Dietary Approach to Stop Hypertension (DASH) diet and risk of renal function decline and all-cause mortality in renal transplant recipients

A holistic review of sodium intake in kidney transplant patients: More questions than answers

Kidney transplantation (KT) is the best treatment option for end-stage kidney disease (ESKD). Acute rejection rates have decreased drastically in recent years but chronic kidney allograft disease (CKAD) is still an important cause of allograft failure and return to dialysis. Thus, there is unmet need to identify and reverse the cause of CKAD. Additionally, cardiovascular events after KT are still leading causes of morbidity and mortality. One overlooked potential contributor to CKAD and adverse cardiovascular events is increased sodium/salt intake in kidney transplant recipients (KTRs). In general population, the adverse effects of high sodium intake are well known but in KTRs, there is a paucity of evidence despite decades of experience with KT. Limited research showed that sodium intake is high in most KTRs. Moreover, excess sodium intake is associated with elevated blood pressure and albuminuria in some studies involving KTRs. There is also experimental evidence suggesting that increased sodium intake is associated with histologic graft damage. Critical knowledge gaps still remain, including the exact amount of sodium restriction needed in KTRs to optimize outcomes and allograft survival. Additionally, best methods to measure sodium intake and practices to follow-up are not clarified in KTRs. To meet these deficits, prospective long term studies are warranted in KTRs. Moreover, preventive measures must be determined and implemented both at individual and societal levels to achieve sodium restriction in KTRs.

Current Evidence on Dietary Factors and Kidney Allograft Function in Kidney Transplant Recipients: A Systematic Review

BACKGROUND

Currently, there is no accounted-for consensus and practical standard when counseling diet modification for kidney transplant recipients (KTRs). There are many differences between transplant centers regarding what KTRs are needed to follow a diet, what dietary factors and supplements are allowed, and how long KTRs should follow a modified diet. Relatively few scatter data are available for dietary factors in KTRs. Thus, we aimed to systematically review the literature on the purported dietary factors for kidney function.

METHODS

A systematic literature search was performed between February and March 2022 and updated in February 2023 using PubMed, Scopus, Web of Science, and Google Scholar. We included human observational and interventional studies that evaluated a dietary factor on kidney function and graft survival in KTRs. Data were extracted, and the risk of bias was assessed using established tools relevant to the study design.

RESULTS

Of the 5341 citations retrieved, seven prospective cohorts, five cross-sectional, seventeen randomized, and ten non-randomized clinical trials were included that evaluated seven purported dietary factors. Almost half of the studies (n = 22; 56%) were classified as having a low degree of bias and sufficient support. Twenty-one studies (54%) reported a positive effect on KTRs. DASH and Mediterranean diets decreased graft failure, low-sodium diet reduced blood pressure, and antioxidants improved creatinine, GFR, and graft function. Of these, only twelve studies (31%) were at low risk of bias.

CONCLUSION

Some dietary factors, including DASH, Mediterranean, moderate protein, and low-- sodium diet, as well as antioxidants, may be associated with improved survival and kidney function in KTRs. However, more research is needed.

Association of Three Different Dietary Approaches to Stop Hypertension Diet Indices with Renal Function in Renal Transplant Recipients

Several dietary indices assess the impacts of the Dietary Approaches to Stop Hypertension (DASH) diet on health outcomes. We explored DASH adherence and renal function among 85 Taiwanese renal transplant recipients (RTRs) in a cross-sectional study. Data collection included demographics, routine laboratory data, and 3-day dietary records. Three separate DASH indices, that defined by Camões (based on nine nutrients), that defined by Fung (using seven food groups and sodium), and that modified by Fung (as above but separated for men and women) were used. Renal function was ascertained through the estimated glomerular filtration rate (eGFR) from patients' medical records. Participants' mean age was 49.7 ± 12.6 years and eGFR was 54.71 ± 21.48 mL/min/1.73 m2. The three established DASH diet indices displayed significant correlations (r = 0.50-0.91) and indicated the nutritional adequacy of the diet. Multiple linear regressions indicated a significant positive association between higher DASH scores for each index and increased eGFR. In addition, RTRs in the highest DASH score tertile had higher eGFR rates than those in the lowest tertile, regardless of confounding variables. Adherence to a DASH-style diet correlated with better renal function among RTRs. Educating RTRs about the DASH diet may prevent graft function deterioration.

Vegetable Intake, but Not Fruit Intake Is Inversely Associated With Fasting Plasma Glucose in Kidney Transplant Recipients

BACKGROUND

The association between dietary intake and glycemic control has been extensively investigated in type 2 diabetes. However, little is known about this association in kidney transplant recipients (KTRs).

METHODS

We performed an observational study involving 263 adult KTRs with a functioning allograft for at least 1 year at the outpatient clinic of the Hospital from November 2020 to March 2021. Dietary intake was assessed by food frequency questionnaire. Linear regression analyses were performed to evaluate the association between fruit and vegetable intake and fasting plasma glucose.

RESULTS

The vegetable and fruit intake were 238.24 g/d (102.38-416.67) and 511.94 g/d (321.19-849.05), respectively. The fasting plasma glucose was 5.15 ± 0.95 mmol/L. The linear regressions revealed that vegetable intake, but not fruit intake was inversely associated with fasting plasma glucose in KTRs (adjusted R2 = 0.203, P < .001). The clear dose-response relation was observed. Moreover, each 100 g increase in vegetable intake was associated with 11.6% reduction of fasting plasma glucose.

