Health effects of the New Nordic Renal Diet in patients with stage 3 and 4 chronic kidney disease, compared with habitual diet: a randomized trial

The Two Dimensions of Nutrition for the Planet: Environment and Health

PURPOSE OF REVIEW

Protecting the planet is protecting the future. Food production systems are among the most important human activities threatening planetary health. Diet, food systems, the environment, and health are interconnected. Accordingly, this review aims to assess the effects of nutrition on the planet and the relationship between some types of diets defined as sustainable and the planet and human health.

RECENT FINDINGS

Many diets have been proposed to protect the planet and human health, but there is no consensus on which diet is best. It should not be forgotten that planetary health diets, plant-based diets, and vegetarian/vegan diets can reduce environmental pressure. Still, they cannot have the same effect in every country, and these diets may have different effects depending on the differences in the countries' income level, nutritional culture, and food systems. Moreover, it should not be overlooked that these diets may cause difficulties in terms of adaptation, cause deficiencies in some nutrients, and may not be suitable for all segments of society. Sustainable diets such as the Mediterranean and New Nordic, as well as Dietary Approaches to Stop Hypertension, are more flexible and acceptable. Instead of a globally recommended reference diet to protect the planet and human health, each country can analyze its food systems and choose the most appropriate food production methods and sustainable diet style to reduce environmental burden, improve health, and create policies accordingly, which can help achieve sustainable goals faster.

The challenged urine bicarbonate excretion test in cystic fibrosis: A comprehensive analysis of urine acid/base parameters

AIM

Renal excretion of excess HCO3 - depends on renal cystic fibrosis transmembrane conductance regulator (CFTR) and is impaired in people with cystic fibrosis (pwCF). Urine HCO3 - excretion following oral NaHCO3-loading may be a simple in vivo biomarker of CFTR function. In this study, we investigated changes in urine acid/base parameters following oral NaHCO3-loading to comprehensively assess the physiological response to the test and evaluate HCO3 - as the primary test result.

METHODS

Urine acid/base parameters (titratable acid (TA), NH4 +, net acid excretion (NAE) and pH) were measured in bio-banked urine samples from controls (n = 10) and pwCF (n = 50) who completed the challenged urine HCO3 - test. The association between urine acid/base excretion parameters and clinical CF disease characteristics and CFTR modulator therapy-induced changes were assessed.

RESULTS

Before treatment, challenged urine acid/base excretion associated with important CF disease characteristics. TA excretion and NAE were lower in pwCF with residual function mutations, 7.9 and 16.6 mmol/3 h, respectively, and lower TA excretion and NAE associated with pancreatic sufficiency. A lower excretion of TA, NH4 +, and NAE associated with a higher percentage of predicted FEV1 (1.3%, 2.5% and 0.8% per mmol/3 h higher, respectively). Modulator treatment decreased TA excretion and NAE (-2.9 and -5.3 mmol/3 h, respectively).

CONCLUSION

Following acute NaHCO3-loading, increased base excretion is mirrored by decreased acid excretion. Urine HCO3 - excretion sufficiently represents the additional urine acid/base parameters as test result. The observed changes in acid excretion support CFTR modulator-induced increase of CFTR-dependent type B intercalated cell HCO3 - secretion and the use of the challenged urine HCO3 - test as a possible CFTR-biomarker.

A Urine pH-Ammonium Acid/Base Score and CKD Progression

Key Points

This study developed a urine acid/base score to assess tubular acid excretion capacity and identify early acid retention in CKD. The results show that early signs of acid retention (a low acid/base score) are associated with a higher risk for CKD progression. Future research should address if a low urine acid/base score can be improved and if this translates into clinically meaningful effects.

Background

Acidosis is associated with exacerbated loss of kidney function in CKD. Currently, acid/base status is assessed by plasma measures, although organ-damaging covert acidosis, subclinical acidosis, may be present before reflected in plasma. Low urine NH4+ excretion associates with poor kidney outcomes in CKD and is proposed as a marker for subclinical acidosis. However, low NH4+ excretion could result from either a low capacity or a low demand for acid excretion. We hypothesized that a urine acid/base score reflecting both the demand and capacity for acid excretion would better predict CKD progression.

