High Dietary Acid Load Predicts ESRD among Adults with CKD

Effects of higher dietary acid load: a narrative review with special emphasis in children

Metabolic effects of high diet acid load (DAL) have been studied for years in adults, although only recently in children. Contemporary diets, especially those of Western societies, owe their acidogenic effect to high animal-origin protein content and low contribution of base-forming elements, such as fruits and vegetables. This imbalance, where dietary acid precursors exceed the body's buffering capacity, results in an acid-retaining state known by terms such as "eubicarbonatemic metabolic acidosis," "low-grade metabolic acidosis," "subclinical acidosis," or "acid stress". Its consequences have been linked to chronic systemic inflammation, contributing to various noncommunicable diseases traditionally considered more common in adulthood, but now have been recognized to originate at much earlier ages. In children, effects of high DAL are not limited to growth impairment caused by alterations of bone and muscle metabolism, but also represent a risk factor for conditions such as obesity, insulin resistance, diabetes, hypertension, urolithiasis, and chronic kidney disease (CKD). The possibility that high DAL may be a cause of chronic acid-retaining states in children with growth impairment should alert pediatricians and pediatric nephrologists, since its causes have been attributed traditionally to inborn errors of metabolism and renal pathologies such as CKD and renal tubular acidosis. The interplay between DAL, overall diet quality, and its cascading effects on children's health necessitates comprehensive nutritional assessments and interventions. This narrative review explores the clinical relevance of diet-induced acid retention in children and highlights the potential for prevention through dietary modifications, particularly by increasing fruit and vegetable intake alongside appropriate protein consumption.

Association between Dietary Acid Load and Chronic Kidney Disease in the Chinese Population: A Comprehensive Analysis of the China Health and Nutrition Survey (2009)

BACKGROUND

Dietary acid load (DAL) is closely related to several chronic diseases. However, the link between DAL and chronic kidney disease (CKD) remains scarce and without data from the Chinese populations whose diet is quite different from people in Western countries.

METHODS

This study evaluated DAL by potential renal acid load (PRAL) and net endogenous acid production (NEAP). We clarified the relationship between DAL and CKD by logistic regression analysis based on data from the China Health and Nutrition Survey (CHNS).

RESULTS

The final analysis included 7699 individuals, of whom 811 (11.44%) were CKD patients. Although there was no notable link between PRAL and CKD, higher NEAP levels were independently correlated with CKD. As NEAP values rise, so does CKD prevalence. This trend remains highly significant even after adjustments. In subgroup analyses, the relationship between NEAP and CKD was more consistent in the elderly and subjects with a waistline of less than 82 cm and those without diabetes and heart disease. RCS analysis further confirmed the clear linear relationship between the OR of CKD and NEAP score.

CONCLUSIONS

This study highlighted that higher NEAP was positively correlated with the risk of CKD.

Kidney and Cardiovascular Protection Using Dietary Acid Reduction in Primary Hypertension: A Five-Year, Interventional, Randomized, Control Trial

BACKGROUND

High fruit and vegetable diets are associated with reduced chronic kidney disease and cardiovascular disease but are infrequently used in hypertension treatment. Low acid diets are also associated with reduced chronic kidney disease and cardiovascular disease, and fruits and vegetables or oral sodium bicarbonate (NaHCO3) lowers dietary acid.

METHODS

We randomized 153 hypertensive macroalbuminuric patients receiving pharmacologic chronic kidney disease and cardiovascular disease protection to get fruits and vegetables, oral NaHCO3, or Usual Care. We assessed the course of kidney disease progression and cardiovascular disease risk indices over five years.

RESULTS

Chronic kidney disease progression was slower in participants receiving fruits and vegetables or oral NaHCO3 than Usual Care [mean (SE)] [-1.08 (0.06) and -1.17 (0.07) vs. -1.94 (0.11) mL/min/1.73m2/ year, respectively, P's< .001). Yet, systolic blood pressure was lower, and cardiovascular disease risk indices improved more in participants receiving fruits and vegetables than in those receiving NaHCO3 or Usual Care. These cardiovascular benefits of fruits and vegetables were achieved despite lower doses of pharmacologic chronic kidney disease and cardiovascular disease protection.

CONCLUSION

The trial supports fruits and vegetables as foundational hypertension treatment to reduce chronic kidney disease progression and cardiovascular disease risk.

Metabolomic and Physiological Effects of a Cardiorenal Protective Diet Intervention in African American Adults with Chronic Kidney Disease

Chronic kidney disease (CKD) impacts 14% of adults in the United States, and African American (AA) individuals are disproportionately affected, with more than 3 times higher risk of kidney failure as compared to White individuals. This study evaluated the effects of base-producing fruit and vegetables (FVs) on cardiorenal outcomes in AA persons with CKD and hypertension (HTN) in a low socioeconomic area. The "Cardiorenal Protective Diet" prospective randomized trial evaluated the effects of a 6-week, community-based FV intervention compared to a waitlist control (WL) in 91 AA adults (age = 58.3 ± 10.1 years, 66% female, 48% income ≤ USD 25K). Biometric and metabolomic variables were collected at baseline and 6 weeks post-intervention. The change in health outcomes for both groups was statistically insignificant (p > 0.05), though small reductions in albumin to creatinine ratio, body mass index, total cholesterol, and systolic blood pressure were observed in the FV group. Metabolomic profiling identified key markers (p < 0.05), including C3, C5, 1-Met-His, kynurenine, PC ae 38:5, and choline, indicating kidney function decline in the WL group. Overall, delivering a directed cardiorenal protective diet intervention improved cardiorenal outcomes in AA adults with CKD and HTN. Additionally, metabolomic profiling may serve as a prognostic technique for the early identification of biomarkers as indicators for worsening CKD and increased CVD risk.

Metabolic Acidosis in CKD: Pathogenesis, Adverse Effects, and Treatment Effects

Metabolic acidosis is a frequent complication of chronic kidney disease and is associated with a number of adverse outcomes, including worsening kidney function, poor musculoskeletal health, cardiovascular events, and death. Mechanisms that prevent metabolic acidosis detrimentally promote further kidney damage, creating a cycle between acid accumulation and acid-mediated kidney injury. Disrupting this cycle through the provision of alkali, most commonly using sodium bicarbonate, is hypothesized to preserve kidney function while also mitigating adverse effects of excess acid on bone and muscle. However, results from clinical trials have been conflicting. There is also significant interest to determine whether sodium bicarbonate might improve patient outcomes for those who do not have overt metabolic acidosis. Such individuals are hypothesized to be experiencing acid-mediated organ damage despite having a normal serum bicarbonate concentration, a state often referred to as subclinical metabolic acidosis. Results from small- to medium-sized trials in individuals with subclinical metabolic acidosis have also been inconclusive. Well-powered clinical trials to determine the efficacy and safety of sodium bicarbonate are necessary to determine if this intervention improves patient outcomes.

Dietary acid load in health and disease

Maintaining an appropriate acid-base equilibrium is crucial for human health. A primary influencer of this equilibrium is diet, as foods are metabolized into non-volatile acids or bases. Dietary acid load (DAL) is a measure of the acid load derived from diet, taking into account both the potential renal acid load (PRAL) from food components like protein, potassium, phosphorus, calcium, and magnesium, and the organic acids from foods, which are metabolized to bicarbonate and thus have an alkalinizing effect. Current Western diets are characterized by a high DAL, due to large amounts of animal protein and processed foods. A chronic low-grade metabolic acidosis can occur following a Western diet and is associated with increased morbidity and mortality. Nutritional advice focusing on DAL, rather than macronutrients, is gaining rapid attention as it provides a more holistic approach to managing health. However, current evidence for the role of DAL is mainly associative, and underlying mechanisms are poorly understood. This review focusses on the role of DAL in multiple conditions such as obesity, cardiovascular health, impaired kidney function, and cancer.