CONCLUSIONS

Vegetable intake, but not fruit intake, is inversely associated with fasting plasma glucose in KTRs.

The dietary patterns derived by reduced-rank regression in association with Framingham risk score and lower DASH score in Hoveyzeh cohort study

The relationship between dietary patterns (DPs) and cardiovascular disease (CVD) has been the subject of much research, but given the significance of this disease, studying the factors affecting it through different methodological considerations is of utmost importance. This study aimed to investigate the association between the four dietary patterns (DPs) derived from reduced-rank regression (RRR) and the risk of CVD predicted by the Framingham Risk Score (FRS) in the Arab residence of Khuzestan, Iran. Furthermore, the predefined Dietary Approaches to Stop Hypertension (DASH) would be used as a comparative model to assess the validity of the extracted DPs. In this cross-sectional study, 5799 individuals aged 35-70 without a CVD diagnosis were selected among the participants of the Hoveyzeh cohort study (HCS). The Risk of CVD was assessed using the FRS model. A semi-quantitative food frequency questionnaire evaluated dietary intake. Four DPs were derived using RRR with 28 food groups as predictors and total protein (g/d), fiber(g/d), fat(g/d), and magnesium intake (mg/d) as response variables. Multinomial and binary logistic regression were used to assess the relationship of DPs with intermediate (10-20%) and high (> 20%) levels of FRS and lower DASH scores (< 4.5), respectively. Four primary DPs were derived, which explained 89.10 of the total explained variance in participants' dietary intake. Multinomial regression was applied between FRS (10-20%) and (> 20%) across quartiles of four identified DPs. After adjustment for potential confounders, higher tendency to 1st and 2nd DPs in Model 1, OR = 4.67 (95% CI 3.65; 6.01), OR = 1.42 (95% CI 1.13; 1.79) were presented accordingly. The 1st DP, characterized by higher intake of refined grains and lower intake of vegetables oil, sugar, mayonnaise and artificial juices, the 2nd DP characterized by higher intake of hydrogenated fat and lower consumption of tomato sauce and soft drink was associated with greater odds of CVD with the intermediate level of FRS. However, higher adherence to the 3rd DP, characterized by higher intake of fruits, vegetables and legumes and lower intake of fish, egg, red meat, processed meat, mayonnaise, sugar and artificial juices, the 4th DP characterized by higher intake of coffee, nuts and lower intake of sugar, mayonnaise and artificial juices was associated with a lower risk of FRS. Moreover, lower DASH score considered in binary logistic regression across quartiles of four identified dietary patterns. 1st and 2nd DPs were directly related to lower DASH scores, while 3rd and 4th DPs had high comparability with the DASH diet and inversely contributed to the lower DASH score. Total DASH score was significantly correlated to four derived DPs. Our findings confirm the current knowledge regarding the beneficial effects of healthy plant-based DPs and the avoidance of high-fat and processed foods to prevent CVD.

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.

Cardiovascular disease risk factors and lifestyle modification strategies after pediatric kidney transplantation: what are we dealing with, and what can we target?

Kidney transplantation in pediatric patients can lead to partial improvement of some of the cardiometabolic parameters that increase the risk for cardiovascular disease (CVD) in patients with chronic kidney disease. However, even after restoration of kidney function, transplant recipients remain at risk for CVD due to the continual presence of traditional and non-traditional risk factors, including the side effects of immunosuppression and chronic inflammation. This educational review describes the prevalence of CVD risk factors in pediatric kidney transplant recipients and presents available evidence for therapeutic lifestyle changes and other non-pharmacologic strategies that can be used to improve traditional and modifiable CVD risk factors. Although trial-grade evidence for interventions that improve CVD in pediatric kidney transplant recipients is limited, potential strategies include lowering dietary sodium and saturated fat intake and increasing physical activity levels. Intensive follow-up may help patients achieve guideline-recommended goals for reducing their overall CVD risk.

Dietary quality indices and recurrent chronic kidney disease in Taiwanese post-renal transplant recipients

Background

This study investigated the association between dietary quality indices and recurrent chronic kidney disease (rCKD) in Taiwanese post-renal transplant recipients (RTRs).

Methods

This prospective study recruited RTRs aged >18 years with a functioning allograft and without any acute rejection in the past 3 months from September 2016 to June 2018. Dietary quality indices included the Alternative Healthy Eating Index (AHEI) and AHEI-2010, and the Taiwanese version of the AHEI (AHEI-Taiwan) was calculated using 3-day dietary records, and calculated scores were divided into quartiles. Laboratory data were collected from medical records. rCKD was defined as an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m². Logistic regression analysis was performed to analyze the associations.

Results

This study included 102 RTRs. The RTRs with higher AHEI, AHEI-Taiwan, and AHEI-2010 scores were older and had higher eGFRs and lower odds of rCKD. As compared with the lowest quartile, patients with the highest quartiles of the AHEI [odds ratio (OR), 0.10; 95% confidence interval (95% CI): 0.02, 0.49; p-trend = 0.004), AHEI-2010 (OR, 0.17; 95% CI: 0.04, 0.72; p-trend = 0.016], and AHEI-Taiwan (OR, 0.13; 95% CI: 0.03-0.59; p-trend = 0.008) had lower odds of rCKD, respectively. As compared with the lowest quartile, patients who consumed the highest quartiles of red and processed meat had 11.43 times higher odds of rCKD (OR, 11.43; 95% CI: 2.30-56.85; p for trend <0.01).

