Nordic chronic kidney disease diet enhances health-related quality of life

By Dr. Liji Thomas, MDReviewed by Benedette Cuffari, M.Sc.Jul 1 2024

Chronic kidney disease (CKD) is a debilitating condition that affects the emotional, physical, and social well-being of affected patients, thereby reducing their quality of life (QoL). A new study published in the journal Nutrients examines how health-related QoL (HRQoL) in CKD patients is affected by the New Nordic Renal Diet (NNRD).

Study: Health-related quality of life during 26-week intervention with the New Nordic Renal Diet. Image Credit: monticello / Shutterstock.com

What is the NNRD?

The NNRD, created to help patients with moderate CKD, is a modified version of the New Nordic Diet (NND), a Scandinavian alternative to the Mediterranean diet.

The NNRD consists of 80% plant-based foods, with the remaining foods comprised of animal products that provide 30-35 kcal/day. The amount and type of each food is customized to the patient.

A previous randomized controlled trial (RCT) reported the favorable effects of NNRD on metabolic and physiologic outcomes. More specifically, CKD patients prescribed the NNRD had lower protein and phosphorus levels in their urine, loss of fat mass, and lowered blood pressure.

Healthy diets recommended to CKD patients are often restricted and target single nutrients. In contrast, the NNRD comprises a nutritionally balanced approach.

Although the feasibility and effectiveness of the NNRD have been previously reported, its impact on the HRQoL of CKD patients remains unclear. This type of patient-reported outcome measure (PROM) is valuable in evaluating medical interventions from the patient’s perspective.

About the study

The current study included 58 participants who ate according to a control diet or the NNRD. NNRD participants received weekly recipes and food boxes consistent with the specified diet, whereas controls continued to consume their usual diet.

HRQoL was assessed at the start of the study and the end of the 26-week intervention.

What did the study show?

People on the NNRD lost a mean of -1.7 kg after 26 weeks, which was equivalent to a 2% reduction in body mass and a two-kg difference between the two groups. The NNRD also reduced body mass index (BMI) values compared to controls.

The NNRD group observed a 5% and 2.5% reduction in body fat mass and lean mass, respectively. Waist circumference measurements were reduced by over one centimeter in the NNRD group, with a -2.1 cm difference from the control group.

The NNRD group experienced 26% less pain and discomfort during the intervention period, compared to no change reported in the control group. A positive association was observed between loss of body fat mass and reduced pain/discomfort.

The ease of performing daily activities improved by 23% in the NNRD group, with no change reported in the control group.

To evaluate the degree of compliance, urine phosphorus levels were measured for 24 hours. The NNRD group exhibited about 20% lower phosphorus levels compared to the control group, which showed no change. As phosphorus levels in the urine decreased, greater improvement in daily activities was observed.

The study findings indicate that the NNRD provides adequate protein intake at 0.8 g protein/kg/day without causing loss of muscle mass. In fact, NNRD group participants exhibited 39% lower urinary protein excretion. Plasma and urine urea and urinary sodium levels were also reduced in the NNRD group, whereas plasma albumin levels rose.

Conclusions

The NNRD group had a clinically relevant improvement in various HRQoL outcomes.”

NNRD group participants reported better HRQoL, energy, mood, sleep quality, and skin health. These benefits could be attributed to reduced medication requirements for hypertension, as blood pressure levels were reduced with NNRD compliance.

Although weight loss was not a goal of the program, about 2% of the participant’s body weight was lost during the 26-week intervention. With less body fat, the participants experienced less pain and discomfort, thus suggesting a beneficial effect of fat mass reduction. The observed fat loss was primarily in the abdominal region, as indicated by waist circumference measurements.

Polyphenols and other antioxidants in the NNRD, like those in the Mediterranean diet, may also have contributed to the improved HRQoL. Polyunsaturated fatty acids in this type of diet are anti-inflammatory and may activate neurotransmitters in the brain, thereby improving mental health.

The involvement of counselors to monitor diet compliance, the use of recipes created by famous chefs, and the provision of free fresh food every week may have motivated the participants and enhanced their enjoyment of the food. This approach also fosters self-management rather than passive reception of medical care or knowledge, which could also contribute to a higher HRQoL.