Clinical practice guidelines for nutritional assessment and monitoring of adult ICU patients in China

The Chinese Society of Critical Care Medicine (CSCCM) has developed clinical practice guidelines for nutrition assessment and monitoring for patients in adult intensive care units (ICUs) in China. This guideline focuses on nutrition evaluation and metabolic monitoring to achieve optimal and personalized nutrition therapy for critically ill patients. This guideline was developed by experts in critical care medicine and evidence-based medicine methodology and was developed after a thorough review of the system and a summary of relevant trials or studies published from 2000 to July 2023. A total of 18 recommendations were formed and consensus was reached through discussions and reviews by expert groups in critical care medicine, parenteral and enteral nutrition, and surgery. The recommendations are based on currently available evidence and cover several key fields, including screening and assessment, evaluation and assessment of enteral feeding intolerance, metabolic and nutritional measurement and monitoring during nutrition therapy, and organ function evaluation related to nutrition supply. Each question was analyzed according to the Population, Intervention, Comparison, and Outcome (PICO) principle. In addition, interpretations were provided for four questions that did not reach a consensus but may have potential clinical and research value. The plan is to update this nutrition assessment and monitoring guideline using the international guideline update method within 3-5 years.

Metabolic acidosis in chronic kidney disease: mere consequence or also culprit?

Metabolic acidosis is a frequent complication in non-transplant chronic kidney disease (CKD) and after kidney transplantation. It occurs when net endogenous acid production exceeds net acid excretion. While nephron loss with reduced ammoniagenesis is the main cause of acid retention in non-transplant CKD patients, additional pathophysiological mechanisms are likely inflicted in kidney transplant recipients. Functional tubular damage by calcineurin inhibitors seems to play a key role causing renal tubular acidosis. Notably, experimental and clinical studies over the past decades have provided evidence that metabolic acidosis may not only be a consequence of CKD but also a driver of disease. In metabolic acidosis, activation of hormonal systems and the complement system resulting in fibrosis have been described. Further studies of changes in renal metabolism will likely contribute to a deeper understanding of the pathophysiology of metabolic acidosis in CKD. While alkali supplementation in case of reduced serum bicarbonate < 22 mmol/l has been endorsed by CKD guidelines for many years to slow renal functional decline, among other considerations, beneficial effects and thresholds for treatment have lately been under intense debate. This review article discusses this topic in light of the most recent results of trials assessing the efficacy of dietary and pharmacological interventions in CKD and kidney transplant patients.

Effects of Reduced Dietary Sodium and the DASH Diet on GFR: The DASH-Sodium Trial

Key Points

Sodium reduction over a 4-week period decreased eGFR. Combining sodium reduction with the Dietary Approaches to Stop Hypertension diet resulted in larger reductions in eGFR. Changes in diastolic BP seem partially responsible for the observed dietary effects.

Background

A potassium-rich Dietary Approaches to Stop Hypertension (DASH) diet combined with low sodium reduces BP. However, the effects of sodium reduction in combination with the DASH diet on kidney function are unknown. We determined the effects of sodium reduction and the DASH diet, on eGFR using cystatin C.

Methods

DASH-sodium was a controlled, feeding study in adults with elevated or stage 1 hypertension, randomly assigned to the DASH or a control diet. On their assigned diet, participants consumed each of three sodium levels for 30 days after a 2-week run-in period of a high sodium-control diet. The three sodium levels were low (50 mmol/d), medium (100 mmol/d), and high (150 mmol/d). The primary outcome was change in eGFR based on cystatin C.

Results

Cystatin C was measured in 409 of the original 412 participants, of which 207 were assigned the DASH diet and 202 to the control diet. Compared with control, the DASH diet did not affect eGFR (β =−0.96 ml/min per 1.73 m2; 95% confidence interval [CI], −2.74 to 0.83). By contrast, low versus high sodium intake decreased eGFR (β =−2.36 ml/min per 1.73 m2; 95% CI, −3.64 to −1.07). Together, compared with the high sodium-control diet, the low sodium-DASH diet decreased eGFR by 3.10 ml/min per 1.73 m2 (95% CI, −5.46 to −0.73). This effect was attenuated with adjustment for diastolic BP and 24-hour urinary potassium excretion.

Conclusions

A combined low sodium-DASH diet reduced eGFR over a 4-week period. Future research should focus on the effect of these dietary interventions on subclinical kidney injury and their long-term effect on progression to CKD.

Clinical Trial registration number

ClinicalTrials.gov, NCT00000608 .

Association between adequate dietary protein and all-cause and cardiovascular mortality in patients with selective glomerular hypofiltration syndrome

Aims: To determine the impact of dietary protein intake and protein sources on all-cause and cardiovascular mortality of selective glomerular hypofiltration syndrome (SGHS) patients. Methods: This study recruited participants from the National Health and Nutrition Examination Survey (NHANES) conducted between 1999 and 2004. Cox proportional hazard models and competing risk models were employed to investigate the effects of dietary protein intake and protein sources on all-cause and cardiovascular mortality in SGHS patients. Additionally, Cox regression models utilizing restricted cubic splines (RCS) were used to explore potential non-linear associations. Results: Over a median follow-up period of 204 months, 20.71% (449/2168) participants died, with 5.40% (117/2168) experiencing cardiovascular mortality. In the fully adjusted model, participants with the highest dietary protein intake (Q4, ≥107.13 g d-1) exhibited a 40% reduced risk of all-cause mortality (HR: 0.60, 95% CI: 0.39 to 0.94) and an 88% reduced risk of cardiovascular mortality (HR: 0.12, 95% CI: 0.04 to 0.35) compared to those with the lowest dietary protein intake (Q1, < 57.93 g d-1). Notably, non-red meat protein sources were found to reduce the risk of all-cause and cardiovascular mortality, whereas no significant association was observed with red meat consumption. Conclusion: Adequate dietary protein intake has been linked to a decreased risk of all-cause and cardiovascular mortality in individuals with selective glomerular hypofiltration syndromes. This protective effect seems to be primarily associated with protein obtained from non-red meat sources.

The impact of ketogenic diet on some metabolic and non-metabolic diseases: Evidence from human and animal model experiments

The ketogenic diet (KD) is recognized as minimum carbohydrate and maximum fat intakes, which leads to ketosis stimulation, a state that is thought to metabolize fat more than carbohydrates for energy supply. KD has gained more interest in recent years and is for many purposes, including weight loss and managing serious diseases like type 2 diabetes. On the other hand, many believe that KD has safety issues and are uncertain about the health drawbacks. Thus, the outcomes of the effect of KD on metabolic and non-metabolic disease remain disputable. The current narrative review aims to evaluate the effect of KD on several diseases concerning the human health. To our best knowledge, the first report aims to investigate the efficacy of KD on multiple human health issues including type 2 diabetes and weight loss, cardiovascular disease, kidney failure and hypertension, non-alcoholic fatty liver, mental problem, oral health, libido, and osteoporosis. The literature searches were performed in Databases, PubMed, Scopus, and web of Science looking for both animal and human model designs. The results heterogeneity seems to be explained by differences in diet composition and duration. Also, the available findings may show that proper control of carbohydrates, a significant reduction in glycemic control and glycated hemoglobin, and weight loss by KD can be an approach to improve diabetes and obesity, hypertension, non-alcoholic fatty liver, PCOS, libido, oral health, and mental problem if isocaloric is considered. However, for some other diseases like cardiovascular disease and osteoporosis, more robust data are needed. Therefore, there is robust data to support the notion that KD can be effective for some metabolic and non-metabolic diseases but not for all of them. So they have to be followed cautiously and under the supervision of health professionals.

Paving a Path to Equity in Cardiorenal Care

Cardiorenal syndrome encompasses a dynamic interplay between cardiovascular and kidney disease, and its prevention requires careful examination of multiple predisposing underlying conditions. The unequal distribution of diabetes, heart failure, hypertension, and kidney disease requires special attention because of the influence of these conditions on cardiorenal disease. Despite growing evidence regarding the benefits of disease-modifying agents (e.g., sodium-glucose cotransporter 2 inhibitors) for cardiovascular, kidney, and metabolic (CKM) disease, significant disparities remain in access to and utilization of these essential therapeutics. Multilevel barriers impeding their use require multisector interventions that address patient, provider, and health system-tailored strategies. Burgeoning literature also describes the critical role of unequal social determinants of health, or the sociopolitical contexts in which people live and work, in cardiorenal risk factors, including heart failure, diabetes, and chronic kidney disease. This review outlines (i) inequality in the burden and treatment of hypertension, type 2 diabetes, and heart failure; (ii) disparities in the use of key disease-modifying therapies for CKM diseases; and (iii) multilevel barriers and solutions to achieve greater pharmacoequity in the use of disease-modifying therapies. In addition, this review provides summative evidence regarding the role of unequal social determinants of health in cardiorenal health disparities, further outlining potential considerations for future research and intervention. As proposed in the 2023 American Heart Association presidential advisory on CKM health, a paradigm shift will be needed to achieve cardiorenal health equity. Through a deeper understanding of CKM health and a commitment to equity in the prevention, detection, and treatment of CKM disease, we can achieve this critical goal.

