities in the United States, including the Hispanic/Latine population, and is a public health concern in Latin American countries. An emphasis on healthy dietary patterns, including the Mediterranean and the Dietary Approaches to Stop Hypertension (DASH) diets, has been suggested as they are associated with a lower incidence of CKD, slower CKD progression, and lower mortality in kidney failure. However, their applicability may be limited in people from Latin America. The Dieta de la Milpa (Diet of the Cornfield) was recently described as the dietary pattern of choice for people from Mesoamerica (Central Mexico and Central America). This dietary pattern highlights the intake of four plant-based staple foods from this geographical region, corn/maize, common beans, pumpkins/squashes, and chilies, complemented with seasonal and local intake of plant-based foods and a lower intake of animal-based foods, collectively classified into ten food groups. Limited preclinical and clinical studies suggest several health benefits, including cardiometabolic health, but there is currently no data concerning CKD. In this narrative review, we describe and highlight the potential benefits of the Dieta de la Milpa in CKD, including acid-base balance, protein source, potassium and phosphorus management, impact on the gut microbiota, inflammation, and cultural appropriateness. Despite these potential benefits, this dietary pattern has not been tested in people with CKD. Therefore, we suggest key research questions targeting measurement of adherence, feasibility, and effectiveness of the Dieta de la Milpa in people with CKD.

Higher Renal Net Acid Excretion, but Not Higher Phosphate Excretion, during Childhood and Adolescence Associates with the Circulating Renal Tubular Injury Marker Interleukin-18 in Adulthood

High dietary phosphorus intake (P-In) and high acid loads may adversely affect kidney function. In animal models, excessive phosphorus intake causes renal injury, which, in humans, is also inducible by chronic metabolic acidosis. We thus examined whether habitually high P-In and endogenous acid production during childhood and adolescence may be early indicators of incipient renal inflammatory processes later in adulthood. P-In and acid-base status were longitudinally and exclusively determined by biomarker-based assessment in 277 healthy children, utilizing phosphate and net acid excretion (NAE) measurements in 24 h urine samples repeatedly collected between the ages of 3 and 17 years. Standard deviation scores (by sex and age) were calculated for anthropometric data and for the urinary biomarkers available within age range 3-17 years. Multivariable linear regression was used to analyze the relations of phosphate excretion and NAE with the adulthood outcome circulating interleukin-18 (IL-18), a marker of inflammation and kidney dysfunction. After adjusting for growth- and adulthood-related covariates and pro-inflammatory biomarkers to rule out confounding by non-renal inflammatory processes, regression models revealed a significant positive relationship of long-term NAE (p = 0.01), but not of long-term phosphate excretion with adult serum IL-18. Similar significant positive regression results were obtained after replacing NAE with 24 h urinary ammonium excretion as the exposition variable. Our results suggest that even moderate elevations in renal ammonia production, as caused by habitually higher acid loading during growth, may affect the intrarenal pro-inflammatory system in the long-term, known to be boosted by acidosis-induced raised ammoniagenesis.

Risks of the ketogenic diet in CKD - the con part

The ketogenic diet is a very low carbohydrate diet that has received a lot of attention for its role in the treatment of type 2 diabetes and obesity. For patients with chronic kidney disease, there is limited evidence on the risks and/or benefits of this diet. However, from the limited evidence that does exist, there are several inferences that can be drawn regarding this diet for patients with kidney disease. The ketogenic diet may not be better than comparator higher carbohydrate diets over the long term. The diet also has low adherence levels in studies lasting ≥12 months. The diet's emphasis on fat, which often comes from animal fat, increases the consumption of saturated fat, which may increase the risk of heart disease. It has the potential to worsen metabolic acidosis by increasing dietary acid load and endogenous acid production through the oxidation of fatty acids. In addition, the diet has been associated with an increased risk of kidney stones in patients using it for the treatment of refractory epilepsy. For these reasons, and for the lack of safety data on it, it is reasonable for patients with kidney disease to avoid utilizing the ketogenic diet as a first-line option given alternative dietary patterns (like the plant-dominant diet) with less theoretical risk for harm. For those adopting the ketogenic diet in kidney disease, a plant-based version of the ketogenic diet may mitigate some of the concerns with animal-based versions of the ketogenic diet.

Re-Thinking Hyperkalaemia Management in Chronic Kidney Disease-Beyond Food Tables and Nutrition Myths: An Evidence-Based Practice Review

Potassium dysregulation can be life-threatening. Dietary potassium modification is a management strategy for hyperkalaemia. However, a 2017 review for clinical guidelines found no trials evaluating dietary restriction for managing hyperkalaemia in chronic kidney disease (CKD). Evidence regarding dietary hyperkalaemia management was reviewed and practice recommendations disseminated. A literature search using terms for potassium, hyperkalaemia, and CKD was undertaken from 2018 to October 2022. Researchers extracted data, discussed findings, and formulated practice recommendations. A consumer resource, a clinician education webinar, and workplace education sessions were developed. Eighteen studies were included. Observational studies found no association between dietary and serum potassium in CKD populations. In two studies, 40-60 mmol increases in dietary/supplemental potassium increased serum potassium by 0.2-0.4 mmol/L. No studies examined lowering dietary potassium as a therapeutic treatment for hyperkalaemia. Healthy dietary patterns were associated with improved outcomes and may predict lower serum potassium, as dietary co-factors may support potassium shifts intracellularly, and increase excretion through the bowel. The resource recommended limiting potassium additives, large servings of meat and milk, and including high-fibre foods: wholegrains, fruits, and vegetables. In seven months, the resource received > 3300 views and the webinar > 290 views. This review highlights the need for prompt review of consumer resources, hospital diets, and health professionals' knowledge.

The Fruit and Veggies for Kidney Health Study: A Prospective Randomized Trial

Rationale & Objective

Providing fruits and vegetables (F&Vs) to health care system patients with elevated urine albumin-creatinine ratio (ACR) reduced ACR, slowed chronic kidney disease (CKD) progression and reduced cardiovascular disease (CVD) risk factors in previous studies. This study evaluated a community-based strategy in lower-income populations to identify African Americans with elevated ACR before health care system involvement and sustain them in a 6-month F&V protocol with (F&V + Cook) and without (F&V Only) cooking instructions, with the hypothesis that adjuvant cooking instructions with F&Vs would further reduce ACR.

Study Design

Prospective, randomized, parallel 2-arm design.

Setting & Participants

African American adults with ACR >10 mg/g creatinine randomized to 1 of 2 study arms.

Interventions

Two cups/day of F&Vs with or without cooking instructions in participants followed 6 months.

Outcomes

Participants sustaining the F&V protocol and between-group indicators of CVD risk, kidney injury, and dietary intake at 6 weeks and 6 months.

Results

A total of 142 African American adults (mean age, 57.0 years; ACR, 27.4 mg/g; body mass index, 34.4; 24.9% CKD 1; 24.8% CKD 2; 50.4% CKD 3; 55% female) randomized to F&V Only (n=72) or F&V + Cook (n=70), and 71% were retained at 6 months. Participants received 90% of available F&V pick-ups over 6 weeks and 69% over 6 months. In the adjusted model, 6-month ACR was 31% lower for F&V + Cook than F&V Only (P = 0.02). Net 6-week F&V intake significantly increased and biometric variables improved for participants combined into a single group.

Limitations

Small sample size, low-baseline ACR, and potential nonresponse bias for 24-hour dietary recall measure.

Conclusions

These data support the feasibility of identifying community-dwelling African Americans with ACR indicating elevated CVD and CKD risk and sustaining a F&V protocol shown to improve kidney outcomes and CVD risk factors and provides preliminary evidence that cooking instructions adjuvant to F&Vs are needed to lower ACR.

Funding

National Institute on Diabetes, Digestive, and Kidney Diseases grant "Reducing chronic kidney disease burden in an underserved population" (R21DK113440).

Trial Registration

NCT03832166.