Conclusion

Higher dietary quality indices are associated with lower odds of rCKD in Taiwanese RTRs. Particularly, a positive association between a higher intake of red meat and processed meat and higher odds of rCKD remained exists after transplantation in Taiwanese RTRs. Further dietary guidelines and individualized dietary education were necessary for RTRs to prevent graft function deterioration.

Nutrition Disturbances and Metabolic Complications in Kidney Transplant Recipients: Etiology, Methods of Assessment and Prevention-A Review

Nutrition disturbances occur at all stages of chronic kidney disease and progress with the decrease of the kidney filtration rate. Kidney transplantation (KTx) as the best form of kidney replacement therapy poses various nutritional challenges. Prior to transplantation, recipients often present with mild to advanced nutrition disturbances. A functioning allograft not only relieves uremia, acidosis, and electrolyte disturbances, but also resumes other kidney functions such as erythropoietin production and vitamin D3 metabolism. KTx recipients represent a whole spectrum of undernutrition and obesity. Since following transplantation, patients are relieved of most dietary restrictions and appetite disturbances; they resume old nutrition habits that result in weight gain. The immunosuppressive regimen often predisposes them to dyslipidemia, glucose intolerance, and hypertension. Moreover, most recipients present with chronic kidney graft disease at long-term follow-ups, usually in stages G2-G3T. Therefore, the nutritional status of KTx patients requires careful monitoring. Appropriate dietary and lifestyle habits prevent nutrition disturbances and may improve kidney graft function. Despite many nutritional guidelines and recommendations targeted at chronic kidney disease, there are few targeted at KTx recipients. We aimed to provide a brief review of nutrition disturbances and known nutritional recommendations for kidney transplant recipients based on the current literature and dietary trends.

Arterial hypertension in kidney transplantation: huge importance, but few answers

Abstract Arterial hypertension (AH) after renal transplantation (RTX) is correlated with worse cardiovascular and renal outcomes, with loss of renal function, decreased graft survival and higher mortality. RTX recipients have discrepant blood pressure (BP) values when measured in the office or by systematic methodologies, such as Ambulatory Blood Pressure Monitoring (ABPM), with significant prevalence of no nocturnal dipping or nocturnal hypertension, white coat hypertension and masked hypertension. The aim of the present study was to review the issue of hypertension in RTX, addressing its multifactorial pathophysiology and demonstrating the importance of ABPM as a tool for monitoring BP in these patients. Treatment is based on lifestyle changes and antihypertensive drugs, with calcium channel blockers considered first-line treatment. The best blood pressure target and treatment with more favorable outcomes in RTX are yet to be determined, through well-conducted scientific studies, that is, in terms of AH in RTX, we currently have more questions to answer than answers to give.

Hipertensão arterial no transplante renal: grande importância, mas poucas respostas

Resumo Hipertensão arterial (HA) no póstransplante renal (TXR) se correlaciona com piores desfechos cardiovasculares e renais, com perda de função renal, diminuição da sobrevida do enxerto e maior mortalidade. Receptores de TXR apresentam valores discrepantes de pressão arterial (PA) quando ela é obtida em consultório ou por metodologias sistematizadas, como a Monitorização Ambulatorial da PA (MAPA), com prevalências significantes de ausência de descenso noturno ou hipertensão noturna, hipertensão do avental branco e hipertensão mascarada. O objetivo do presente estudo foi rever a temática da hipertensão no TXR, abordando sua fisiopatologia multifatorial e demonstrando a importância da MAPA como ferramenta de acompanhamento da PA nesses pacientes. O tratamento é baseado em mudanças no estilo de vida e em fármacos anti-hipertensivos, sendo os bloqueadores de canais de cálcio considerados de primeira linha. A melhor meta pressórica e o tratamento com desfechos mais favoráveis no TXR ainda estão por ser determinados, por meio de estudos bem conduzidos cientificamente, ou seja, em termos de HA no TXR temos atualmente mais questões a responder do que respostas a dar.

Donor obesity and weight gain after transplantation: two still overlooked threats to long-term graft survival

The effect of donor obesity on kidney transplantation success has long been an overlooked clinical research area. Even though there is no strict guideline in most countries prohibiting donation from obese individuals, most candidates with a body mass index >35-40 kg/m² are rejected due to concerns regarding long-term renal functional deterioration in the donor. The effects of excessive fat mass on renal function and allograft survival have been analysed by several longitudinal and follow-up studies. These studies have documented the deleterious effect on long-term graft outcomes of excessive body mass in living kidney donors and de novo obesity or pre-existing obesity worsening after transplantation on kidney outcomes. However, there is a paucity of clinical trials aimed at countering overweight and obesity in living and deceased kidney donors and in transplant patients. In this review we will briefly discuss the mechanism whereby fat excess induces adverse kidney outcomes and describe the effects on graft function and survival in living obese donors.

Ultra-processed foods and risk of all-cause mortality in renal transplant recipients

BACKGROUND

Renal transplant recipients (RTRs) have a 6-fold higher risk of mortality than age- and sex-matched controls. Whether high consumption of ultra-processed foods is associated with survival in RTRs is unknown.