Pathophysiology of Diet-Induced Acid Stress

Diets can influence the body's acid-base status because specific food components yield acids, bases, or neither when metabolized. Animal-sourced foods yield acids and plant-sourced food, particularly fruits and vegetables, generally yield bases when metabolized. Modern diets proportionately contain more animal-sourced than plant-sourced foods, are, thereby, generally net acid-producing, and so constitute an ongoing acid challenge. Acid accumulation severe enough to reduce serum bicarbonate concentration, i.e., manifesting as chronic metabolic acidosis, the most extreme end of the continuum of "acid stress", harms bones and muscles and appears to enhance the progression of chronic kidney disease (CKD). Progressive acid accumulation that does not achieve the threshold amount necessary to cause chronic metabolic acidosis also appears to have deleterious effects. Specifically, identifiable acid retention without reduced serum bicarbonate concentration, which, in this review, we will call "covert acidosis", appears to cause kidney injury and exacerbate CKD progression. Furthermore, the chronic engagement of mechanisms to mitigate the ongoing acid challenge of modern diets also appears to threaten health, including kidney health. This review describes the full continuum of "acid stress" to which modern diets contribute and the mechanisms by which acid stress challenges health. Ongoing research will develop clinically useful tools to identify stages of acid stress earlier than metabolic acidosis and determine if dietary acid reduction lowers or eliminates the threats to health that these diets appear to cause.

Elevated Inflammation and Poor Diet Quality Associated with Lower eGFR in United States Adults: An NHANES 2015-2018 Analysis

Chronic kidney disease is prevalent within the United States likely due to dietary habits. The purpose of this study was to examine the relationship between the high-sensitivity c-reactive protein (hs-CRP) and diet quality (DQ) and their effect on the eGFR. A cross-sectional secondary data analysis study was conducted among adults (n = 6230) using NHANES 2015-2018 data. DQ was determined by the Healthy Eating Index-2015 (HEI-2015). Multivariable linear regressions were conducted based on eGFR (≥90 or <60 mL/min/1.73 m2) after adjustments for age, race/ethnicity, hypertension, diabetes mellitus, cardiovascular disease, and kidney disease awareness. All analyses were performed in SAS version 9.4 with a statistical significance of p < 0.05. Results showed that participants who had an eGFR of <60 mL/min/1.73 m2 were older and had a higher prevalence of hypertension and diabetes and had higher hs-CRP compared to participants with an eGFR ≥ 90 (p < 0.005). Of participants with an eGFR < 60, 27% reported that they were aware they had kidney disease. Regardless of the eGFR at baseline, there was a negative interaction effect on the DQ scores and hs-CRP on the eGFR (p < 0.05). Independently, for participants with an eGFR < 60, their DQ scores had a positive significant relationship on their eGFR (p = 0.03), whereas their hs-CRP had a negative significant relationship on thier eGFR (p < 0.001). For participants with an eGFR < 60, age, hypertension, and kidney disease awareness influenced this relationship (p < 0.001). Overall, low DQ and elevated hs-CRP contributed to a reduction in kidney function. Efforts to improve dietary intake and strategies to reduce inflammation and improve kidney function are necessary.

Dietary acid load and the risk of events of mortality and kidney replacement therapy in people with chronic kidney disease: the Progredir Cohort Study

BACKGROUND/OBJECTIVES

The association between dietary acid load (DAL) and chronic kidney disease (CKD) progression remains controversial. Also, there is a gap in the literature on the association between DAL and mortality. In this study, we evaluated the association between NEAP (net endogenous acid production) and PRAL (potential renal acid load) and the risk of events of all-cause mortality and kidney replacement therapy (KRT) in people with CKD.

SUBJECTS/METHODS

We included 442 patients (250 diabetics) from the Progredir Cohort Study, based in São Paulo, Brazil. We estimated NEAP and PRAL from dietary intake. Events of death before KRT and KRT were ascertained after a median follow-up of 5.8 and 5.1 years, respectively. Cox proportional hazards regression, Weibull regression, and competing risk models were performed.

RESULTS

Median NEAP and PRAL were 49.5 and 4.8 mEq/d. There were 200 deaths and 75 KRT events. Neither NEAP nor PRAL were associated with mortality or KRT when all participants were analyzed. After stratification for diabetes, both estimates were positively related to the risk of KRT even after adjustment for age, sex, weight status, glomerular filtration rate, serum bicarbonate, and intakes of protein, phosphorus, and energy (HR 1.31; 95% CI 1.07, 1.60 for NEAP, and HR 1.27; 95% CI 1.04, 1.57 for every 10 mEq/d increments). Competing risk analyses confirmed these findings.

CONCLUSIONS

DAL estimates were associated with the risk of KRT in people with CKD and diabetes but not in non-diabetics. There was no association between all-cause mortality and DAL.

Assessment of Dietary Acid Load in Children with Chronic Kidney Disease: An Observational Study

Introduction

Dietary acid load (DAL), which reflects the balance between acid- and alkaline-forming foods, is a modifiable risk factor for metabolic acidosis in CKD. Owing to the paucity of data in the Indian context, we undertook this cross-sectional study to estimate DAL and assess acid and alkaline food consumption in children with CKD2-5D (Chronic kidney disease stage 2 to 5 and 5D-those on hemodialysis).

Methods

Clinical profile, dietary assessment of energy, protein intake/deficits, and macronutrients were noted and computed using software created by the division of nutrition, St John's research institute based on Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines in clinically stable children with CKD2-5D. DAL was estimated using potential renal acid load (PRAL in mEq/day) = (0.49 × protein intake in g/day) + (0.037 × phosphorus-intake in mg/day) - (0.02 × potassium intake in mg/day) - (0.013 × calcium intake in mg/day) - (0.027 × magnesium intake in mg/day). A positive dietary PRAL (>0) favors acidic content and negative (<0) favors alkaline content. PRAL was stratified into quartiles for analysis. The association of various clinical and dietary parameters were analysed across these quartiles.

Results

Eighty-one children [of mean age 122 ± 47 months; 56 (69%) boys, 29 (36%) on dialysis, 62 (77%) non-vegetarians] were studied. Twenty-eight (34%) were on bicarbonate supplements. A positive PRAL (9.97 ± 7.7 mEq/day) was observed in 74/81 (91%) children with comparable proportions in those with CKD2-5 and 5D [47/52 (90%) vs. 27/29 (93%) respectively, P > 0.05]. Protein intake was significantly higher in the highest quartile compared to the lowest quartile of PRAL in CKD2-5 (55 ± 16 g/day vs. 40 ± 14 g/day, P < 0.001) and 5D groups (47 ± 15 g/day vs. 25 ± 11 g/day, P = 0.002). A majority of the participants 60/81 (74%) consumed highly acidic and minimal alkali foods.

Conclusion

In children with CKD2-5D, PRAL estimation revealed high DAL in the majority with a high consumption of acidic foods. These findings provide implications for appropriate dietary counseling in children with CKD.

Association of Higher Intake of Plant-Based Foods and Protein With Slower Kidney Function Decline in Women With HIV

BACKGROUND

We investigated whether there exists an association between dietary acid load and kidney function decline in women living with HIV (WLWH) receiving antiretroviral therapy (ART).

SETTING

One thousand six hundred eight WLWH receiving ART in the WIHS cohort with available diet data and a baseline estimated glomerular filtration rate (eGFR) ≥15 mL/minute/1.73 m2.

METHODS

A brief dietary instrument conducted from 2013 to 2016 under the Food Insecurity Sub-Study was used for assessing fruits and vegetables (FV) and protein intake. A mixed-effects model with random intercept and slope was used to estimate subjects' annual decline rate in eGFR and the association between FV intake and eGFR decline, adjusting for sociodemographics, serum albumin, comorbidities, time on ART, ART drugs, HIV markers, and baseline eGFR. We evaluated whether markers of inflammation mediated the effect of FV intake on decline in eGFR, using causal mediation analysis.

RESULTS

We found a dose-response relationship for the association of FV intake and eGFR decline, with lesser annual decline in eGFR in the middle and highest tertiles of FV intake. An increase of 5 servings of FV intake per day was associated with a lower annual eGFR decline (-1.18 [-1.43, -0.94]). On average, 39% of the association between higher FV intake and slower eGFR decline was explained by decreased levels of inflammation.