Plain-Language Summary

African Americans, particularly those in low-income communities, have increased rates of chronic kidney disease (CKD) with worsening outcomes over time. Giving fruits and vegetables to individuals with CKD identified in health care systems was previously shown to reduce kidney damage, measured by urine protein albumin, and slow kidney function decline. We recruited African Americans in low-income communities with increased urine albumin levels. They received fruits and vegetables for 6 months, and we tested whether added cooking instructions further reduced urine albumin levels. Most participants continued to receive fruits and vegetables throughout the 6 months. Those given cooking instructions had lower urine albumin levels after 6 months, indicating decreased kidney damage. Providing cooking instructions with fruits and vegetables appears to lessen kidney damage more than just fruits and vegetables alone.

Association between healthy eating index-2015 and abdominal aortic calcification: A population-based cross-sectional study

Background

An association between the healthy eating index (HEI)-2015 and risk of abdominal aortic calcification (AAC) is unclear in the general population of the United States (U.S.). Therefore, we examined the relationship between HEI-2015 and AAC risk in our research.

Methods

A cross-sectional study of National Health and Nutrition Examination Surveys (NHANES) participants between 2013 and 2014 was conducted. For the analysis of the association between HEI-2015 and AAC, the restricted cubic spline (RCS) plot and multivariable logistic regression models were used. In addition, we also conducted subgroup analysis for the relationship between HEI-2015 and AAC.

Results

There was a total of 1162 individuals. As shown by the RCS plot, HEI-2015 was linked with AAC risk in a U-shaped pattern (P for nonlinearity < 0.05). Taking into account known confounding variables, compared with the lowest quartiles, the odds ratios with 95% confidence intervals for AAC across the quartiles were 0.637 (0.425,0.956), 0.763 (0.499, 1.167), and 0.842 (0.561, 1.265). Based on the results of subgroup analysis, the HEI-2015 and AAC risk were U-curve correlated among all age groups, sex, with or without hypertension or DM, and BMI of <30 kg/m2. The greens and beans, and whole fruits are independent protective factor for AAC.

Conclusions

The U-shaped relationships exist between HEI-2015 and prevalence of AAC in the general U.S. population. Consequently, prevalence of AAC may be mitigated with reasonable and balanced diet.

New Insights Into Dietary Approaches to Potassium Management in Chronic Kidney Disease

Potassium disorders are one of the most common electrolyte abnormalities in patients with chronic kidney disease (CKD), contributing to poor clinical outcomes. Maintaining serum potassium levels within the physiologically normal range is critically important in these patients. Dietary potassium restriction has long been considered a core strategy for the management of chronic hyperkalemia in patients with CKD. However, this has been challenged by recent evidence suggesting a paradigm shift toward fostering more liberalized, plant-based dietary patterns. The advent of novel potassium binders and an improved understanding of gastrointestinal processes involved in potassium homeostasis (e.g., gastrointestinal potassium wasting) may facilitate a paradigm shift and incorporation of heart-healthy potassium-enriched food sources. Nevertheless, uncertainty regarding the risk-benefit of plant-based diets in the context of potassium management in CKD remains, requiring well-designed clinical trials to determine the efficacy of dietary potassium manipulation toward improvement of clinical outcomes in patients with CKD.

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.

Association of Plant-Based Protein Intake with Cognitive Function in Adults with CKD

Key Points

Higher plant protein intake was associated with higher cognitive scores in people with kidney disease. Future trials are needed to determine whether increasing plant protein intake improves measures of cognition in patients with kidney disease.

Background

Patients with CKD have accelerated cardiovascular and cognitive aging when compared with the non-CKD population. This cognitive decline contributes to excessive rates of physical and functional decline, reduced quality of life, and mortality in the CKD population. Mediterranean diets, a plant-forward diet, have been associated with positive cognitive performance in the general non-CKD population and with some beneficial outcomes in CKD. However, it is still unclear whether plant-based diets are associated with cognitive decline in patients with CKD.

Methods

Using the National Health and Nutrition Examination Survey 2011–2012 and 2013–14 data, we conducted a secondary analysis evaluating the relationship of plant-based and unprocessed plant protein with cognitive outcome measures in eligible participants aged 60 years and older. All data were extracted from the available National Health and Nutrition Examination Survey demographic, questionnaire, examination, and laboratory data. CKD was calculated and defined in participants as urine albumin to creatinine ratio ≥30 mg/g and/or eGFR <60 ml/min. In incremental models, we adjusted for total energy intake, age, sex, race/ethnicity, body mass index, total energy intake, diabetes, hypertension, education, smoking, and alcohol.

Results

Higher plant-based protein above median dietary intakes was significantly associated with higher executive function scores in participants with CKD (P < 0.05). For all patients and in those with CKD, plant-based protein was significantly associated (P < 0.05) with higher composite cognitive scores in nearly all statistical models. Higher unprocessed plant protein was significantly associated (P < 0.05) with higher composite cognitive scores in all categorical models.

Conclusions

Higher plant protein intake was a significant predictor of certain individual and composite cognitive score measures within the general and in the CKD population. Future interventional trials are needed to determine whether increasing plant-based protein intake improves measures of cognition in patients with CKD.

Mediterranean Diet for Cardiovascular Risk Reduction in Chronic Kidney Disease

The Mediterranean diet is a plant-based healthy diet similar to the vegetarian and the Dietary Approaches to Stop Hypertension diets. Unlike vegetarian and Dietary Approaches to Stop Hypertension diets, the Mediterranean diet encourages a lifestyle associated with physical activity, and social connections. In addition, the Mediterranean diet is not based on restriction of nutrients but does limit intake of processed foods. Prospective studies have confirmed that the Mediterranean diet confers primary and secondary cardiovascular disease prevention in the general population. The benefits of the Mediterranean diet lifestyle include reducing the risk of diabetes mellitus, dyslipidemia, and lowers blood pressure. In adults with CKD, adherence to the Mediterranean diet is associated with a lower risk of CKD progression and its complications such as hyperphosphatemia and metabolic acidosis, and reduces production of uremic toxins and inflammatory mediators when compared to omnivore dietary patterns. Nevertheless, prospective studies are needed to confirm the cardiovascular disease prevention with the Mediterranean diet in adults with CKD. Medical nutrition therapy remains a cornerstone of CKD management, and the Mediterranean diet could be utilized to slow CKD progression and complications.

The effects of oral sodium bicarbonate supplementation on anthropometric measures in patients with chronic kidney disease: A systematic review and meta-analysis of randomized clinical trials

Metabolic acidosis (MA) may play a key role in the pathogenesis of protein-energy wasting (PEW) in patients with chronic kidney disease (CKD). To present a comprehensive synthesis of the effect of oral sodium bicarbonate (SB) supplementation on anthropometric measures in patients with CKD, a systematic review was undertaken in PubMed/MEDLINE, Web of Science, Cochrane CENTRAL, and Google Scholar, of relevant articles published prior to September 2022. The summary statistics of effect size, nonstandardized weighted mean difference (WMD), and 95% confidence interval (CI) were used to compare the effects of SB supplementation on anthropometric parameters vs. control group. To detect probable sources of heterogeneity, a series of predefined subgroup analyses were conducted. In total, 17 studies with 21 treatment arms, including 2203 participants (1149 cases, 1054 controls), met our inclusion criteria and were included in the meta-analysis. SB supplementation had no significant effect on body weight (BW), midarm muscle circumference (MAMC), or lean body mass (LBM) in patients with CKD. There was a significant increase in body mass index (BMI) (MD: 0.59 kg/m2, 95% CI: 0.25 to 0.93, p = 0.001) after SB supplementation in the overall analysis. In subgroup analysis, LBM was increased in studies that were ≥ 24-week duration (MD: 1.81 kg, 95% CI: 0.81 to 2.81) and in participants with BMI lower than 27 kg/m2 (MD: 1.81 mg/L, 95% CI: 0.81 to 2.81). SB supplementation may yield increases in BMI in predialysis CKD patients. However, our findings did not support the beneficial effects of SB supplementation on other anthropometric outcomes. There is an evident need for long-term high-quality interventions to confirm these findings.