OBJECTIVES

We aimed to study the association between high consumption of ultra-processed foods and all-cause mortality in stable RTRs.

METHODS

We conducted a prospective cohort study in adult RTRs with a stable graft. Dietary intake was assessed using a validated 177-item FFQ. Food items were categorized according to the NOVA classification system and the proportion ultra-processed foods comprised of total food weight per day was calculated.

RESULTS

We included 632 stable RTRs (mean ± SD age: 53.0 ± 12.7 y, 57% men). Mean ± SD consumption of ultra-processed foods was 721 ± 341 g/d (28% of total weight of food intake), whereas the intake of unprocessed and minimally processed foods, processed culinary ingredients, and processed foods accounted for 57%, 1%, and 14%, respectively. During median follow-up of 5.4 y [IQR: 4.9-6.0 y], 129 (20%) RTRs died. In Cox regression analyses, ultra-processed foods were associated with all-cause mortality (HR per doubling of percentage of total weight: 2.13; 95% CI: 1.46, 3.10; P < 0.001), independently of potential confounders. This association was independent from the quality of the overall dietary pattern, expressed by the Mediterranean Diet Score (MDS) or Dietary Approaches to Stop Hypertension (DASH) score. When analyzing ultra-processed foods by groups, only sugar-sweetened beverages (HR: 1.21; 95% CI: 1.05, 1.39; P = 0.007), desserts (HR: 1.24; 95% CI: 1.02, 1.49; P = 0.03), and processed meats (HR: 1.87; 95% CI: 1.22, 2.86; P = 0.004) were associated with all-cause mortality.

CONCLUSIONS

Consumption of ultra-processed foods, in particular sugar-sweetened beverages, desserts, and processed meats, is associated with a higher risk of all-cause mortality after renal transplantation, independently of low adherence to high-quality dietary patterns, such as the Mediterranean diet and the DASH diet.This trial was registered at clinicaltrials.gov as NCT02811835.

Nutritional and dietary interventions to prolong renal allograft survival after kidney transplantation

PURPOSE OF REVIEW

Diet plays an important role in slowing progression of chronic kidney disease in native and transplanted kidneys. There is limited evidence on the association on dietary intake with renal allograft function. Mechanisms of major nutrients and dietary patterns with focusing on a plant-based diet related to kidney transplant health and longevity are reviewed.

RECENT FINDINGS

High dietary protein intake may adversely affect renal allograft. Low protein plant-focused diets such as Dietary Approaches to Stop Hypertension, plant-dominant low-protein diet and Mediterranean diets appear associated with favorable outcomes in slowing renal allograft function decline. The mechanism may be related to a change in renal hemodynamic by decreasing glomerular hyperfiltration from low dietary protein intake and plant-based ingredients. Recent observational studies of association between dietary protein intake and kidney allograft outcomes are conflicting. Although strong evidence is still lacking, a low protein diet of 0.6-0.8 g/kg/day with at least 50% of the protein source from plant-based components in kidney transplant recipients with stable kidney allograft function should be considered as the dietary target.

SUMMARY

Dietary intervention with low-protein plant-focused meals may improve outcomes in kidney transplant recipients, but the evidence remains limited and further studies are warranted.

Prerenal Transplant Education and Evaluation Positively Impacts Outcomes

Introduction: An outstanding question in kidney transplantation is how to prepare candidates and their social supports for optimal posttransplant outcomes. Project Aims: This program evaluation assessed whether a pretransplant quality improvement clinic improved clinical outcomes in the year posttransplant compared to recipients receiving standard of care. Design: The Countdown to Transplant Clinic was implemented with kidney transplant candidates expected to receive a transplant within the next few months. The clinic included an enhanced education session on posttransplant lifestyle management, confirmation of support (≥2 adults), and evaluations by transplant social work, psychology, and nephrology. Results: Seventy-five patients participated in the clinic and underwent a transplant. A retrospective chart review of posttransplant laboratory values, rehospitalizations (within 3-months posttransplant), biopsy-confirmed graft failure, and mortality (within 1-year posttransplant) were collected from both groups. Univariate and multivariate propensity score-weighted linear or logistic regression models were used to evaluate the association between clinic participation and outcomes. In models adjusting for relevant covariates, participation in The Countdown to Transplant Clinic (vs standard care) was associated with a lower coefficient of variation of serum tacrolimus (all values collected 3-12 months posttransplant), 30-day posttransplant white blood cell counts (but not 90-day), 90-day posttransplant potassium, and 30 and 31 to 90 days rehospitalizations. Clinic participation did not predict serum glucose levels at 30- or 90-days posttransplant. Due to low rates of rejection and mortality, meaningful comparisons were not possible. Conclusion: Participation in a pretransplant, multicomponent clinic may improve certain outcomes of interest posttransplantation. Pilot testing for feasibility for randomized controlled trials is a necessary next step.

A Narrative Review of Dietary Approaches for Kidney Transplant Patients

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

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.

