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

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.