CONCLUSIONS

Plant-rich diet was associated with slower decline in kidney function. Inflammation is a potential path through which diet may affect kidney function. The findings support an emerging body of literature on the potential benefits of plant-rich diets for prevention of chronic kidney disease.

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.

Dietary acid load in children with chronic kidney disease: its association with nutritional status and health-related quality of life

BACKGROUND

This study aimed to determine the dietary acid load of children with chronic kidney disease (CKD) and to evaluate the relationship between dietary acid load, nutritional status, and health-related quality of life (HRQOL).

METHOD

A total of 67 children aged 3-18 years with a diagnosis of CKD stages II-V were included in the study. Anthropometric measurements (body weight, height, mid-upper arm circumference, waist, and neck circumference) and 3-day food consumption records were taken to evaluate the nutritional status. The net endogenous acid production (NEAP) score was calculated to determine the dietary acid load. "Pediatric Inventory of Quality of Life (PedsQL)" was used to assess the participants' HRQOL.

RESULTS

The mean NEAP was 59.2 ± 18.96 mEq/day. Stunted and malnourished children had significantly higher NEAP than those who were not (p < 0.05). There were no significant differences in terms of HRQOL scores according to NEAP groups. The multivariate logistic regression analysis showed that waist circumference (OR: 0.890, 95% CI: 0.794-0.997), serum albumin (OR: 0.252, 95% CI: 0.068-0.929), and glomerular filtration rate (GFR) (OR: 0.985, 95% CI: 0.970-1.000) were negatively associated with high NEAP.

CONCLUSION

This study shows that a diet shifted in an acidic direction in children with CKD and a higher dietary acid load are associated with lower serum albumin, GFR, and waist circumference, but not HRQOL. These results suggest that dietary acid load might affect nutritional status and CKD progression in children with CKD. Future studies with larger samples are needed to confirm these results and to understand underlying mechanisms. A higher resolution version of the Graphical abstract is available as Supplementary information.

Diet Quality and Kidney Outcomes in Adolescent and Adult American Indians: the Strong Heart Family Study

BACKGROUND

The burden of kidney disease is exceedingly high among American Indians (AIs). We sought to examine the relationship of diet quality, a modifiable risk factor, and kidney outcomes in AI adolescents and adults, hypothesizing that healthier diets are associated with lower odds of incident albuminuria and eGFR decline.

METHODS

This is an analysis from the Strong Heart Family Study, a longitudinal study of cardiovascular disease and its risk factors among AIs from Arizona, North and South Dakota, and Oklahoma (n = 1720, mean age 39 + / - 16 years, 16% adolescents at baseline). Participants completed two exams (baseline: 2001-2003; follow-up: 2007-2009). The primary exposure was diet quality, expressed as the Alternative Healthy Eating Index 2010 (AHEI), on a 110-point scale (assessed using a 119-item Block food frequency questionnaire). The primary outcomes were as follows: 1) incident albuminuria (albumin to creatinine ratio 30 mg/g or greater); and 2) eGFR decline of 30% or greater. Generalized estimating equations were used to examine the association of AHEI (in quartiles) with outcomes.

RESULTS

Ten percent of participants (6% of adolescents) had incident albuminuria and 2% of participants (2% of adolescents) had eGFR decline. For those with normal fasting glucose levels, the odds ratio (OR) for incident albuminuria comparing extreme quartiles of diet quality (least healthy [reference] versus healthiest quartiles) was 0.48 (95% CI 0.28, 0.81) after adjustment for demographics and comorbidities.

CONCLUSIONS

For American Indians with normal fasting glucose, higher diet quality decreases the odds of developing albuminuria. These findings inform future efforts to prevent CKD in American Indian adolescents and young adults.

High Alternative Health Eating Index-Taiwan Scores Are Associated With Prevention of Graft Dysfunction in Taiwanese Renal Transplant Recipients

BACKGROUND

Various dietary quality indices demonstrate that a higher dietary quality score is associated with a reduced risk of several chronic diseases. However, creating an index tailored to the national population is crucial. The study investigated the association between the Alternative Healthy Eating Index-Taiwan (AHEI-Taiwan) and graft dysfunction in Taiwanese renal transplant recipients (RTRs).

METHODS

A prospective cohort study recruited 102 RTRs with a functioning allograft without acute rejection in the last 3 months from September 2016 to June 2018. Laboratory data were obtained from the medical records of patients. Graft dysfunction was indicated by an estimated glomerular filtration rate (eGFR) <60 mL/min per 1.73 m² in accordance with the Kidney Disease Outcomes Quality Initiative guideline. The dietary quality index AHEI-Taiwan was adapted from the AHEI based on Taiwanese dietary recommendations.

RESULTS

Mean age, renal transplant time, and eGFR were 48.9 ± 12.8 years, 8.5 ± 5.8 years, and 54.9 ± 17.8 mL/min per 1.73 m², respectively, in 102 RTRs. The RTRs with the highest quartile of AHEI-Taiwan scores were older and had a higher eGFR. Logistic regression analysis adjusted for age, sex, calories, Charlson comorbidity index, transplant time, and dialysis time showed that the highest quartile of the AHEI-Taiwan was associated with an 88% (odds ratio, 0.12; 95% CI, 0.03-0.59, P < .01) lower risk of graft dysfunction.

CONCLUSION

A high AHEI-Taiwan score was associated with a reduced risk of graft dysfunction in Taiwanese RTRs.

Diet and Metabolism in CKD-Related Metabolic Acidosis

Metabolic acidosis is a common complication in patients with chronic kidney disease that occurs when the daily nonvolatile acid load produced in metabolism cannot be excreted fully by the kidney. A reduction in urine net acid excretion coupled with a high nonvolatile acid load may play a role in its pathogenesis. Diet is important in generation of the nonvolatile acid load. Acids are produced from metabolism of dietary protein and from the endogenous production of organic anions from neutral precursors. Acids can be balanced by alkali precursors ingested in the diet in the form of combustible organic anions. These typically are reflected indirectly by the excess of mineral cations to mineral anions in a food or diet. These principles underscore widely used methods to estimate the nonvolatile acid load from dietary intake using formulas such as the net endogenous acid production equation and the potential renal acid load equation. Empiric data largely validate these paradigms with high net endogenous acid production and potential renal acid load contributed by foods such as protein, grains, and dairy, and low net endogenous acid production and potential renal acid load contributed by fruits and vegetables along with corresponding dietary patterns. Although further studies are needed to understand the health benefits of altering nonvolatile acid load via diet, this review provides a detailed assessment on our current understanding of the role of diet in chronic kidney disease-related acidosis, providing an updated resource for researchers and clinicians.

Patient Perception of Plant Based Diets for Kidney Disease

OBJECTIVE

Plant-based diets can delay the progression of chronic kidney disease (CKD) and help manage complications and comorbid conditions such as hypertension, acidosis, diabetes, and cardiovascular disease. The objective of this study was to understand nephrology patients' familiarity, perception, and use of plant-based diets.

DESIGN & METHODS

A survey was shared via the National Kidney Foundation's social media channels. Analysis included 844 responses. Survey items were evaluated with descriptive statistics. Differences across items were determined using chi-square tests.

RESULTS

Most respondents were 61-70 years of age (26.7%, n = 225), female (56.5%, n = 477) and achieved a Bachelor's or advanced degree (49.9%, n = 421). The majority of respondents suffered from nondialysis-dependent CKD (34%) or received a kidney transplant (34%). About half (45%) of respondents were familiar with plant-based diets and most (58%) were aware that plant-based diets can improve CKD. Twenty-two percent reported following some version of a vegetarian diet, and 29% reported "eating less meat". Respondents were not confident (Mdn = 2, IQR = 2, on a scale of 1-5) in their ability to plan a balanced plant-based meal, and were moderately confident that a plant-based diet could help blood pressure (Mdn = 3, IQR = 2) and slow progression of CKD (Mdn = 3, IGR = 2). Family eating preference, meal planning skills, preference for meat, figuring out what is healthy to eat, food cost, time constraints, and ease of cooking were rated as equal barriers to following a plant-based diet (Mdn = 3). A sample meal plan, individual counseling session with a Registered Dietitian Nutritionist (RDN), handouts, and cooking classes were resources rated most helpful to transition to a plant-based diet (Mdn = 4).