Net Endogenous Acid Excretion and Kidney Allograft Outcomes

BACKGROUND AND OBJECTIVES

High dietary acid load may accelerate a decline in kidney function. We prospectively investigated whether dietary acid load is associated with graft outcomes in kidney transplant recipients, and whether venous bicarbonate mediates this association.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We used data from 642 kidney transplant recipients with a functioning graft ≥1 year after transplantation. Net endogenous acid production was estimated using food frequency questionnaires and, alternatively, 24-hour urinary urea and potassium excretion to estimate net endogenous acid production. We defined the composite kidney end point as a doubling of plasma creatinine or graft failure. Multivariable Cox regression analyses, adjusted for potential confounders, were used to study the associations of dietary acid load with the kidney end point. We evaluated potential mediation effects of venous bicarbonate, urinary bicarbonate excretion, urinary ammonium excretion, titratable acid excretion, and net acid excretion on the association between net endogenous acid production and the kidney end point.

RESULTS

The median net endogenous acid production using food frequency questionnaires and net endogenous acid production using urinary excretion were 40 (interquartile range, 35-45) and 54 (interquartile range, 44-66) mEq/day, respectively. During a median follow-up of 5.3 years (interquartile range, 4.1-6.0), 121 (19%) participants reached the kidney end point. After multivariable adjustment, net endogenous acid production using food frequency questionnaires and net endogenous acid production using urinary excretion (per SD higher) were independently associated with higher risk for kidney end point (hazard ratio, 1.33; 95% confidence interval, 1.12 to 1.57, P=0.001 and hazard ratio, 1.44; 95% confidence interval, 1.24 to 1.69, P<0.001, respectively). Baseline venous bicarbonate mediated 20% of the association between net endogenous acid production using food frequency questionnaires and the kidney end point. Baseline venous bicarbonate, urinary ammonium excretion, and net acid excretion mediated 25%, -14%, and -18%, respectively, of the association between net endogenous acid production using urinary excretion and the kidney end point.

CONCLUSIONS

Higher dietary acid load was associated with a higher risk of doubling of plasma creatinine or graft failure, and this association was partly mediated by venous bicarbonate, urinary ammonium, and net acid excretion.

Metabolic syndrome-related dietary pattern and risk of mortality in kidney transplant recipients

BACKGROUND AND AIMS

Presence of the metabolic syndrome (MetS) importantly contributes to excess mortality in kidney transplant recipients (KTRs). However, it is unclear which dietary factors drive the adverse role of MetS in KTRs. We aimed to define a dietary pattern that maximally explained the variation in MetS components, and to investigate the association between this MetS-related dietary pattern (MetS-DP) and all-cause mortality in KTRs.

METHODS AND RESULTS

We included 429 adult KTRs who had a functioning graft ⩾1 year. A MetS-DP was constructed using habitual dietary intake derived from a 177-item food frequency questionnaire. We used reduced rank regression (RRR), and defined the six components of MetS (waist circumference, systolic blood pressure, diastolic blood pressure, serum triglycerides, HbA1c, and HDL cholesterol) as response variables and 48 food groups as predictor variables. We evaluated the association between the MetS-DP and all-cause mortality using multivariable Cox regression analysis. The MetS-DP was characterized by high intakes of processed meat and desserts, and low intakes of vegetables, tea, rice, fruits, milk, and meat substitutes. During a mean follow-up of 5.3 ± 1.2 years, 63 KTRs (14.7%) died. Compared to the lowest tertile of the Mets-DP score, those with the greatest adherence had a more than 3-fold higher risk of all-cause mortality (hazard ratio [HR] = 3.63; 95% confidence interval [CI], 1.70-7.74, P < 0.001), independent of potential confounders.

CONCLUSIONS

We identified a MetS-related dietary pattern which was independently associated with all-cause mortality in KTRs. The association between this dietary pattern and all-cause mortality was mediated by MetS. Clinical trial reg. no. NCT02811835.

Modelling the Cost-Effectiveness of Implementing a Dietary Intervention in Renal Transplant Recipients

Background: The Dietary Approach to Stop Hypertension (DASH) and potassium supplementation have been shown to reduce the risk of death with a functioning graft (DWFG) and renal graft failure in renal transplant recipients (RTR). Unfortunately, a key problem for patients is the adherence to these diets. The aim of this study is to evaluate the cost-effectiveness and budget impact of higher adherence to either the DASH or potassium supplementation. Methods: A Markov model was used to simulate the life course of 1000 RTR in the Netherlands. A societal perspective with a lifetime time horizon was used. The potential effect of improvement of dietary adherence was modelled in different scenarios. The primary outcomes are the incremental cost-effectiveness ratio (ICER) and the budget impact. Results: In the base case, improved adherence to the DASH diet saved 27,934,786 and gained 1880 quality-adjusted life years (QALYs). Improved adherence to potassium supplementation saved €1,217,803 and gained 2901 QALYs. Both resulted in dominant ICERs. The budget impact over a five-year period for the entire Dutch RTR population was €8,144,693. Conclusion: Improving dietary adherence in RTR is likely to be cost-saving and highly likely to be cost-effective compared to the current standard of care in the Netherlands.

Nutrition in Chronic Kidney Disease-The Role of Proteins and Specific Diets

Chronic kidney disease (CKD) is a global public health burden, needing comprehensive management for preventing and delaying the progression to advanced CKD. The role of nutritional therapy as a strategy to slow CKD progression and uremia has been recommended for more than a century. Although a consistent body of evidence suggest a benefit of protein restriction therapy, patients' adherence and compliance have to be considered when prescribing nutritional therapy in advanced CKD patients. Therefore, these prescriptions need to be individualized since some patients may prefer to enjoy their food without restriction, despite knowing the potential importance of dietary therapy in reducing uremic manifestations, maintaining protein-energy status.