The Role of Plant-Based Diets in Preventing and Mitigating Chronic Kidney Disease: More Light than Shadows

Chronic kidney disease (CKD) is a non-communicable disease that affects >10% of the general population worldwide; the number of patients affected by CKD is increasing due in part to the rise in risk factors such as obesity, hypertension, and diabetes mellitus. As many studies show, diet can be an important tool for preventing and mitigating the onset of non-communicable diseases. Plant-based diets (PBDs) are those that emphasize the consumption of plant foods and may or may not include small or moderate amounts of animal foods. Recently, these diets have received increasing interest because they have been associated with favourable effects on health and also appear to protect against the development and progression of CKD. PBDs, which are associated with protein restrictions, seem to offer adjunctive advantages in patients with chronic kidney disease, as compared to conventional low-protein diets that include animal proteins. The principal aims of this review are to provide a comprehensive overview of the existing literature regarding the role of plant-based diets and low-protein, plant-based diets in the context of chronic kidney disease. Moreover, we try to clarify the definition of plant-based diets, and then we analyse possible concerns about the use of PBDs in patients with chronic kidney disease (nutritional deficiency and hyperkalaemia risk). Finally, we offer some strategies to increase the nutritional value of plant-based low-protein diets. In the Materials and Methods section, many studies about plant-based diets and low-protein plant-based diets (e.g., the very-low-protein diet and vegan low-protein diet, LPD) in chronic kidney disease were considered. In the Results and Conclusion section, current data, most from observational studies, agree upon the protective effect of plant-based diets on kidney function. Moreover, in patients with advanced CKD, low-protein plant-based options, especially a very-low-protein diet supplemented with heteroanalogues (VLPDs), compared to a conventional LPD appear to offer adjunctive advances in terms of delaying dialysis and mitigating metabolic disturbances. However, further studies are necessary to better investigate the possible metabolic and cardiovascular advantages of plant-based LPDs versus conventional LPDs.

The benefits of dietary fiber: the gastrointestinal tract and beyond

Dietary fiber is considered an essential constituent of a healthy child's diet. Diets of healthy children with adequate dietary fiber intake are characterized by a higher diet quality, a higher nutrient density, and a higher intake of vitamins and minerals in comparison to the diets of children with poor dietary fiber intake. Nevertheless, a substantial proportion of children do not meet the recommended dietary fiber intake. This is especially true in those children with kidney diseases, as traditional dietary recommendations in kidney diseases have predominantly focused on the quantities of energy and protein, and often restricting potassium and phosphate, while overlooking the quality and diversity of the diet. Emerging evidence suggests that dietary fiber and, by extension, a plant-based diet with its typically higher dietary fiber content are just as important for children with kidney diseases as for healthy children. Dietary fiber confers several health benefits such as prevention of constipation and fewer gastrointestinal symptoms, reduced inflammatory state, and decreased production of gut-derived uremic toxins. Recent studies have challenged the notion that a high dietary fiber intake confers an increased risk of hyperkalemia or nutritional deficits in children with kidney diseases. There is an urgent need of new studies and revised guidelines that address the dietary fiber intake in children with kidney diseases.

Reducing Dietary Acid With Fruit and Vegetables Versus Oral Alkali in People With Chronic Kidney Disease (ReDACKD): A Clinical Research Protocol

Background

Individuals with chronic kidney disease (CKD) can develop metabolic acidosis which, in turn, is associated with faster progression of CKD and an increased need for dialysis. Oral sodium bicarbonate (the current standard of care therapy for metabolic acidosis) is poorly tolerated leading to low adherence. Base-producing or alkalizing Fruit and vegetables have potential as an alternative treatment for metabolic acidosis as they have been shown to reduce acid load arising from the diet.

Objective

This trial will evaluate the feasibility of providing base-producing fruit and vegetables as a dietary treatment for metabolic acidosis, compared with oral sodium bicarbonate.

Design

A 2-arm, open-label, dual-center, randomized controlled feasibility trial.

Setting

Two Canadian sites: a nephrology clinic in Winnipeg, Manitoba, and a nephrology clinic in Halifax, Nova Scotia.

Participants

Adult participants with G3-G5 CKD and metabolic acidosis.

Measurements

Participants will undergo baseline measurements and attend 5 study visits over 12 months at which they will have a measurement of feasibility criteria as well as blood pressure, blood and urine biochemistry, 5-repetition chair stand test (STS5), and questionnaires to assess quality of life and symptoms. Furthermore, participants fill out Automated Self-Administered 24-hour recalls (ASA-24) in the beginning, middle, and end of trial.

Methods

A total of 40 eligible participants will be randomized 1:1 to either base-producing fruit and vegetables (experimental) group or sodium bicarbonate (control) group, beginning from a daily dose of 1500 mg.

Limitations

Using self-administered dietary assessments, lack of supervision over the consumption of study treatments and the possible disappointment of the control group for not receiving fruit and vegetables would be considered as limitations for this study. However, we are planning to undertake proper practices to overcome the possible limitations. These practices are discussed throughout the article in detail.

Conclusions

This study will generate data on base-producing fruit and vegetables consumption as a dietary treatment for metabolic acidosis in CKD. The data will be used to design a future multi-center trial looking at slowing CKD progression in people with metabolic acidosis.

Trial Registration

This study is registered on clinicaltrials.gov with the identifier NCT05113641.

Lifestyle Interventions, Kidney Disease Progression, and Quality of Life: A Systematic Review and Meta-analysis

Rationale & Objective

Poor dietary patterns and low physical activity levels are important lifestyle-related factors that contribute to negative health outcomes in individuals with chronic kidney disease (CKD). Previous systematic reviews have not explicitly focused on these lifestyle factors, nor undertaken meta-analyses of any effects. We aimed to evaluate the effect of lifestyle interventions (such as diet, exercise, and other lifestyle-related interventions) on the risk factors for and progression of CKD and the quality of life.

Study Design

Systematic review and meta-analysis.

Setting & Study Populations

Individuals aged 16 years or older with CKD stages 1 to 5 not requiring kidney replacement therapy.

Selection Criteria for Studies

Randomized controlled trials of interventions.

Data Extraction

Kidney function, albuminuria, creatinine, systolic blood pressure, diastolic blood pressure, body weight, glucose control, and quality of life.

Analytical Approach

A random-effects meta-analysis with evidence certainty assessed using GRADE.

Results

Seventy-eight records describing 68 studies were included. Twenty-four studies (35%) were dietary interventions, 23 (34%) exercise, 9 (13%) behavioral, 1 (2%) hydration, and 11 (16%) multiple component. Lifestyle interventions resulted in significant improvements in creatinine (weighted mean difference [WMD], -0.43 mg/dL; 95% CI, -0.74 to -0.11; P = 0.008); 24-hour albuminuria (WMD, -53 mg/24 h; 95% CI, -56 to -50; P < 0.001); systolic blood pressure (WMD, -4.5 mm Hg; 95% CI, -6.7 to -2.4; P < 0.001); diastolic blood pressure (WMD, -2.2 mm Hg; 95% CI, -3.7 to -0.8; P = 0.003); and body weight (WMD, -1.1 kg; 95% CI, -2.0 to -0.1; P = 0.025). Lifestyle interventions did not result in significant changes in the estimated glomerular filtration rate (0.9 mL/min/1.73 m²; 95% CI, -0.6 to 2.3; P = 0.251). However, narrative synthesis indicated that lifestyle intervention resulted in improvements in the quality of life.

Limitations

Certainty of the evidence was rated very low for most outcomes, primarily owing to the risk of bias and inconsistency. No meta-analysis was possible for quality-of-life outcomes because of variations in measurement tools.

Conclusions

Lifestyle interventions seem to positively affect some risk factors for progression of CKD and quality of life.

[Unintentional weight loss in chronic kidney disease]

If the causes of unintended weight loss are already diverse in pre-dialysis patients, at the stage of dialysis requirement a variety of other causes are added. Both stages share a trend towards loss of appetite and nausea, whereby uremic toxins certainly do not represent the only cause. In addition, both stages involve increased catabolism and therefore a higher calorie requirement. In the dialysis stage, protein loss (more in peritoneal dialysis than in hemodialysis) and the sometimes extensive dietary restrictions (low potassium, low phosphate, fluid restriction) are added. The problem of malnutrition, especially in dialysis patients, has been increasingly recognized in recent years, and there is a trend towards improvement. Initially, the causes of weight loss were subsumed under the terms protein energy wasting (PEW), which emphasized the protein loss in dialysis, and malnutrition-inflammation-atherosclerosis (MIA) syndrome, which highlighted chronic inflammation in dialysis patients; however, a variety of other factors contribute to weight loss, which are better described by the term chronic disease-related malnutrition (C-DRM). Weight loss is the most significant factor in recognizing malnutrition, as pre-existing obesity (especially type II diabetes mellitus) often makes the recognition more difficult. In the future, the increasing use of glucagon-like peptide 1 (GLP-1) agonists for weight loss could also lead to weight loss being perceived as intentional rather than distinguishing between intentional fat loss and unintentional loss of muscle mass.