CONCLUSION

Approximately half of respondents were aware that plant-based diets can be beneficial for CKD. Many patients are following a vegetarian or plant-based eating pattern. More research should be done to see how effective RDNs are in educating and moving patients toward a plant-based eating pattern, as they are an underutilized resource in the CKD population.

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.

Primary Contributors to Dietary Acid Load in Patients With Urolithiasis

OBJECTIVES

In susceptible individuals, high dietary acid load may contribute to the formation of certain types of kidney stones via lowering urine pH and citrate excretion. The objective of this study is to determine the contribution of dietary acid from food groups in people with urolithiasis.

DESIGN AND METHODS

Patients with calcium urolithiasis (n = 83) who completed food records were used for this retrospective analysis. Descriptive statistics were calculated for nutrients, potential renal acid load (PRAL), and estimated net endogenous acid production (NEAP_est). Pearson's correlations were calculated between PRAL and NEAP_est with each nutrient.

RESULTS

Data from a total of 83 patients were used. Average PRAL was positively correlated with energy (r = 0.260, P = .02), total protein (r = 0.463, P < .001), animal protein (r = 0.555, P < .001), total fat (P = .399, P < .001), sodium (r = 0.385, P < .001), and phosphorus (r = 0.345, P < .001) intake. PRAL was negatively correlated with fiber (r = -0.246, P = .03) intake. NEAP_est was positively correlated with total protein (r = 0.269, P = .01), animal protein (r = 0.377, P < .001), fat (r = 0.222, P = .04), and sodium (r = 0.250, P = .02) intake. NEAP_est was negatively correlated with fiber (r = -0.399, P < .001), potassium (r = -0.360, P < .001), and magnesium (r = -0.233, P = .03) intake. For PRAL, meat contributed the highest acid load (52.7%), followed by grains (19.6%) and combination foods (19.6%). Beverages contributed the greatest alkali load (35.1%), followed by vegetables (30.6%) and fruits (28.6%). For NEAP_est, cheese contributed the highest acid load (21.8%), followed by grains (19.3%) and meat (18.1%).

CONCLUSIONS

For individuals with urolithiasis promoted by acidic urine and/or low urine citrate, dietary patterns with a high dietary acid load may contribute to recurrence risk. Meat and grains were the major contributors to dietary acid load in this cohort of patients with a history of kidney stones, whereas beverages, fruits, and vegetables contributed net alkali.

Chronic Sub-Clinical Systemic Metabolic Acidosis - A Review with Implications for Clinical Practice

When arterial serum pH remains near the lower pH limit of 7.35 for protracted periods of time, a low-grade, sub-clinical form of acidosis results, referred to in this review as chronic, sub-clinical, systemic metabolic acidosis (CSSMA). This narrative review explores the scientific basis for CSSMA, its consequences for health, and potential therapeutic interventions. The major etiology of CSSMA is the shift away from the ancestral, alkaline diet which was rich in fruit and vegetables, toward the contemporary, acidogenic 'Westernized' diet characterized by higher animal protein consumption and lack of base forming minerals. Urine pH is reduced with high dietary acid load and may be a convenient marker of CSSMA. Evidence suggests further that CSSMA negatively influences cortisol levels potentially contributing significantly to the pathophysiology thereof. Both CSSMA and high dietary acid load are associated with the risk and prognosis of various chronic diseases. Clinical trials show that CSSMA can be addressed successfully through alkalizing the diet by increasing fruit and vegetable intake and/or supplementing with alkaline minerals. This review confirms the existence of a significant body of evidence regarding this low-grade form of acidosis as well as evidence to support its diverse negative implications for health, and concludes that CSSMA is a condition warranting further research.

Dietary Acid Load Was Positively Associated with the Risk of Hip Fracture in Elderly Adults

Previous studies have shown that dietary acid load (DAL) harms bone health, but the evidence is inconsistent and insufficient. This study examined the relationships between DAL and the risk of hip fracture. This case−control study contained 1070 pairs of 1:1 age-, city-, and gender-matched incident cases and controls (mean age, 71 years) recruited in Guangdong, China. Dietary information was collected using a validated 79-item food frequency questionnaire through face-to-face interviews. DAL was estimated based on established algorithms for the potential renal acid load (PRAL) and net endogenous acid production (NEAP). Higher PRAL and NEAP were dose-dependently associated with a higher risk of hip fracture in both the conditional logistic regression model and restricted cubic spline analysis after adjusting for potential covariates. The multivariate-adjusted odds ratios and 95% CI of hip fracture for tertiles 2 and 3 (vs. 1) of DAL were 1.63 (1.18, 2.25) and 1.92 (1.36, 2.71) for PRAL and 1.81 (1.30, 2.53) and 2.55 (1.76, 3.71) for NEAP in all participants (all p-trends < 0.001), respectively. Subgroup analyses showed more pronounced associations in participants with a lower body mass index. Our findings suggested positive associations between the estimated DAL and the risk of hip fractures in the elderly Chinese population.

Low variability of plant protein intake in the CKiD cohort does not demonstrate changes in estimated GFR nor electrolyte balance

BACKGROUND

Vegetable or plant-based sources of protein may confer health benefits in children with progressive kidney disease. Our aims were to understand the effect of the proportion of vegetable protein intake on changes in estimated GFR and to understand the effect of the proportion of vegetable protein intake on serum levels of bicarbonate, phosphorus, and potassium.

METHODS

Children with baseline eGFR between 30 and 90 mL/min/1.73 m² were recruited from 59 centers across North America as part of the chronic kidney disease in children (CKiD) study. The percentage of dietary vegetable protein (VP%) was gathered from annual Food Frequency Questionnaires. We performed longitudinal linear mixed models to determine the effect of VP% on eGFR and longitudinal logistic mixed models to determine the effect of VP% on electrolyte balance (potassium, phosphorus, bicarbonate).

RESULTS

Two thousand visits from 631 subjects. Across all dichotomized groups of children (sex, African American race, Hispanic ethnicity, glomerular etiology of CKD, hypertension, anemia, hyperkalemia, hyperphosphatemia, acidosis, BMI < 95th percentile), the median VP% was 32-35%. The longitudinal mixed model analysis did not show any effect of VP% on eGFR electrolyte (bicarbonate, phosphorus, and potassium) abnormalities (p > 0.1).

CONCLUSIONS

A diverse cohort of children with CKD has a narrow and homogeneous intake of vegetable protein. Due to the low variability of plant-based protein in the cohort, there were no associations between the percentage of plant protein intake and changes in eGFR nor electrolyte balance. A higher resolution version of the Graphical abstract is available as Supplementary information.

The Importance of Recognizing and Addressing the Spectrum of Acid Stress

Acid accumulation sufficient to reduce plasma bicarbonate concentration, thereby recognized as chronic metabolic acidosis, harms bones and muscles and appears to enhance progression of CKD. Evolving evidence supports that progressive acid accumulation that is not enough to cause chronic metabolic acidosis nevertheless has deleterious effects. Measurable acid retention without reduced plasma bicarbonate concentration, called eubicarbonatemic acidosis, also appears to cause kidney injury and exacerbate CKD progression. Furthermore, chronic engagement of mechanisms to mitigate the ongoing acid challenge of net acid-producing diets of developed societies also appears to be deleterious, including for kidney health. This review challenges clinicians to consider the growing evidence for a spectrum of acid-accumulation disorders that include lesser degrees of acid accumulation than metabolic acidosis yet are harmful. Further research will develop clinically useful tools to identify individuals suffering from these earlier stages of acid stress and determine if the straightforward and comparatively inexpensive intervention of dietary acid reduction relieves or eliminates the harm they appear to cause.

Acid-Mediated Kidney Injury Across the Spectrum of Metabolic Acidosis

Metabolic acidosis affects about 15% of patients with chronic kidney disease. As kidney function declines, the kidneys progressively fail to eliminate acid, primarily reflected by a decrease in ammonium and titratable acid excretion. Several studies have shown that the net acid load remains unchanged in patients with reduced kidney function; the ensuing acid accumulation can precede overt metabolic acidosis, and thus, indicators of urinary acid or potential base excretion, such as ammonium and citrate, may serve as early signals of impending metabolic acidosis. Acid retention, with or without overt metabolic acidosis, initiates compensatory responses that can promote tubulointerstitial fibrosis via intrarenal complement activation and upregulation of endothelin-1, angiotensin II, and aldosterone pathways. The net effect is a cycle between acid accumulation and kidney injury. Results from small- to medium-sized interventional trials suggest that interrupting this cycle through base administration can prevent further kidney injury. While these findings inform current clinical practice guidelines, large-scale clinical trials are still necessary to prove that base therapy can limit chronic kidney disease progression or associated adverse events.