Dietary Assessment and Self-Management Using Information Technology in Order to Improve Outcomes in Kidney Transplant Recipients

Big data and artificial intelligence (AI) will transform the way research in nephrology is carried out and consequently improve the performance of clinical practice in nephrology and transplantation. Managing long-term health outcomes in kidney transplant recipients (KTR) includes the improvement of modifiable factors, such as diet. Self-management using information technology (IT) aims to facilitate lifestyle changes, manage symptoms and treatment in the course of chronic kidney disease (CKD) or any chronic condition. The advantages of health mobile applications further include the capacity of data compilation and yielding responses to numerous research questions in nephrology and transplantation. However, studies investigating the employment of such applications in KTR and its impact in kidney transplant outcomes are still lacking. The specific advantages of dietary assessment and self-management using IT in order to improve outcomes in KTR are presently discussed. This Special Issue features a great set of articles regarding IT approaches to improve kidney allograft survival and posttransplant outcomes in all areas.

Inherited salt-losing tubulopathies are associated with immunodeficiency due to impaired IL-17 responses

Increased extracellular sodium activates Th17 cells, which provide protection from bacterial and fungal infections. Whilst high salt diets have been shown to worsen autoimmune disease, the immunological consequences of clinical salt depletion are unknown. Here, we investigate immunity in patients with inherited salt-losing tubulopathies (SLT). Forty-seven genotyped SLT patients (with Bartter, Gitelman or EAST Syndromes) are recruited. Clinical features of dysregulated immunity are recorded with a standardised questionnaire and immunological investigations of IL-17 responsiveness undertaken. The effects of altering extracellular ionic concentrations on immune responses are then assessed. Patients are hypokalaemic and hypomagnesaemic, with reduced interstitial sodium stores determined by ²³Na-magnetic resonance imaging. SLT patients report increased mucosal infections and allergic disease compared to age-matched controls. Aligned with their clinical phenotype, SLT patients have an increased ratio of Th2:Th17 cells. SLT Th17 and Tc17 polarisation is reduced in vitro, yet STAT1 and STAT3 phosphorylation and calcium flux following T cell activation are unaffected. In control cells, the addition of extracellular sodium (+40 mM), potassium (+2 mM), or magnesium (+1 mM) reduces Th2:Th17 ratio and augments Th17 polarisation. Our results thus show that the ionic environment typical in SLT impairs IL-17 immunity, but the intracellular pathways that mediate salt-driven Th17 polarisation are intact and in vitro IL-17 responses can be reinvigorated by increasing extracellular sodium concentration. Whether better correction of extracellular ions can rescue the immunophenotype in vivo in SLT patients remains unknown.

Salt levels in culture affect the polarisation of Th17 cells, which normally protect the host from fungal and bacterial infections. Here, the authors study patients with salt-losing tubulopathies (SLT) to find that, while Th17 immunity is dampened in SLT patients, their Th17-inducing signaling pathways are intact and can be reinvigorated by exogenous salt.

Urinary Excretion of N1-Methylnicotinamide and N1-Methyl-2-Pyridone-5-Carboxamide and Mortality in Kidney Transplant Recipients

It is unclear whether niacin nutritional status is a target for improvement of long-term outcome after renal transplantation. The 24-h urinary excretion of N¹-methylnicotinamide (N¹-MN), as a biomarker of niacin status, has previously been shown to be negatively associated with premature mortality in kidney transplant recipients (KTR). However, recent evidence implies higher enzymatic conversion of N¹-MN to N¹-methyl-2-pyridone-5-carboxamide (2Py) in KTR, therefore the need exists for interpretation of both N¹-MN and 2Py excretion for niacin status assessment. We assessed niacin status by means of the 24-h urinary excretion of the sum of N¹-MN and 2Py (N¹-MN + 2Py), and its associations with risk of premature mortality in KTR. N¹-MN + 2Py excretion was measured in a longitudinal cohort of 660 KTR with LS-MS/MS. Prospective associations of N¹-MN + 2Py excretion were investigated with Cox regression analyses. Median N¹-MN + 2Py excretion was 198.3 (155.9–269.4) µmol/day. During follow-up of 5.4 (4.7–6.1) years, 143 KTR died, of whom 40 due to an infectious disease. N¹-MN + 2Py excretion was negatively associated with risk of all-cause mortality (HR 0.61; 95% CI 0.47–0.79; p < 0.001), and infectious mortality specifically (HR 0.47; 95% CI 0.29–0.75; p = 0.002), independent of potential confounders. Secondary analyses showed effect modification of hs-CRP on the negative prospective association of N¹-MN + 2Py excretion, and sensitivity analyses showed negative and independent associations of N¹-MN and 2Py excretion with risk of all-cause mortality separately. These findings add further evidence to niacin status as a target for nutritional strategies for improvement of long-term outcome in KTR.