Methods

Twenty-four–hour urine collections were included from three clinical studies of patients with CKD stage 3 and 4: a development cohort (N =82), a variation cohort (N =58), and a validation cohort (N =73). A urine acid/base score was derived and calculated from urinary pH and [NH4+]. Subclinical acidosis was defined as an acid/base score below the lower limit of the 95% prediction interval of healthy controls. The main outcomes were change in measured GFR after 18 months and CKD progression (defined as ≥50% decline in eGFR, initiation of long-term dialysis, or kidney transplantation) during up to 10 years of follow-up.

Results

Subclinical acidosis was prevalent in all cohorts (n =54/82, 48/73, and 40/58, respectively, approximately 67%). Subclinical acidosis was associated with an 18% (95% confidence interval [CI], 2 to 32) larger decrease of measured GFR after 18 months. During a median follow-up of 6 years, subclinical acidosis was associated with a higher risk of CKD progression. Adjusted hazard ratios were 9.88 (95% CI, 1.27 to 76.7) in the development cohort and 11.1 (95% CI, 2.88 to 42.5) in the validation cohort. The acid/base score had a higher predictive value for CKD progression than NH4+ excretion alone.

Conclusions

Subclinical acidosis, defined by a new urine acid/base score, was associated with a higher risk of CKD progression in patients with CKD stage 3 and 4.

Protein Intake and Mortality in Older Adults With Chronic Kidney Disease

Importance

Avoiding high protein intake in older adults with chronic kidney disease (CKD) may reduce the risk of kidney function decline, but whether it can be suboptimal for survival is not well known.

Objective

To estimate the associations of total, animal, and plant protein intake with all-cause mortality in older adults with mild or moderate CKD and compare the results to those of older persons without CKD.

Design, Setting, and Participants

Data from 3 cohorts (Study on Cardiovascular Health, Nutrition and Frailty in Older Adults in Spain 1 and 2 and the Swedish National Study on Aging and Care in Kungsholmen [in Sweden]) composed of community-dwelling adults 60 years or older were used. Participants were recruited between March 2001 and June 2017 and followed up for mortality from December 2021 to January 2024. Those with no information on diet or mortality, with CKD stages 4 or 5, or undergoing kidney replacement therapy and kidney transplant recipients were excluded. Data were originally analyzed from June 2023 to February 2024 and reanalyzed in May 2024.

Exposures

Cumulative protein intake, estimated via validated dietary histories and food frequency questionnaires.

Main Outcomes and Measures

The study outcome was 10-year all-cause mortality, ascertained with national death registers. Chronic kidney disease was ascertained according to estimated glomerular filtration rates, urine albumin excretion, and diagnoses from medical records.

Results

The study sample consisted of 8543 participants and 14 399 observations. Of the 4789 observations with CKD stages 1 to 3, 2726 (56.9%) corresponded to female sex, and mean (SD) age was 78.0 (7.2) years. During the follow-up period, 1468 deaths were recorded. Higher total protein intake was associated with lower mortality among participants with CKD; adjusted hazard ratio (HR) for 1.00 vs 0.80 g/kg/d was 0.88 (95% CI, 0.79-0.98); for 1.20 vs 0.80 g/kg/d, 0.79 (95% CI, 0.66-0.95); and for 1.40 vs 0.80 g/kg/d, 0.73 (95% CI, 0.57-0.92). Associations with mortality were comparable for plant and animal protein (HRs, 0.80 [95% CI, 0.65-0.98] and 0.88 [95% CI, 0.81-0.95] per 0.20-g/kg/d increment, respectively) and for total protein intake in participants younger than 75 years vs 75 years or older (HRs, 0.94 [95% CI, 0.85-1.04] and 0.91 [95% CI, 0.85-0.98] per 0.20-g/kg/d increment in total protein intake, respectively). However, the hazards were lower among participants without CKD than in those with CKD (HRs, 0.85 [95% CI, 0.79-0.92] and 0.92 [95% CI, 0.86-0.98] per 0.20-g/kg/d increment, respectively; P = .02 for interaction).

Conclusions and Relevance

In this multicohort study of older adults, higher intake of total, animal, and plant protein was associated with lower mortality in participants with CKD. Associations were stronger in those without CKD, suggesting that the benefits of proteins may outweigh the downsides in older adults with mild or moderate CKD.