Regulation of Acid-Base Balance in Patients With Chronic Kidney Disease

Normallly the kidneys handle the daily acid load arising from net endogenous acid production from the metabolism of ingested animal protein (acid) and vegetables (base). With chronic kidney disease, reduced acid excretion by the kidneys is primarily due to reduced ammonium excretion such that when acid excertion falls below acid porduction, acid accumulation occurs. With even mild reductions in glomerular filtration rate (60 to 90 ml/min), net acid excretion may fall below net acid production resulting in acid retention which may be initially sequestered in interstitial compartments in the kidneys, bones, and muscles resulting in no fall in measured systemic bicarbonate levels (eubicarbonatemic metabolic acidosis). With greater reductions in kidney function, the greater quantities of acid retained spillover systemically resulting in low pH (overt metabolic acidosis). The evaluation of acid-base balance in patients with CKD is complicated by the heterogeneity of clinical acid-base disorders and by the eubicarbonatemic nature of the early phase of acid retention. If supported by more extensive studies, blood gas analyses to confirm the acid-base disorder and newer ways for assessing the presence of acidosis such as urinary citrate measurements may become routine tools to evaluate and treat acid-base disorders in individuals with CKD.

The Effect of Dietary Intervention on Autosomal-Dominant Polycystic Kidney Disease (ADPKD) Patients on Tolvaptan and Their Quality of Life

Background and objective

Autosomal-dominant polycystic kidney disease (ADPKD) is the most common inherited renal disorder; it affects people of all ethnic groups and is found in up to 10% of patients with end-stage renal disease (ESRD). Dietary intervention is important in people with renal disease, and it has been linked to greater estimated glomerular filtration rate (eGFR) preservation. Tolvaptan, an orally-active nonpeptide, selective arginine vasopressin (AVP) V2R antagonist, was recently licensed in numerous countries for the treatment of ADPKD. The aim of this study was to assess the role of dietary intervention in decreasing the osmotic load on the urine volume and its impact on the quality of life (QOL) of patients with ADPKD on tolvaptan.

Methods

This prospective cohort study was carried out at a Hamilton nephrology genetics clinic. ADPKD patients on well-tolerated doses of tolvaptan for three months were included in the study. Gitelman and Bartter Symptom Health-related QOL questionnaire was used among the study participants.

Results

Our study consisted of nine adult patients with ADPKD who were on a stable dose of tolvaptan therapy. Patients had laboratory values for urine volume, sodium (Na), and urea. No significant difference was found between pre- and post-diet intervention values in 24-hour urine volume (5.9 vs. 5.49 L/d; p=0.423), urine Na (p=0.174), and 24-hour urine urea (p=0.404).

Conclusion

Dietary intervention in ADPKD patients on tolvaptan therapy can play a vital role in improving their QOL. Further research including interventional studies and clinical trials with larger sample sizes is needed to gain deeper insight into the subject.

Modifiable Lifestyle Behaviors and CKD Progression: A Narrative Review

Living a healthy lifestyle is one of the safest and most cost-effective ways to improve one's quality of life and prevent and/or manage chronic disease. As such, current CKD management guidelines recommend that patients adhere to a healthy diet, perform ≥150 minutes per week of physical activity, manage their body weight, abstain from tobacco use, and limit alcohol. However, there are limited studies that investigate the relationship between these lifestyle factors and the progression of CKD among people with established CKD. In this narrative review, we examine the reported frequencies of health lifestyle behavior engagement among individuals with non-dialysis-dependent CKD and the existing literature that examines the influences of diet, physical activity, weight management, alcohol consumption, and tobacco use on the progression of CKD, as measured by decline in GFR, incident ESKD, or elevated proteinuria or albuminuria in individuals with CKD. Many of the available studies are limited by length of follow-up and small sample sizes, and meta-analyses were limited because the studies were sparse and had heterogeneous classifications of behaviors and/or referent groups and of CKD progression. Further research should be done to determine optimal methods to assess behaviors to better understand the levels at which healthy lifestyle behaviors are needed to slow CKD progression, to investigate the effect of combining multiple lifestyle behaviors on important clinical outcomes in CKD, and to develop effective techniques for behavior change. Despite the lack of evidence of efficacy from large trials on the ability of lifestyle behaviors to slow CKD progression, maintaining a healthy lifestyle remains a cornerstone of CKD management given the undisputed benefits of healthy lifestyle behaviors on cardiovascular health, BP control, and survival.

Plant-Based Diets and Peritoneal Dialysis: A Review

Whole food plant-based diets are gaining popularity as a preventative and therapeutic modality for numerous chronic health conditions, including chronic kidney disease, but their role and safety in end-stage kidney disease patients on peritoneal dialysis (PD) is unclear. Given the general public's increased interest in this dietary pattern, it is likely that clinicians will encounter individuals on PD who are either consuming, considering, or interested in learning more about a diet with more plants. This review explores how increasing plant consumption might affect those on PD, encompassing potential benefits, including some specific to the PD population, and potential concerns.

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.

Association between Frequency of Consumption of Pork Se’i and Chronic Kidney Disease in East Nusa Tenggara, Indonesia

BACKGROUND: As a country with various cultures, Indonesia has several regional specialties, one of which is Pork Se’i from East Nusa Tenggara. Studies showed that higher intake of red and processed meat was significantly associated with an increased risk for incident chronic kidney disease (CKD). AIM: This study was conducted with the goal to find out the relationship between consumption of Pork Se’i and water intake with CKD among patient in RSUD W.Z. Johannes, Kupang, East Nusa Tenggara, Indonesia. METHODS: This research was an observational study with a case–control design involving 92 respondents at W.Z Hospital Johannes in the period of July 2020. The determination of consumption of Pork Se’i and water was acquired through the use of Semi Quantitative Food Frequency Questionnaire as an instrument. Chi-square test was used as a statistical test for this study. RESULTS: In the case group, more than half of the respondents (58.7%) were male, while in the control group, more than half of the respondents (60.9%) were female. More than half (58.7%) of case group respondents consume water <1 L/day. More than half (58.7%) of case group respondents consume water <1 L/day, while most of the control group respondents (73.9%) consumed 1 L of water/day. The Pearson Chi-square test showed significant relationship between water consumption and CKD (p = 0.003). The frequency of consumption of Pork Se’i in the case group respondents was mostly in the sometimes (47.8%) and usually (47.8%) categories. Only a small proportion of case respondents (4.3%) rarely consume Pork Se’i. There was a significant relationship between consumption of Pork Se’i with CKD (p = 0.014). CONCLUSIONS: Our study found that consumption of Pork Se’i has a significant correlation with CKD.

Serum bicarbonate is associated with kidney outcomes in autosomal dominant polycystic kidney disease

BACKGROUND

Metabolic acidosis accelerates progression of chronic kidney disease, but whether this is also true for autosomal dominant polycystic kidney disease (ADPKD) is unknown.

METHODS

Patients with ADPKD from the DIPAK (Developing Interventions to halt Progression of ADPKD) trial were included [n = 296, estimated glomerular filtration rate (eGFR) 50 ± 11 mL/min/1.73 m2, 2.5 years follow-up]. Outcomes were worsening kidney function (30% decrease in eGFR or kidney failure), annual eGFR change and height-adjusted total kidney and liver volumes (htTKV and htTLV). Cox and linear regressions were adjusted for prognostic markers for ADPKD [Mayo image class and predicting renal outcomes in ADPKD (PROPKD) scores] and acid-base parameters (urinary ammonium excretion).

RESULTS

Patients in the lowest tertile of baseline serum bicarbonate (23.1 ± 1.6 mmol/L) had a significantly greater risk of worsening kidney function [hazard ratio = 2.95, 95% confidence interval (CI) 1.21-7.19] compared with patients in the highest tertile (serum bicarbonate 29.0 ± 1.3 mmol/L). Each mmol/L decrease in serum bicarbonate increased the risk of worsening kidney function by 21% in the fully adjusted model (hazard ratio = 1.21, 95% CI 1.06-1.37). Each mmol/L decrease of serum bicarbonate was also associated with further eGFR decline (-0.12 mL/min/1.73 m2/year, 95% CI -0.20 to -0.03). Serum bicarbonate was not associated with changes in htTKV or htTLV growth.