Plant-based diets to manage the risks and complications of chronic kidney disease

Traditional dietary recommendations for patients with chronic kidney disease (CKD) focus on the quantity of nutrients consumed. Without appropriate dietary counselling, these restrictions can result in a low intake of fruits and vegetables and a lack of diversity in the diet. Plant nutrients and plant-based diets could have beneficial effects in patients with CKD: increased fibre intake shifts the gut microbiota towards reduced production of uraemic toxins; plant fats, particularly olive oil, have anti-atherogenic effects; plant anions might mitigate metabolic acidosis and slow CKD progression; and as plant phosphorus has a lower bioavailability than animal phosphorus, plant-based diets might enable better control of hyperphosphataemia. Current evidence suggests that promoting the adoption of plant-based diets has few risks but potential benefits for the primary prevention of CKD, as well as for delaying progression in patients with CKD G3-5. These diets might also help to manage and prevent some of the symptoms and metabolic complications of CKD. We suggest that restriction of plant foods as a strategy to prevent hyperkalaemia or undernutrition should be individualized to avoid depriving patients with CKD of these potential beneficial effects of plant-based diets. However, research is needed to address knowledge gaps, particularly regarding the relevance and extent of diet-induced hyperkalaemia in patients undergoing dialysis.

Sport and Exercise in Improving Outcomes After Solid Organ Transplantation: Overview From a UK Meeting

Outcomes after solid organ transplantation continue to improve, but premature loss of life remains a major concern, with death from cerebrovascular disease and cardiovascular disease accounting for around 20% late deaths. There are multiple contributory factors including preexisting, and the posttransplant development of, cardiometabolic conditions (such as hypertension, diabetes mellitus, hyperlipidemia, and obesity). There is accumulating evidence that the regular engagement in exercise is an important factor affecting outcomes before, during, and after transplantation; yet most waitlist candidates and recipients have reduced levels of physical activity. The mechanisms whereby physical activity is associated with better outcomes and a reduction in risk factors for cardiovascular disease are incompletely understood. Attempts to increase physical activity in the transplant population, as in the general population, have had limited success. Use of concepts from Nudge theory provides an evidence-based approach that may help increase physical activity and so reduce premature mortality. Both National and International Transplant Games provide a vehicle for increasing physical activity in this population and may also help to reduce premature death by providing a forum for mutual support for recipients and their families as well as an excellent forum for highlighting the success and impact of organ donation.

Physical Activity and the Development of Post-Transplant Diabetes Mellitus, and Cardiovascular- and All-Cause Mortality in Renal Transplant Recipients

(1) Background: Little is currently known about the health impacts of daily-life moderate-to-vigorous physical activity (MVPA) in relation to the development of post-transplant diabetes mellitus (PTDM) and the long-term survival of renal transplant recipients (RTRs). (2) Methods: We analyzed self-reported data on MVPA within non-occupational and occupational domains, estimated with the SQUASH questionnaire, from a prospective cohort study of RTRs (n = 650) with a functioning graft exceeding 1 year. PTDM diagnoses were based on plasma glucose levels (≥126 mg/dL), HbA1c (≥6.5%), and the use of antidiabetic medication. Mortality data were retrieved from patient files up to the end of September 2015. (3) Results: During a median follow-up period of 5.3 years, 50 patients (10%) developed PTDM and 129 (19.8%) died. Of these deaths, 53 (8.9%) were caused by cardiovascular disease. Cox regression analyses showed that higher MVPA levels among patients were associated with a lower risk of PTDM (hazard ratio (HR); 95% confidence interval (95%CI) = 0.49; 0.25–0.96, p = 0.04), cardiovascular- (0.34; 0.15–0.77, p = 0.01), and all-cause mortality (0.37; 0.24–0.58, p < 0.001) compared with No-MVPA patients, independently of age, sex, and kidney function parameters. Associations of MVPA with cardiovascular and all-cause mortality remained significant and materially unchanged following further adjustments made for transplant characteristics, lifestyle factors, metabolic parameters, medication use, and creatinine excretion (muscle mass). However, the association between MVPA and PTDM was no longer significant after we adjusted for metabolic confounders and glucose levels. (4) Conclusion: Higher MVPA levels are associated with long-term health outcomes in RTRs.

Emerging evidence of an effect of salt on innate and adaptive immunity

Salt intake as part of a western diet currently exceeds recommended limits, and the small amount found in the natural diet enjoyed by our Paleolithic ancestors. Excess salt is associated with the development of hypertension and cardiovascular disease, but other adverse effects of excess salt intake are beginning to be recognized, including the development of autoimmune and inflammatory disease. Over the last decade there has been an increasing body of evidence demonstrating that salt affects multiple components of both the innate and adaptive immune systems. In this review we outline the recent laboratory, animal and human data, highlighting the effect of salt on immunity, with a particular focus on the relevance to inflammatory kidney disease.

Mediating-Moderating Effect of Allostatic Load on the Association between Dietary Approaches to Stop Hypertension Diet and All-Cause and Cause-Specific Mortality: 2001-2010 National Health and Nutrition Examination Surveys