Care of the Patient With Abnormal Kidney Test Results

Blood and urine tests are commonly performed by clinicians in both ambulatory and hospital settings that detect chronic and acute kidney disease. Thresholds for these tests have been established that signal the presence and severity of kidney injury or dysfunction. In the appropriate clinical context of a patient's history and physical examination, an abnormal test result should trigger specific actions for clinicians, including reviewing patient medication use, follow-up testing, prescribing lifestyle modifications, and specialist referral. Tests for kidney disease can also be used to determine the future risk for kidney failure as well as cardiovascular death.

Effect of Sodium Bicarbonate on Systolic Blood Pressure in CKD: A Systematic Review and Meta-Analysis

BACKGROUND

Individuals with CKD are at a higher risk of cardiovascular morbidity and mortality. Acidosis is positively correlated with CKD progression and elevated systolic BP. Sodium bicarbonate is an efficacious treatment of acidosis, although this may also increase systolic BP. In this systematic review and meta-analysis, we summarize the evidence evaluating systolic BP and antihypertensive medication change (which may indicate systolic BP change) in response to sodium bicarbonate therapy in individuals with CKD.

METHODS

Medical Literature Analysis and Retrieval System Online, Excerpta Medica database, Cumulative Index to Nursing and Allied Health Literature, Allied and Complementary Medicine Database, Cochrane Central Register of Controlled Trials, and World Health Organization (WHO) trials registry databases were searched for randomized control trials where sodium bicarbonate was compared with placebo/usual care in CKD stage G1-5 non-dialysis-dependent populations. Random effects meta-analyses were used to evaluate changes in systolic BP and BP-modifying drugs after sodium bicarbonate intervention.

RESULTS

Fourteen randomized control trials (2110 individuals, median follow-up 27 [interquartile range 97] weeks, mean age 60 [SD 10] years, mean systolic BP 136 [SD 17] mm Hg, mean eGFR 38 [SD 10] ml/min, mean serum bicarbonate 22 [SD 4] mmol/L) were eligible for inclusion. Meta-analysis suggested that sodium bicarbonate did not influence systolic BP in individuals with CKD stage G1-5. Results were consistent when stratifying by dose of sodium bicarbonate or duration of intervention. Similarly, there was no significant increase in the use of antihypertensive medication or diuretics in individuals taking sodium bicarbonate, whereas there was a greater decrease in antihypertensive medication use in individuals taking sodium bicarbonate compared with controls.

CONCLUSIONS

Our results suggest, with moderate certainty, that sodium bicarbonate supplementation does not adversely affect systolic BP in CKD or negatively influence antihypertensive medication requirements.

Gut Microbiota-Targeted Interventions in the Management of Chronic Kidney Disease

Recent advances in microbiome research have informed the potential role of the gut microbiota in the regulation of metabolic, cardiovascular, and renal systems, and, when altered, in the pathogenesis of various cardiometabolic disorders, including chronic kidney disease (CKD). The improved understanding of gut dysbiosis in cardiometabolic pathologies in turn has led to a vigorous quest for developing therapeutic strategies. These therapeutic strategies aim to investigate whether interventions targeting gut dysbiosis can shift the microbiota toward eubiosis and if these shifts, in turn, translate into improvements in (or prevention of) CKD and its related complications, such as premature cardiovascular disease. Existing evidence suggests that multiple interventions (eg, plant-based diets; prebiotic, probiotic, and synbiotic supplementation; constipation treatment; fecal microbiota transplantation; and intestinal dialysis) might result in favorable modulation of the gut microbiota in patients with CKD, and thereby potentially contribute to improving clinical outcomes in these patients. In this review, we summarize the current understanding of the characteristics and roles of the gut microbiota in CKD and discuss the potential of emerging gut microbiota-targeted interventions in the management of CKD.

Plant or Animal-Based or PLADO Diets: Which Should Chronic Kidney Disease Patients Choose?

Nutrition therapy is the cornerstone treatment for chronic kidney disease (CKD). Although much attention has been given to dietary protein intake in CKD patients, many findings now demonstrate that the type of dietary protein intake may be more critical for CKD patients. In protein bioavailability and malnutrition prevention, many physicians recommend that CKD patients adhere to a low protein diet and restrict their plant foods, such as vegetables, fruits, and soybeans. However, nephrologists should not ignore the potential benefits of plant foods for CKD patients. It is not advisable to restrict the intake of plant foods in the later stage of CKD simply to prevent the development of hyperkalemia and malnutrition. This article highlights the benefits and possible problems of a plant-dominant low protein diet (PLADO) diet, defined as an LPD with dietary protein intake of 0.6-0.8 g/kg/day with at least 50% plant-based source for CKD patients. We hope to provide new opinions for clinical work and CKD patients.

The Role of Dietary Potassium in the Cardiovascular Protective Effects of Plant-Based Diets

Dietary intervention is an essential factor in managing a multitude of chronic health conditions such as cardiovascular and chronic kidney disease. In recent decades, there has been a host of research suggesting the potential benefit of plant-based diets in mitigating the health outcomes of these conditions. Plant-based diets are rich in vegetables and fruits, while limiting processed food and animal protein sources. The underlying physiological mechanism involves the interaction of several macronutrients and micronutrients such as plant protein, carbohydrates, and dietary potassium. Specifically, plant-based foods rich in potassium provide cardiorenal protective effects to include urinary alkalization and increased sodium excretion. These diets induce adaptive physiologic responses that improve kidney and cardiovascular hemodynamics and improve overall metabolic health. A shift toward consuming plant-based diets even in subjects with cardiorenal decrements may reduce their morbidity and mortality. Nonetheless, randomized controlled trials are needed to confirm the clinical benefits of plant-based diets.

Lifestyle Modifications and Nutritional and Therapeutic Interventions in Delaying the Progression of Chronic Kidney Disease: A Review

Chronic kidney disease (CKD) is a debilitating progressive illness that affects more than 10% of the world's population. In this literature review, we discussed the roles of nutritional interventions, lifestyle modifications, hypertension (HTN) and diabetes mellitus (DM) control, and medications in delaying the progression of CKD. Walking, weight loss, low-protein diet (LPD), adherence to the alternate Mediterranean (aMed) diet, and Alternative Healthy Eating Index (AHEI)-2010 slow the progression of CKD. However, smoking and binge alcohol drinking increase the risk of CKD progression. In addition, hyperglycemia, altered lipid metabolism, low-grade inflammation, over-activation of the renin-angiotensin-aldosterone system (RAAS), and overhydration (OH) increase diabetic CKD progression. The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend blood pressure (BP) control of <140/90 mmHg in patients without albuminuria and <130/80 mmHg in patients with albuminuria to prevent CKD progression. Medical therapies aim to target epigenetic alterations, fibrosis, and inflammation. Currently, RAAS blockade, sodium-glucose cotransporter-2 (SGLT2) inhibitors, pentoxifylline, and finerenone are approved for managing CKD. In addition, according to the completed Study of Diabetic Nephropathy with Atrasentan (SONAR), atrasentan, an endothelin receptor antagonist (ERA), decreased the risk of renal events in diabetic CKD patients. However, ongoing trials are studying the role of other agents in slowing the progression of CKD.

Dietary Acid Load and Predialysis Serum Bicarbonate Levels in Patients With End-Stage Renal Disease

OBJECTIVES

Maintaining the predialysis serum bicarbonate at a recommended level is critical in patients undergoing hemodialysis. Therefore, the present study investigated the association between dietary acid load (DAL) and serum predialysis bicarbonate levels in patients with end-stage renal disease.