CONCLUSIONS

In patients with ADPKD, a lower serum bicarbonate within the normal range predicts worse kidney outcomes independent of established prognostic factors for ADPKD and independent of urine ammonium excretion. Serum bicarbonate may add to prognostic models and should be explored as a treatment target in ADPKD.

Sugar-sweetened beverage consumption and mortality of chronic kidney disease: results from the US National Health and Nutrition Examination Survey, 1999–2014

Background

The relationship between intake of sugar-sweetened beverages (SSBs) and the risk of death in patients with chronic kidney disease (CKD) is unclear. We evaluated the association between SSB intake and subsequent overall mortality in CKD patients.

Methods

We included data from 3996 CKD patients who participated in the 1999–2014 National Health and Nutrition Examination Survey (NHANES). SSB intake was assessed by a 24-h dietary recall, grouped as none, >0 to <1 serving/day, 1 to <2 servings/day and ≥2 servings/day. After adjusting for demographic variables, lifestyle, diet and comorbidities, Cox proportional risk regressions were applied to analyze the associations between the daily intake of SSBs as well as added sugar from beverages and all-cause mortality.

Results

In the whole research population, the median age at baseline was 67 years, 22% were Black and 54% were female. A total of 42% had stage 3 CKD. During an average follow-up period of 8.3 years, a sum of 1137 (28%) deaths from all causes was recorded. The confounder-adjusted risk of mortality was associated with an increase of 1 serving/day of SSBs, with all-cause mortality of 1.18 [95% confidence interval (95% CI)1.08–1.28], and intakes of increased 20-g added sugar/1000 kcal of total energy per day were associated with all-cause mortality of 1.14 (1.05–1.24). Equivalently substituting 1 serving/day of SSBs with unsweetened coffee [HR (95% CI) 0.82 (0.74–0.91)], unsweetened tea [HR (95% CI) 0.86 (0.76–0.98)], plain water [HR (95% CI) 0.79 (0.71–0.88)], or non- or low-fat milk [HR (95% CI) 0.75 (0.60–0.93)] were related to a 14–25% reduced risk of all-cause mortality.

Conclusion

Findings suggest that in the CKD population, increased SSB intake was associated with a higher risk of mortality and indicated a stratified association with dose. Plain water and unsweetened coffee/tea might be possible alternatives for SSBs to avert untimely deaths.

Plant-based Diets in Kidney Disease: Nephrology Professionals' Perspective

OBJECTIVE

Plant-based diets can delay the progression of chronic kidney disease (CKD) and help manage complications and co-morbid conditions such as hypertension, acidosis, diabetes, and cardiovascular disease. However, it is unclear how often plant-based diets are recommended to patients with kidney disease. The objective of this study was to understand nephrology professionals' familiarity, perception, and recommendation of plant-based diets to people with kidney disease.

DESIGN AND METHODS

A survey to understand perception of recommendation of plant-based diets for patients with CKD was developed. Nephrology professionals from the National Kidney Foundation's member directory were e-mailed a link to complete the survey online. This directory includes professionals who work in a variety of nephrology settings, including both CKD and end-stage renal disease care. Survey items were evaluated with descriptive statistics. Differences across items were determined using chi-square tests and t-tests.

RESULTS

A total of 3,901 professionals were sent the survey, and 644 completed the survey. A majority were dietitians (58%) and worked in dialysis clinics (54%). Most (88%) had heard of using plant-based diets for kidney disease treatment, and a majority (88%) believed it could improve CKD management, cardiovascular disease (90%), hypertension (90%), diabetes (84%), high cholesterol (90%), and obesity (84%). Dietitians were more likely to report plant-based diets as beneficial for each health condition (P < .05). Professionals were most confident that a plant-based diet could help control hypertension (3.75 ± 0.99 on a scale of 1-5), compared with delaying progression of CKD (3.68 ± 1.15) or treating acidosis (3.68 ± 1.13). Dietitians felt more confident in their ability to plan a balanced plant-based diet compared with other specialties (3.49 vs. 2.74, P < .001).

CONCLUSION

Nephrology professionals who work in nondialysis-dependent CKD settings, and those who work with patients on dialysis, are aware of the benefits of plant-based diets in kidney disease. However, plant-based diets are not routinely being offered as a treatment option. Nephrology practices should work to increase dietitian referrals to offer patients support in transitioning to a plant-based diet.

Diet-dependent acid load associates with mean arterial pressure in a cohort of non-obese, non-black, post-menopausal women

Higher sodium (Na+) intakes are associated with higher blood pressure (BP). Whether this relationship is stronger with diet-dependent acid load (DAL) and in patients with diagnosed hypertension or normal BP is not well determined. We studied 170 postmenopausal women randomized to potassium bicarbonate or placebo till 36 months where 24-hour urine and arterialized blood were collected. We investigated the association of DAL estimated as urinary potential renal acid load (UPRAL) and mean arterial pressure (MAP) using mixed-effects model, adjusting for age, anthropometrics, creatinine clearance, and treatment. Adjusted regression estimates for change in Na+ and UPRAL on MAP after 12 months follow-up were calculated, and further adjustments were made for change in potassium (K+) and body mass index (BMI). MAP was inversely associated with UPRAL (β [95% CI]:-0.11[-0.25,-0.001]). There was effect modification by hypertension (p-interaction=0.04); MAP decreased significantly in normotensives but the association was not significant in hypertensives. A decrease of 0.70 mmHg in MAP (0.13,1.69) per 50 mmol/24 hr reduction in Na+ was noted when the model was adjusted for change in K+. Our results with UPRAL exhibited stronger dose-response for MAP, which remained significant after adjustment for BMI. UPRAL was independently associated with MAP even after adjustment for potential confounders, and the data showed this association to be more pronounced in normotensives. Novelty: • First longitudinal study on the association of UPRAL and MAP • Association was a more robust relationship than between U[Na/K] ratio and MAP • UPRAL may play a significant role in the pathogenesis of primary hypertension.

Insights Into the Molecular Mechanisms of Polycystic Kidney Diseases

Autosomal dominant (AD) and autosomal recessive (AR) polycystic kidney diseases (PKD) are severe multisystem genetic disorders characterized with formation and uncontrolled growth of fluid-filled cysts in the kidney, the spread of which eventually leads to the loss of renal function. Currently, there are no treatments for ARPKD, and tolvaptan is the only FDA-approved drug that alleviates the symptoms of ADPKD. However, tolvaptan has only a modest effect on disease progression, and its long-term use is associated with many side effects. Therefore, there is still a pressing need to better understand the fundamental mechanisms behind PKD development. This review highlights current knowledge about the fundamental aspects of PKD development (with a focus on ADPKD) including the PC1/PC2 pathways and cilia-associated mechanisms, major molecular cascades related to metabolism, mitochondrial bioenergetics, and systemic responses (hormonal status, levels of growth factors, immune system, and microbiome) that affect its progression. In addition, we discuss new information regarding non-pharmacological therapies, such as dietary restrictions, which can potentially alleviate PKD.

Nutrition Intervention for Reduction of Cardiovascular Risk in African Americans Using the 2019 American College of Cardiology/American Heart Association Primary Prevention Guidelines

INTRODUCTION

The 2019 American College of Cardiology/American Heart Association (ACC/AHA) Prevention Guidelines emphasize reduction in dietary sodium, cholesterol, refined carbohydrates, saturated fat and sweetened beverages. We hypothesized that implementing this dietary pattern could reduce cardiovascular risk in a cohort of volunteers in an urban African American (AA) community church, during a 5-week ACC/AHA-styled nutrition intervention, assessed by measuring risk markers and adherence, called HEART-LENS (Helping Everyone Assess Risk Today Lenten Nutrition Study).

METHODS

The study population consisted of 53 volunteers who committed to eat only home-delivered non-dairy vegetarian meals (average daily calories 1155, sodium 1285 mg, cholesterol 0 mg; 58% carbohydrate, 17% protein, 25% fat). Body mass index (BMI) and fasting serum markers of cardiometabolic and risk factors were measured, with collection of any dietary deviation.