This secondary analysis of survey data examined mediating-moderating effects of allostatic load score (calculated using the Rodriquez method) on the association between nutrient-based Dietary Approaches to Stop Hypertension (DASH) diet score (Mellen Index) and the all-cause and cause-specific mortality risks among 11,630 adults ≥ 30 years of age from the 2001-2010 National Health and Nutrition Examination Surveys with no history of cardiovascular disease or cancer at baseline, and who were followed-up for ~9.35 years. Multivariable models were adjusted for demographic, socioeconomic, lifestyle, and health characteristics. All-cause, cardiovascular disease, and cancer-specific mortality rates were estimated at 6.5%, 1.1%, and 1.9%, respectively. The median DASH total score was 3.0 (range: 1-8) (with 78.3% scoring < 4.5), whereas the median allostatic load score was 3 (range: 0-9). The DASH diet, fiber, and magnesium were negatively correlated with allostatic load, whereas allostatic load predicted higher all-cause mortality, irrespective of the DASH diet. Whereas protein was protective, potassium increased all-cause mortality risk, irrespective of allostatic load. Potassium was protective against cardiovascular disease-specific mortality but was a risk factor for cancer-specific mortality. Although no moderating effects were observed, mediation by the allostatic load on cardiovascular disease-specific mortality was observed for DASH total score and selected component scores. Direct (but not indirect) effects of DASH through the allostatic load were observed for all-cause mortality, and no direct or indirect effects were observed for cancer-specific mortality. From a public health standpoint, the allostatic load may be a surrogate for the preventive effects of the DASH diet and its components on cardiovascular disease-specific mortality risk.

High Dietary Intake of Vegetable Protein Is Associated With Lower Prevalence of Renal Function Impairment: Results of the Dutch DIALECT-1 Cohort

INTRODUCTION

Dietary protein intake may influence development of renal function impairment in diabetes mellitus type 2 (T2DM). We assessed the association between sources of protein and prevalence of renal function impairment.

METHODS

Cross-sectional analyses were performed in baseline data of 420 patients of the DIAbetes and LifEstyle Cohort Twente-1 (DIALECT-1) study. Protein intake was assessed using a Food Frequency Questionnaire, modified for accurate assessment of protein intake, including types and sources of protein. Renal function impairment was defined as estimated glomerular filtration rate (eGFR) <60 ml/min per 1.73 m2 (Chronic Kidney Disease Epidemiology Collaboration formula).

RESULTS

Among 420 patients with T2DM, 99 renal function impairment cases were identified. Multivariate Cox proportional hazard models were used and adjusted for the main lifestyle and dietary factors. The prevalence ratios in the fully adjusted model were 1 (reference), 0.74 (95% confidence interval [CI]: 0.44-1.27; P = 0.28) and 0.47 (95% CI: 0.23-0.98; P = 0.04) according to increasing tertiles of vegetable protein intake. For animal protein intake the prevalence ratios were 1 (reference), 1.10 (95% CI: 0.64-1.88; P = 0.74) and 1.06 (95% CI: 0.56-1.99; P = 0.87) according to increasing tertiles of intake. Theoretical replacement models showed that replacing 3 energy percent from animal protein by vegetable protein lowered the prevalence ratio for the association with renal function impairment to 0.20 (95% CI: 0.06-0.63; P = 0.01).

CONCLUSION

In conclusion, we found that higher intake of vegetable protein was associated with a lower prevalence of renal function impairment, and theoretical replacement of animal protein with vegetable protein was inversely associated with renal function impairment among patients with T2DM.

Nutrition Trends in Kidney Transplant Recipients: the Importance of Dietary Monitoring and Need for Evidence-Based Recommendations

Many physiological properties of the renal system influence nutrient metabolism, elimination, and homeostasis. Kidney failure poses significant challenges to maintaining adequate nutrition, most of which transplantation ameliorates. Comprehensive recommendations for managing nutritional derangements for patients with chronic kidney disease and end stage renal disease exist; however, there are only sparse guidelines for post-transplant malnutrition and adverse outcomes. Not only are guidelines limited, but little is known about dietary trends of post-kidney transplant recipients. This review describes guidelines for prevalent metabolic and nutritional complications post-kidney transplantation and also evaluates changes in caloric intake and diet composition after transplantation. This topic is important because nutrition influences allograft function and a number of cardiovascular risk factors including blood pressure, dyslipidemia, weight, and diabetes. In addition, many dietary recommendations and modifiable lifestyle changes should be tailored for specific complications of transplant patients, namely immunosuppression side effects, dietary restrictions, and electrolyte imbalances.

Dietary Approach to Stop Hypertension (DASH) diet and risk of renal function decline and all-cause mortality in renal transplant recipients

Renal transplant recipients (RTR) are at risk of decline of graft function and premature mortality, with high blood pressure as an important risk factor for both. To study the association of the Dietary Approach to Stop Hypertension (DASH) diet with these adverse events, we conducted a prospective cohort study of adult RTR. Dietary data were collected using a validated 177-item food frequency questionnaire and an overall DASH-score was obtained. We included 632 stable RTR (mean ± standard deviation age 53.0 ± 12.7 years, 57% men). Mean DASH score was 23.8 ± 4.7. During median follow-up of 5.3 (interquartile range, 4.1-6.0) years, 119 (18.8%) RTR had renal function decline, defined as a combined endpoint of doubling of serum creatinine and death-censored graft failure, and 128 (20.3%) died. In Cox-regression analyses, RTR in the highest tertile of the DASH score had lower risk of both renal function decline (hazard ratio [HR] = 0.57; 95% confidence interval [CI], 0.33-0.96, P = .03) and all-cause mortality (HR = 0.52; 95%CI, 0.32-0.83, P = .006) compared to the lowest tertile, independent of potential confounders. Adherence to a DASH-style diet is associated with lower risk of both renal function decline and all-cause mortality. These results suggest that a healthful diet might benefit long-term outcome in RTR.