METHODS

Adult patients undergoing hemodialysis were enrolled in this cross-sectional study. Diet was assessed using a semiquantitative food frequency questionnaire. DAL was calculated with 2 validated indices: potential renal acid load (PRAL) and net endogenous acid production (NEAP). Values regarding predialysis serum bicarbonate level and serum electrolytes were obtained from the participant's medical records. The multiple linear regression analysis was used to determine the association between DAL indices and predialysis serum bicarbonate level.

RESULTS

The number of hemodialysis patients eligible for this study was 122. The participants' mean age and body mass index was 57.14 ± 3.8 years and 25.2 ± 4.9 kg/m², respectively. About 65.6% of participants were male. The mean serum levels of predialysis bicarbonate were 21.59 ± 3.1 mEq/L. Also, 47.5% of patients had predialysis serum bicarbonate levels below the recommended value. The mean values of PRAL and NEAP were -2.8 ± 7.48 and 42.7 ± 10.1 mEq/day, respectively. PRAL significantly and inversely predicted predialysis serum bicarbonate level independent of covariates (standardized β = -0.38; P < .001). Also, NEAP was independently and inversely associated with predialysis bicarbonate level (standardized β = -0.40; P < .001). Consuming vegetables such as lettuce, tomato, cucumber, spinach, and dried fruits as well as low-fat milk, plain yogurt, and cream cheese were positively correlated to predialysis serum bicarbonate level. However, the canned tuna had a negative correlation with the predialysis serum bicarbonate.

CONCLUSIONS

The study's findings showed that the lower DAL was associated with higher predialysis serum bicarbonate levels in patients with end-stage renal disease. Due to the cross-sectional nature of the present study, prospective cohorts or well-controlled clinical trials are needed to confirm our result.

Patterns of Fruit and Vegetable Intake in Adults With and Without Chronic Kidney Disease in the United States

OBJECTIVE

To characterize patterns of fruit and vegetable (F&V) intake in US adults with and without chronic kidney disease (CKD).

METHODS

We used 24-hour dietary recall data from multiple cycles of the National Health and Nutrition Examination Survey spanning 3 groups from 1988 to 2018 (1988-1994; 2003-2010; 2011-2018). We categorized F&Vs based on food processing and phytochemical content. We assessed patterns of F&Vs using latent class analysis and compared intake patterns across the 3 temporal cohorts and CKD status using weighted multinomial logistic regression.

RESULTS

Four similar patterns of F&Vs emerged in each cycle: Overall Low Intake, High Unprocessed, High Ultra-Processed, and Moderate Processed F&Vs. The Overall Low Intake pattern was most prevalent in all cohorts and CKD groups. After adjustment for demographic variables and selected health conditions, participants with compared to without CKD were more likely to be classified as Overall Low Intake in each cohort, although this was not significant in the National Health and Nutrition Examination Survey 2011-2018.

CONCLUSIONS

Low consumption of F&Vs was more common in patients with CKD. Longitudinal studies are needed to determine if low intake is a risk factor for, or response to, CKD.

Observational and clinical evidence that plant-based nutrition reduces dietary acid load

Contemporary diets in Western countries are largely acid-inducing and deficient in potassium alkali salts, resulting in low-grade metabolic acidosis. The chronic consumption of acidogenic diets abundant in animal-based foods (meats, dairy, cheese and eggs) poses a substantial challenge to the human body's buffering capacities and chronic retention of acid wherein the progressive loss of bicarbonate stores can cause cellular and tissue damage. An elevated dietary acid load (DAL) has been associated with systemic inflammation and other adverse metabolic conditions. In this narrative review, we examine DAL quantification methods and index observational and clinical evidence on the role of plant-based diets, chiefly vegetarian and vegan, in reducing DAL. Quantitation of protein and amino acid composition and of intake of alkalising organic potassium salts and magnesium show that plant-based diets are most effective at reducing DAL. Results from clinical studies and recommendations in the form of expert committee opinions suggest that for a number of common illnesses, wherein metabolic acidosis is a contributing factor, the regular inclusion of plant-based foods offers measurable benefits for disease prevention and management. Based on available evidence, dietary shifts toward plant-based nutrition effectively reduces dietary-induced, low-grade metabolic acidosis.

New mechanisms for the kidney-protective effect of alkali in chronic kidney disease

Worldwide, more than one in ten adults are estimated to have chronic kidney disease (CKD). As CKD progresses, both the cost of treatment and associated risk of morbidity and mortality increase exponentially. As such, there is a great need for therapies that effectively slow CKD progression. Evidence from several small clinical trials indicates that alkali therapy may slow the rate of CKD progression. The biological mechanisms underlying this protective effect, however, remain unknown. In their recently published manuscript, Pastor Arroyo et al. (Clin Sci (Lond) (2022) 136(8): https://doi.org/10.1042/CS20220095) demonstrate that the alkali sodium bicarbonate protects against loss of renal function in a crystal nephropathy model in mice. Using unbiased approaches in both mice and human tissue, the authors go on to identify two novel mechanisms that may underly this protection. The first pathway is through promoting pathways of cell metabolism, which they speculate helps the remaining functional nephrons adapt to the greater metabolic needs required to maintain kidney filtration. The second pathway is by restoration of α-Klotho levels, which may limit the expression of adhesion molecules in the injured kidney. This, the authors speculate, may prevent inflammation from driving the functional decline of the kidney. Identifying these novel pathways represents an important step forward harnessing the potential benefits of alkali therapy in CKD.

Management of Metabolic Acidosis in Chronic Kidney Disease: Past, Present, and Future Direction

Chronic kidney disease (CKD) is a major global epidemic associated with increased morbidity and mortality. Despite the effectiveness of kidney protection strategies of hypertension, diabetes, and lipid control and use of newer hypoglycemic agents and anti-angiotensin II drugs, the nephropathy in CKD continues unabated toward irreversible kidney failure. Thus, interventions targeting modifiable risk factors in CKD such as metabolic acidosis (MA) are needed. Acid reduction with sodium-based alkali has been shown to be an effective kidney-protection strategy for patients with CKD and reduced glomerular filtration rate (GFR). Small-scale studies reveal diets emphasizing ingestion of plant-sourced over animal-sourced protein reduce dietary acid, improve MA, and slow further nephropathy progression in patients with CKD and reduced GFR. Additionally, veverimer, an investigational, nonabsorbed polymer that binds and removes gastrointestinal hydrochloric acid, is being developed as a novel treatment for MA. As further studies define how to best use these interventions for kidney protection, clinicians must become aware of their potential utility in the management of patients with CKD. The aim of the present review is to explore the various intervention strategies that increase or normalize serum [HCO₃^-] in patients with CKD-associated MA or low normal serum [HCO₃^-] that may further slow progression of CKD.

Dietary Contributions to Metabolic Acidosis

Eating a net acid-producing diet can produce an "acid stress" of severity proportional to the diet net acid load, as indexed by the steady-state renal net acid excretion rate. Depending on how much acid or base is ingested or produced from endogenous metabolic processes and how well our homeostatic mechanisms can buffer or eliminate the additional acids or bases, we can alter our systemic acid-base balance. With increasing age, the kidney's ability to excrete daily net acid loads declines (a condition similar to that of mild CKD), invoking increased utilization of potential base stores (eg, bone, skeletal muscle) on a daily basis to mitigate the acid accumulation, thereby contributing to development of osteoporosis, loss of muscle mass, and age-related renal insufficiency. Patients suffering from more advanced CKD often present with more severe acid stress or metabolic acidosis, as the kidney can no longer excrete the entire acid load. Alkaline diets based on fruits and vegetables may have a positive effect on long-term preservation of renal function while maintaining nutritional status. This chapter discusses the biochemistry of dietary precursors that affect acid or base production.