RESULTS

Of 53 volunteers, 44 (mean age 60.2 years, 37 women) completed the trial (88%); 1 was intolerant of the meals, 1 completed both blood draws but did not eat delivered food, and 7 did not return for the tests. Adherence to the diet was reported at 93% in the remaining 44. Cardiometabolic risk factors improved significantly, highlighted by a marked reduction in serum insulin (-43%, p = 0.000), hemoglobin A1c (6.2% to 6.0%, p = 0.000), weight and BMI (-10.2 lbs, 33 to 31 kg/m², p = 0.000), but with small reductions of fasting glucose (-6%, p = 0.405) and triglyceride levels (-4%, p = 0.408). Additionally, improved were trimethylamine-N-oxide (5.1 to 2.9 µmol/L, -43%, p = 0.001), small dense low-density lipoprotein cholesterol (LDL) (24.2 to 19.1 mg/dL, -21%, p = 0.000), LDL (121 to 104 mg/dL, -14%, p = 0.000), total cholesterol (TC) (190 to 168 mg/dL, -12%, p = 0.000), and lipoprotein (a) (LP(a)) (56 to 51 mg/dL, -11%, p = 0.000); high sensitivity C-reactive protein (hs-CRP) was widely variable but reduced by 16% (2.5 to 2.1 ng/mL, p = NS) in 40 subjects without inflammatory conditions. Soluble urokinase plasminogen activator (suPAR) levels were not significantly changed. The ACC/AHA pooled cohort atherosclerotic cardiovascular disease (ASCVD) risk scores were calculated for 41 and 36 volunteers, respectively, as the ASCVD risk could not be calculated for 3 subjects with low lipid fractions at baseline and 8 subjects after intervention (p = 0.184). In the remaining subjects, the mean 10-year risk was reduced from 10.8 to 8.7%, a 19.4% decrease (p = 0.006), primarily due to a 14% decrease in low-density lipoprotein cholesterol and a 10 mm Hg (6%) reduction in systolic blood pressure.

CONCLUSIONS

In this prospective 5-week non-dairy vegetarian nutrition intervention with good adherence consistent with the 2019 ACC/AHA Guidelines in an at-risk AA population, markers of cardiovascular risk, cardiometabolism, and body weight were significantly reduced, including obesity, low-density lipoprotein cholesterol (LDLc) density, LP(a), inflammation, and ingestion of substrates mediating production of trimethylamine-N-oxide (TMAO). Albeit reduced, hs-CRP and suPAR, were not lowered consistently. This induced a significant decrease in the 10-year ASCVD risk in this AA cohort. If widely adopted, this could dramatically reduce and possibly eradicate, the racial disparity in ASCVD events and mortality, if 19% of the 21% increase is eliminated by this lifestyle change.

Surkan P, Azadbakht L. Associations between dietary acid load and obesity among Iranian women

Introduction: Diet-induced acid load may be associated with overweight and obesity as well as with diet quality. We aimed to study how dietary acid load is associated with overweight, obesity and diet quality indices in healthy women.

Methods: We randomly selected 306 healthy 20 to 55 year-old women from health centers affiliated with Tehran University of Medical Science. They were enrolled in a cross-sectional study between June2016 and March 2017. Potential renal acid load (PRAL), net endogenous acid production (NEAP) and dietary acid load (DAL) were calculated for each person. Dietary quality index international (DQI-I),mean adequacy ratio (MAR), and energy density (ED) were estimated. Anthropometry was measured using standard protocols. Nutritional data were obtained from food frequency questionnaires (FFQ). We used multivariable logistic regression models to assess dietary acid load indices in relation to overweight, obesity and abdominal adiposity.

Results: Participants had a mean age of 32.4 years. The number and percentage of women who were overweight, obese and who had abdominal obesity were 94(30.7), 38(12.4) and 126(41.2), respectively.The odds of obesity (adjusted odds ratio; Adj. OR = 2.41, 95% confidence interval; CI:1.01-5.74,P = 0.045) and abdominal adiposity (Adj. OR = 2.4, 95% CI:1.34-4.60, P = 0.004) increased significantly with tertile of DAL. Other dietary acid load indices (PRAL and NEAP) showed no significant association with obesity, overweight or abdominal obesity. As dietary acid load scores (PRAL, NEAP and DAL)increased, DQI-I and MAR significantly decreased whereas ED significantly increased across tertilesof dietary acid load indices (P < 0.001).

Conclusion: Dietary acid load is associated with obesity and abdominal obesity and is also considered an indicator of diet quality.

Eubicarbonatemic Hydrogen Ion Retention and CKD Progression

Small-scale trials in patients with chronic kidney disease (CKD) 3-5 have shown that hypobicarbonatemic metabolic acidosis promotes progression of CKD. Accordingly, the 2012 KDIGO (Kidney Disease: Improving Global Outcomes) guideline suggests base administration to patients with CKD when serum bicarbonate concentration ([HCO₃ˉ]) is <22 mEq/L (~15% of non–dialysis-dependent patients with CKD). However, individuals with milder CKD largely maintain serum [HCO₃ˉ] within the normal range (eubicarbonatemia) and yet can manifest hydrogen ion (H⁺) retention. Limited data in eubicarbonatemic patients with CKD 2 suggest that base administration ameliorates CKD progression. Furthermore, most patients with moderate and advanced CKD maintain a normal serum [HCO₃ˉ], and of those, the vast majority most likely harbor masked H⁺ retention. The present review probes this expanded concept of metabolic acidosis of CKD: the eubicarbonatemic H⁺ retention or subclinical metabolic acidosis of CKD. It focuses on the high prevalence of the entity, its pathophysiologic features, its clinical course, and recent work on potential biomarkers of the condition. Further, it puts forward the urgent task of investigating definitively whether treatment with alkali of eubicarbonatemic H⁺ retention delays CKD progression. If proven true, such knowledge would trigger a paradigm shift in the indication for alkali therapy in CKD.

The Continuum of Acid Stress

Acid-related injury from chronic metabolic acidosis is recognized through growing evidence of its deleterious effects, including kidney and other organ injury. Progressive acid accumulation precedes the signature manifestation of chronic metabolic acidosis, decreased plasma bicarbonate concentration. Acid accumulation that is not enough to manifest as metabolic acidosis, known as eubicarbonatemic acidosis, also appears to cause kidney injury, with exacerbated progression of CKD. Chronic engagement of mechanisms to mitigate the acid challenge from Western-type diets also appears to cause kidney injury. Rather than considering chronic metabolic acidosis as the only acid-related condition requiring intervention to reduce kidney injury, this review supports consideration of acid-related injury as a continuum. This "acid stress" continuum has chronic metabolic acidosis at its most extreme end, and high-acid-producing diets at its less extreme, yet detrimental, end.

Ketogenic Diets and Chronic Disease: Weighing the Benefits Against the Risks

Very-low-carbohydrate ketogenic diets have been long been used to reduce seizure frequency and more recently have been promoted for a variety of health conditions, including obesity, diabetes, and liver disease. Ketogenic diets may provide short-term improvement and aid in symptom management for some chronic diseases. Such diets affect diet quality, typically increasing intake of foods linked to chronic disease risk and decreasing intake of foods found to be protective in epidemiological studies. This review examines the effects of ketogenic diets on common chronic diseases, as well as their impact on diet quality and possible risks associated with their use. Given often-temporary improvements, unfavorable effects on dietary intake, and inadequate data demonstrating long-term safety, for most individuals, the risks of ketogenic diets may outweigh the benefits.

How important is dietary management in chronic kidney disease progression? A role for low protein diets

High dietary protein intake may lead to increased intraglomerular pressure and glomerular hyperfiltration, which in the long-term can lead to de novo or aggravating preexisting chronic kidney disease (CKD). Hence, a low protein diet (LPD, 0.6 to 0.8 g/kg/day) is recommended for the management of CKD. There are evidences that dietary protein restriction mitigate progression of CKD and retard the initiation of dialysis or facilitate incremental dialysis. LPD is also helpful to control metabolic derangements in CKD such as metabolic acidosis and hyperphosphatemia. Recently, a growing body of evidence has emerged on the benefits of plant-dominant low-protein diet (PLADO), which composed of > 50% plant-based sources. PLADO is considered to be helpful for relieving uremic burden and metabolic complications in CKD compared to animal protein dominant consumption. It may also lead to favorable alterations in the gut microbiome, which can modulate uremic toxin generation along with reducing cardiovascular risk. Alleviation of constipation in PLADO may minimize the risk of hyperkalemia. A balanced and individualized dietary approach for good adherence to LPD utilizing various plant-based sources as patients' preference should be elaborated for the optimal care in CKD. Periodic nutritional assessment under supervision of trained dietitians should be warranted to avoid protein-energy wasting.