Type 2 Diabetes Mellitus and Cardiometabolic Prospects: A Rapid Narrative Review

Cardiometabolic syndrome (CMS), type 2 diabetes mellitus (T2DM), and cardiovascular diseases are among the major altruists to the international liability of disease. The lifestyle and dietary changes attributable to economic growth have resulted in an epidemiological transition towards non-communicable diseases (NCDs) as the leading causes of death. Low- and middle-income countries (LMICs) bear a more substantial disease burden due to limited healthcare sector capacities to address the rapidly growing number of chronic disease patients. The purpose of this narrative review paper was to explore the interrelationships between CMS, T2DM, and cardiovascular impairments in the context of NCDs, as well as major preventative and control interventions. The role of insulin resistance, hyperglycemia, and dyslipidemia in the pathogenesis of T2DM and the development of severe cardiovascular impairments was highlighted. This paper elaborated on the pivotal role of lifestyle modifications, such as healthy diets and physical activity, as cornerstones of addressing the epidemics of metabolic diseases. Foods high in calories, refined sugar, red meat, and processed and ready-to-eat meals were associated with an amplified risk of CMS and T2DM. In contrast, diets based on fruits, legumes, vegetables, and whole grain, home-cooked foods demonstrated protective effects against metabolic diseases. Additionally, the role of a psychological and behavioral approach in addressing metabolic diseases was highlighted, especially regarding its impact on patient empowerment and the patient-centered approach to preventative and therapeutic interventions.

Health-Related Quality of Life during 26-Week Intervention with the New Nordic Renal Diet

The New Nordic Renal Diet (NNRD) is a whole-food approach, tailored to meet recommended guidelines in patients with moderate chronic kidney disease (stage 3b-4). The NNRD improved various metabolic and physiological endpoints during a 26-week randomized controlled study. Here, we examined the effect of dietary intervention on health-related quality of life (HRQoL). Sixty participants were recruited (NNRD group n = 30, control group n = 30) and 58 completed the study. During the intervention, the NNRD group received food boxes, and recipes once a week. The control group continued their habitual diet. HRQoL was examined at baseline and at the end of the intervention using the validated EuroQol-5D-5L, including a 5-point scale Likert questionnaire at the end of the intervention. Assessed by the EuroQol-5D-5L questionnaire, the NNRD group experienced a reduction in pain/discomfort during the intervention by 26% [-0.44 points (95% CI; -0.73, -0.16)], compared with no change in the control group [0.25 points (95% CI; -0.02, 0.53)] and a between-group difference of -0.70 points (95% CI; -1.03, -0.37, p < 0.001). A larger decrease of body fat mass was associated with a larger decrease in pain/discomfort (p = 0.014). In addition, the NNRD group reported an overall improvement in conducting usual daily activities by 23% [-0.30-point (95% CI; -0.50, -0.11)], while no change was seen in the control group [-0.02 points (95% CI; -0.21, 0.17)], with a between-group difference -0.28 points (95% CI; -0.51, -0.06, p = 0.014). A larger decrease in 24 h urine phosphorus excretion, used as a marker of compliance, was associated with a larger improvement in conducting usual daily activities (p = 0.036). The NNRD group had a clinically relevant improvement in various HRQoL outcomes.

Post-intervention Adherence to the New Nordic Renal Diet among patients with chronic kidney disease, stages 3 and 4

The New Nordic Renal Diet (NNRD) is a meal pattern reduced in phosphorus, protein, and sodium for patients with moderate chronic kidney disease. The NNRD showed improvements in metabolic, and physiological outcomes after 26-weeks intervention. In the original study, participants were randomized to NNRD (n = 30), or control (habitual diet) (n = 30). The aim of this study was to explore adherence to the NNRD 3 months after cessation of intervention (follow-up). Fifty-seven participants completed the follow-up visit, which consisted of fasting blood samples and 24 h urine samples. At follow-up, there was no longer a significant reduction in 24 h urine phosphorus excretion in the NNRD group. From intervention to follow-up, 24 h urine phosphorus increased by 63 mg in the NNRD group, vs. -24.1 mg in the control group, between-group difference 87.1 mg (-10.1, 184.3, p = 0.08). Our findings show that more active intervention is needed to support adherence and maintain beneficial effects of the NNRD.