Oral Acid Load Down-Regulates Fibroblast Growth Factor 23

Increased dietary acid load has a negative impact on health, particularly when renal function is compromised. Fibroblast growth factor 23 (FGF23) is a bone-derived hormone that is elevated during renal failure. The relationship between metabolic acidosis and FGF23 remains unclear. To investigate the effect of dietary acid load on circulating levels of FGF23, rats with normal renal function and with a graded reduction in renal mass (1/2 Nx and 5/6 Nx) received oral NH4Cl for 1 month. Acid intake resulted in a consistent decrease of plasma FGF23 concentrations in all study groups when compared with their non-acidotic control: 239.3 ± 13.5 vs. 295.0 ± 15.8 pg/mL (intact), 346.4 ± 19.7 vs. 522.6 ± 29.3 pg/mL (1/2 Nx) and 988.0 ± 125.5 vs. 2549.4 ± 469.7 pg/mL (5/6 Nx). Acidosis also decreased plasma PTH in all groups, 96.5 ± 22.3 vs. 107.3 ± 19.1 pg/mL, 113.1 ± 17.3 vs. 185.8 ± 22.2 pg/mL and 504.9 ± 75.7 vs. 1255.4 ± 181.1 pg/mL. FGF23 showed a strong positive correlation with PTH (r = 0.877, p < 0.0001) and further studies demonstrated that acidosis did not influence plasma FGF23 concentrations in parathyroidectomized rats, 190.0 ± 31.6 vs. 215 ± 25.6 pg/mL. In conclusion, plasma concentrations of FGF23 are consistently decreased in rats with metabolic acidosis secondary to increased acid intake, both in animals with intact renal function and with decreased renal function. The in vivo effect of metabolic acidosis on FGF23 appears to be related to the simultaneous decrease in PTH.

Effects of oral alkali drug therapy on clinical outcomes in pre-dialysis chronic kidney disease patients: a systematic review and meta-analysis

BACKGROUND

Metabolic acidosis accelerates the progression of chronic kidney disease (CKD) and increases the mortality rate. Whether oral alkali drug therapy benefits pre-dialysis CKD patients is controversial. We performed a meta-analysis of the effects of oral alkali drug therapy on major clinical outcomes in pre-dialysis CKD patients.

METHODS

We systematically searched MEDLINE using the Ovid, EMBASE, and Cochrane Library databases without language restriction. We included all eligible clinical studies that involved pre-dialysis CKD adults and compared those who received oral alkali drug therapy with controls.

RESULTS

A total of 18 eligible studies, including 14 randomized controlled trials and 4 cohort studies reported in 19 publications with 3695 participants, were included. Oral alkali drug therapy led to a 55% reduction in renal failure events (relative risk [RR]: 0.45; 95% confidence interval [CI]: 0.25-0.82), a rate of decline in the estimated glomerular filtration rate (eGFR) of 2.59 mL/min/1.73 m² per year (95% CI, 0.88-4.31). There was no significant effect on decline in eGFR events (RR: 0.34; 95% CI: 0.09-1.23), proteinuria (standardized mean difference: -0.32; 95% CI: -1.08 to 0.43), all-cause mortality events (RR: 0.90; 95% CI: 0.40-2.02) and cardiovascular (CV) events (RR: 1.03; 95% CI: 0.32-3.37) compared with the control groups.

CONCLUSION

Based on the available and low-to-moderate certainty evidence, oral alkali drug therapy might potentially reduce the risk of kidney failure events, but no benefit in reducing all-cause mortality events, CV events, decline in eGFR and porteninuria.

OUP accepted manuscript

Patients on chronic hemodialysis are counseled to reduce dietary sodium intake to limit their thirst and consequent interdialytic weight gain (IDWG), chronic volume overload and hypertension. Low-sodium dietary trials in hemodialysis are sparse and mostly indicate that dietary education and behavioral counseling are ineffective in reducing sodium intake and IDWG. Additional nutritional restrictions and numerous barriers further complicate dietary adherence. A low-sodium diet may also reduce tissue sodium, which is positively associated with hypertension and left ventricular hypertrophy. A potential alternative or complementary approach to dietary counseling is home delivery of low-sodium meals. Low-sodium meal delivery has demonstrated benefits in patients with hypertension and congestive heart failure but has not been explored or implemented in patients undergoing hemodialysis. The objective of this review is to summarize current strategies to improve volume overload and provide a rationale for low-sodium meal delivery as a novel method to reduce volume-dependent hypertension and tissue sodium accumulation while improving quality of life and other clinical outcomes in patients undergoing hemodialysis.

The Effects of Oral Sodium Bicarbonate on Renal Function and Cardiovascular Risk in Patients with Chronic Kidney Disease: A Systematic Review and Meta-Analysis

OBJECTIVE

Oral sodium bicarbonate is often used to correct acid-base disturbance in patients with chronic kidney disease (CKD). However, there is little evidence on patient-level benign outcomes to support the practice.

METHODS

We conducted a systematic review and meta-analysis to examine the efficacy and safety of oral sodium bicarbonate in CKD patients. A total of 1853 patients with chronic metabolic acidosis or those with low-normal serum bicarbonate (22-24 mEq/L) were performed to compare the efficacy and safety of oral sodium bicarbonate in patients with CKD.

RESULTS

There was a significant increase in serum bicarbonate level (MD 2.37 mEq/L; 95% CI, 1.03 to 3.72) and slowed the decline in estimated glomerular filtration rate (eGFR) (MD -4.44 mL/min per 1.73 m2, 95% CI, -4.92 to -3.96) compared with the control groups. The sodium bicarbonate lowered T50-time, an indicator of vascular calcification (MD -20.74 min; 95% CI, -49.55 to 8.08); however, there was no significant difference between the two groups. In addition, oral sodium bicarbonate dramatically reduced systolic blood pressure (MD -2.97 mmHg; 95% CI, -5.04 to -0.90) and diastolic blood pressure (MD -1.26 mmHg; 95% CI, -2.33 to -0.19). There were no statistically significant body weight, urine pH and mean mid-arm muscle circumference.

CONCLUSION

Treatment of metabolic acidosis with sodium bicarbonate may slow the decline rate of kidney function and potentially significantly improve vascular endothelial function in patients with CKD.

PROSPERO REGISTRATION NUMBER

CRD42020207185.

Fructose in the kidney: from physiology to pathology

The Warburg effect is a unique property of cancer cells, in which glycolysis is activated instead of mitochondrial respiration despite oxygen availability. However, recent studies found that the Warburg effect also mediates non-cancer disorders, including kidney disease. Currently, diabetes or glucose has been postulated to mediate the Warburg effect in the kidney, but it is of importance that the Warburg effect can be induced under nondiabetic conditions. Fructose is endogenously produced in several organs, including the kidney, under both physiological and pathological conditions. In the kidney, fructose is predominantly metabolized in the proximal tubules; under normal physiologic conditions, fructose is utilized as a substrate for gluconeogenesis and contributes to maintain systemic glucose concentration under starvation conditions. However, when present in excess, fructose likely becomes deleterious, possibly due in part to excessive uric acid, which is a by-product of fructose metabolism. A potential mechanism is that uric acid suppresses aconitase in the Krebs cycle and therefore reduces mitochondrial oxidation. Consequently, fructose favors glycolysis over mitochondrial respiration, a process that is similar to the Warburg effect in cancer cells. Activation of glycolysis also links to several side pathways, including the pentose phosphate pathway, hexosamine pathway, and lipid synthesis, to provide biosynthetic precursors as fuel for renal inflammation and fibrosis. We now hypothesize that fructose could be the mediator for the Warburg effect in the kidney and a potential mechanism for chronic kidney disease.

Lifestyle interventions for preventing and ameliorating CKD in primary and secondary care

PURPOSE OF REVIEW

Despite the growth in chronic kidney disease (CKD) epidemics, evidence-based lifestyle recommendations for primary prevention of CKD are limited by reliance on observational studies and predominantly pilot clinical trials.

RECENT FINDINGS

Emerging data have shown lifestyle modification strategies for primary CKD prevention with the most evidence favoring a healthy dietary pattern (rich in fruit, vegetables, potassium and have a higher plant-based to animal protein ratio), and diet low in sodium, being physically active, avoiding tobacco smoking, moderating alcohol consumption and maintaining a healthy body weight. The way these behavioral interventions can be implemented in practice should consider their synergistic benefit as well as mechanisms to facilitate long-term behavior change. Sustaining long-term behavior change remains a challenge in practice, particularly due to a lack of healthcare resources and behavior relapse. Some suggestions to mitigate this include ensuring adequate time is spent in intervention codesign and planning, utilizing adaptive trial/intervention designs with regular intervention tailoring for intervention dose, intensity, duration, and modality.

SUMMARY

A number of modifiable lifestyle behaviors consistently associate with developing CKD in the community. The current evidence base, despite its inherent limitations, may inform both public health recommendations and clinical practice.

Effect of Oral Sodium Bicarbonate Treatment on 24-Hour Ambulatory Blood Pressure Measurements in Patients With Chronic Kidney Disease and Metabolic Acidosis

Background: Sodium bicarbonate supplementation is a mainstay in the treatment of metabolic acidosis in patients with chronic kidney disease (CKD). Recent studies showed reduction of progression of CKD and reduced all-cause mortality. However, additional sodium loading could worsen arterial hypertension, a well-known contributor to progression of CKD. This patient-relevant and economically negative side effect is under-studied in prospective studies up until now.

Objective: The aim of this study was to analyze the effect of sodium bicarbonate treatment on arterial blood pressure at baseline and after 8 weeks.

Methods: The SoBic study is an ongoing randomized controlled trial, in which patients with CKD receive either a high dose of oral sodium bicarbonate or a rescue treatment, if necessary. We used standardized office blood pressure and 24-hour ambulatory blood pressure monitoring (24h-ABPM). Regression models were adjusted for estimated glomerular filtration rate and change of antihypertensives.

Results: 47 subjects were enrolled and the mean age was 57 (±14.6) years and 18 (38%) were female. In 43 randomized subjects with sufficiently performed 24h-ABPM neither systolic 24h-ABPM (2.522; 95%CI: −2.364, 7.408; mmHg) nor diastolic 24h-ABPM (0.868; 95%CI: −2.411, 4.147; mmHg) was affected by study group allocation. When looking at the effect of individual sodium bicarbonate dose on 24h-ABPM, the fully adjusted model suggested an increase of 0.047 (95%CI: −0.026, 0.119) mmHg by each mg/kg per day increase of sodium bicarbonate dose.

Conclusion: Sodium bicarbonate supplementation over 8 weeks did not significantly increase blood pressure measured by 24h-ABPM in CKD patients.

Trial Registration: EUDRACT Number: 2012-001824-36; 12/07/2012 (https://www.clinicaltrialsregister.eu).

Preventing potential pitfalls of a liberalized potassium diet in the hemodialysis population

Emerging research suggests that a more liberalized diet, specifically a more plant-based diet resulting in liberalization of potassium intake, for people receiving hemodialysis is necessary and the benefits outweigh previously thought risks. If the prescribed hemodialysis diet is to be liberalized, the need to illuminate and prevent potential pitfalls of a liberalized potassium diet is warranted. This paper explores such topics as partial to full adherence to a liberalized diet and its consequences if any, the advantages of a high-fiber intake, the theoretical risk of anemia when consuming a more plant-dominant diet, the potential benefits against renal acid load and effect on metabolic acidosis with increased fruit and vegetable intake, the putative change in serum potassium levels, carbohydrate quality, and the healthfulness of meat substitutes. The benefits of a more plant-based diet for the hemodialysis population are multifold; however, the possible pitfalls of this type of diet must be reviewed and addressed upon meal planning in order to be avoided.

Optimizing Diet to Slow CKD Progression

Due to the unique role of the kidney in the metabolism of nutrients, patients with chronic kidney disease (CKD) lose the ability to excrete solutes and maintain homeostasis. Nutrient intake modifications and monitoring of nutritional status in this population becomes critical, since it can affect important health outcomes, including progression to kidney failure, quality of life, morbidity, and mortality. Although there are multiple hemodynamic and metabolic factors involved in the progression and prognosis of CKD, nutritional interventions are a central component of the care of patients with non-dialysis CKD (ND-CKD) and of the prevention of overweight and possible protein energy-wasting. Here, we review the reno-protective effects of diet in adults with ND-CKD stages 3-5, including transplant patients.

Dietary Factors and Prevention: Risk of End-Stage Kidney Disease by Fruit and Vegetable Consumption

BACKGROUND

The association between fruit and vegetable (FV) intake and the risk of end-stage kidney disease (ESKD) has not been examined in the general population and fully explored in chronic kidney disease (CKD). We prospectively evaluated this relationship in US representative sample of adults and evaluated consistency by the presence or absence, and severity, of CKD.

METHODS

We used data from the Third National Health and Nutrition Examination Survey (1988-1994) linked with the US Renal Data System, including 14,725 adults aged ≥20 years and with follow-up for ESKD through 2008. Daily FV intake was ascertained using a food frequency questionnaire. We examined the association between selected categories of FV intake and ESKD using a Fine Gray competing risk model adjusting for sociodemographics, lifestyle, clinical and nutritional factors, estimated glomerular filtration rate, and albuminuria. We evaluated whether risk varied in individuals with severe versus any CKD.

RESULTS

230 participants (1.5%) developed ESKD during follow-up. In the adjusted model, compared to highest intake, those in lowest categories of FV intake had a higher risk of ESKD, for <2 times/day (1.45 [1.24-1.68], 2 to <3 times/day (1.40 [1.18-1.61]), 3 to <4 times/day (1.25 [1.04-1.46]), and 4 to <6 times/day (1.14 [0.97-1.31]). There was suggestion of heterogeneity (p for interaction = 0.03) with possible stronger inverse association in patients with CKD than those without CKD. After stratification, we obtained similar strong inverse association when we examined ESKD incidence across intake of FVs in participants with CKD stages 1-4 (n = 5,346) and specifically in those with CKD stages 3-4 (n = 1,084).

CONCLUSIONS

Low intake of FVs was associated with higher risk of ESKD in US adults with and without CKD, supporting an emerging body of literature on the potential benefits of plant-rich diets for prevention of ESKD.

Recent evidence on the effect of treatment of metabolic acid on the progression of kidney disease

PURPOSE OF REVIEW

Preclinical and epidemiological studies have shown an association between acidosis and progression of chronic kidney disease (CKD) and kidney fibrosis. This review discusses the recent trials evaluating the effect of treatment of metabolic acidosis on kidney outcomes.

RECENT FINDINGS

The emerging evidence suggests that bicarbonate treatment may slow the progression of CKD and reduce the risk of kidney failure. However, high-certainty evidence on the efficacy and safety of alkali therapy is still lacking. Ongoing studies are evaluating the effect of veverimer, a novel nonabsorbable polymer, on clinical kidney outcomes.

SUMMARY

Recent studies indicate a potential benefit from reduction in acid load in patients with CKD. Whilst it is reasonable that clinicians institute acid-lowering interventions in CKD patients with acidosis, adequately powered trials are required to evaluate the benefit of correction of metabolic acidosis to delay kidney disease progression.

Obesity and the Risk of Low Bicarbonate: A Cohort Study

Rationale & Objective

Acid retention may occur in the absence of overt metabolic acidosis; thus it is important to identify populations at risk. Because obesity may alter renal acid-base handling, we sought to determine whether overweight and obesity are associated with increased risk for low serum bicarbonate levels, suggesting metabolic acidosis.

Study Design

Retrospective cohort study.

Setting & Participants

Adult patients (n = 96,147) visiting outpatient clinics in the Bronx, NY, between January 1, 2010, and December 31, 2015.

Predictor

Body mass index (BMI).

Outcome

Low serum bicarbonate level (≤23 mEq/L).

Analytical Approach

Longitudinal analyses were conducted using mixed-effects models to examine associations of BMI with serum bicarbonate levels over time and Cox proportional hazards models to examine associations of BMI with incident low bicarbonate levels.

Results

During a median follow-up of 4.4 (interquartile range, 2.3-6.3) years, patients had a median of 8 serum bicarbonate measurements and 34,539 patients developed low bicarbonate levels. Higher BMI was associated with progressively lower serum bicarbonate levels, with attenuation of the association in the highest BMI groups, suggesting a J-shaped relationship. Compared with the reference group (BMI, 18.5 to <25 kg.m²), patients with BMIs of 25 to <30, 30 to <35, 35 to <40, and ≥40 kg/m² had HRs for incident low bicarbonate levels of 1.10 (95% CI, 1.05-1.14), 1.16 (95% CI, 1.11-1.21), 1.20 (95% CI, 1.14-1.26), and 1.15 (95% CI, 1.09-1.22). Results were similar after adjustment for serum urea nitrogen level and exclusion of patients with diabetes, hypertension, or estimated glomerular filtration rates < 60 mL/min/1.73 m².

Limitations

Arterial pH measurements were unavailable.

Conclusions

Higher BMI is independently associated with progressively greater risk for developing low serum bicarbonate levels, indicating likely metabolic acidosis. Further research should explore the causes of low bicarbonate levels in patients with overweight and obesity.

New insights into muscle function in chronic kidney disease and metabolic acidosis

PURPOSE OF REVIEW

: Sarcopenia, defined as decreased muscle mass or function, is prevalent in chronic kidney disease (CKD) increasing the risk of mobility impairment and frailty. CKD leads to metabolic acidosis (MA) and retention of uremic toxins contributing to insulin resistance and impaired muscle mitochondrial energetics. Here we focus on the central role of muscle mitochondrial metabolism in muscle function.

RECENT FINDINGS

: Mitochondrial dysfunction underlies muscle wasting and poor physical endurance in CKD. Uremic toxins accumulate in muscle disrupting mitochondrial respiration and enzymes. Changes in mitochondrial quantity, quality, and oxidative capacity contribute to mobility impairment in CKD. Major determinants of muscle mitochondrial function are kidney function, inflammation, and oxidative stress. In CKD, MA is the major determinant of muscle mitochondrial function. Metabolomics reveals defects in pathways linked to mitochondrial energy metabolism and acid-base homeostasis underlying insulin resistance in CKD.

SUMMARY

: Decreased mitochondrial capacity and quality control can impair muscle function contributing to decreased physical endurance. MA augments insulin resistance perpetuating the catabolic state underlying muscle wasting in CKD. Further studies are needed to investigate if targeting of MA improves muscle mitochondrial function and insulin resistance translating into meaningful improvements in physical endurance.

Dietary interventions with dietitian involvement in adults with chronic kidney disease: A systematic review

BACKGROUND

A comprehensive evidence base is needed to support recommendations for the dietetic management of adults with chronic kidney disease (CKD). The present study aimed to determine the effect of dietary interventions with dietitian involvement on nutritional status, well-being, kidney risk factors and clinical outcomes in adults with CKD.

METHODS

Cochrane Central Register of Controlled Trials, CINAHL, MEDLINE, PsycINFO and EMBASE.com were searched from January 2000 to November 2019. Intentional weight loss and single nutrient studies were excluded. Risk of bias was assessed using the Cochrane risk-of-bias tool. Effectiveness was summarised using the mean difference between groups for each outcome per study.

RESULTS

Twelve controlled trials (1906 participants) were included. High fruit and vegetable intake, as well as a multidisciplinary hospital and community care programme, slowed the decline in glomerular filtration rate in adults with stage 3-4 CKD. Interventions addressing nutrition-related barriers increased protein and energy intake in haemodialysis patients. A Mediterranean diet and a diet with high n-3 polyunsaturated fatty acids improved the lipid profile in kidney transplant recipients.

CONCLUSIONS

A limited number of studies suggest benefits as a result of dietary interventions that are delivered by dietitians and focus on diet quality. We did not identify any studies that focussed on our primary outcome of nutritional status or studies that examined the timing or frequency of the nutritional assessment. This review emphasises the need for a wider body of high-quality evidence to support recommendations on what and how dietetic interventions are delivered by dietitians for adults with CKD.

The therapeutic importance of acid-base balance

Baking soda and vinegar have been used as home remedies for generations and today we are only a mouse-click away from claims that baking soda, lemon juice, and apple cider vinegar are miracles cures for everything from cancer to COVID-19. Despite these specious claims, the therapeutic value of controlling acid-base balance is indisputable and is the basis of Food and Drug Administration-approved treatments for constipation, epilepsy, metabolic acidosis, and peptic ulcers. In this narrative review, we present evidence in support of the current and potential therapeutic value of countering local and systemic acid-base imbalances, several of which do in fact involve the administration of baking soda (sodium bicarbonate). Furthermore, we discuss the side effects of pharmaceuticals on acid-base balance as well as the influence of acid-base status on the pharmacokinetic properties of drugs. Our review considers all major organ systems as well as information relevant to several clinical specialties such as anesthesiology, infectious disease, oncology, dentistry, and surgery.

Effect of sodium bicarbonate supplementation on the renin-angiotensin system in patients with chronic kidney disease and acidosis: a randomized clinical trial

Background

Acidosis-induced kidney injury is mediated by the intrarenal renin-angiotensin system, for which urinary renin is a potential marker. Therefore, we hypothesized that sodium bicarbonate supplementation reduces urinary renin excretion in patients with chronic kidney disease (CKD) and metabolic acidosis.

Methods

Patients with CKD stage G4 and plasma bicarbonate 15–24 mmol/l were randomized to receive sodium bicarbonate (3 × 1000 mg/day, ~ 0.5 mEq/kg), sodium chloride (2 × 1,00 mg/day), or no treatment for 4 weeks (n = 15/arm). The effects on urinary renin excretion (primary outcome), other plasma and urine parameters of the renin-angiotensin system, endothelin-1, and proteinuria were analyzed.

Results

Forty-five patients were included (62 ± 15 years, eGFR 21 ± 5 ml/min/1.73m², plasma bicarbonate 21.7 ± 3.3 mmol/l). Sodium bicarbonate supplementation increased plasma bicarbonate (20.8 to 23.8 mmol/l) and reduced urinary ammonium excretion (15 to 8 mmol/day, both P < 0.05). Furthermore, a trend towards lower plasma aldosterone (291 to 204 ng/L, P = 0.07) and potassium (5.1 to 4.8 mmol/l, P = 0.06) was observed in patients receiving sodium bicarbonate. Sodium bicarbonate did not significantly change the urinary excretion of renin, angiotensinogen, aldosterone, endothelin-1, albumin, or α1-microglobulin. Sodium chloride supplementation reduced plasma renin (166 to 122 ng/L), and increased the urinary excretions of angiotensinogen, albumin, and α1-microglobulin (all P < 0.05).

Conclusions

Despite correction of acidosis and reduction in urinary ammonium excretion, sodium bicarbonate supplementation did not improve urinary markers of the renin-angiotensin system, endothelin-1, or proteinuria. Possible explanations include bicarbonate dose, short treatment time, or the inability of urinary renin to reflect intrarenal renin-angiotensin system activity.

Graphic abstract

A Systematic Review and Meta-Analysis on Effects of Bicarbonate Therapy on Kidney Outcomes

Aim

Preclinical studies suggest treatment of metabolic acidosis may slow chronic kidney disease (CKD) progression. This systematic review aimed to summarize evidence from randomized controlled trials (RCTs) concerning the benefits and risks of bicarbonate therapy on kidney outcomes.

Methods

Medline, EMBASE, and Cochrane databases were searched for RCTs with ≥3 months’ follow-up in patients with CKD (estimated glomerular filtration rate [eGFR] ≤60 ml/min per 1.73 m² and/or proteinuria) comparing the effects of sodium bicarbonate with placebo/no study medication on kidney outcomes. The primary outcome was change from baseline to last measurement in kidney function measured as either eGFR or creatinine clearance. Treatment effects were summarized using random-effects meta-analysis.

Results

Fifteen trials (2445 participants, median follow-up 12 months) were eligible for inclusion. Compared with placebo or no study medication, sodium bicarbonate retarded the decline in kidney function (standardized mean difference [SMD]: 0.26; 95% confidence interval [CI]: 0.13–0.40; I² = 50%, low certainty evidence), and reduced the risk of end-stage kidney failure (risk ratio [RR]: 0.53; 95% CI 0.32–0.89; I² = 69%, low certainty evidence). The effect of sodium bicarbonate on proteinuria (SMD: −0.09; 95% CI −0.27 to 0.09; I² = 28%, very low certainty evidence), systolic blood pressure (weighted mean difference [WMD]: −0.57 mm Hg; 95% CI −2.32 to 1.18; I² = 0%, low certainty evidence), all-cause death (RR: 0.81; 95% CI: 0.39–1.68; I² = 30%; very low certainty evidence) and edema (RR: 1.16; 95% CI: 0.90–1.50; I² = 28%; low certainty evidence) were uncertain.

Conclusion

Sodium bicarbonate may slow CKD progression. Adequately powered randomized trials are required to evaluate the benefits and risks of sodium bicarbonate in CKD.