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

Chronic kidney disease (CKD) leads to an accumulation of waste products and causes adverse cardiometabolic effects. We investigated the health effects of the New Nordic Renal Diet (NNRD), a novel meal pattern reduced in phosphorus, protein, and sodium. A 26-wk randomized trial compared the NNRD with a habitual diet. The NNRD group received weekly home deliveries of food and recipes. Monthly study visits included fasting blood samples, 24-h urine samples, blood pressure, and anthropometric measurements. Intention-to-treat analysis used linear mixed-effects models. Sixty patients, mean estimated glomerular filtration rate (eGFR) 34 mL/min/1.73 m2 and body mass index of 25–27 kg/m2, were included and 58 completed. Metabolic syndrome was present in 53% (NNRD group) and 57% (control group). The NNRD group (n = 30) reduced their 24-h urine phosphorus excretion by 19% (−153 mg; 95% confidence interval [CI]: −210, −95), control group (n = 30) (no change), between-group difference −171 mg (95% CI: −233, −109; P < 0.001). Proteinuria was reduced by 39% in the NNRD group (−0.33 g/d; 95% CI: −0.47, −0.18), control group (no change), between-group difference −0.34 g/d (95% CI: −0.52, −0.17; P < 0.001). Plasma urea was reduced by −1.5 mmol/L in the NNRD group (95% CI: −2.1, −0.9), control group (no change), between-group difference −1.4 mmol/L (95% CI: −2.0, −0.7; P < 0.001). Systolic blood pressure fell by −5.2 mmHg in the NNRD group (95% CI: −8.4, −2.1), control group (no change), between-group difference −3.9 mmHg (95% CI; −7.6, −0.2; P = 0.04). The NNRD group lost −1.7 kg (95% CI: −2.6, −0.8), control group (no change), between-group difference −2.0 kg (95% CI: −3.0, −1.0; P < 0.001). There were no effects on eGFR during the 26-wk intervention. NNRD in moderate CKD reduces phosphorus excretion, proteinuria, systolic blood pressure, and weight, mainly by reducing abdominal fat. This trial was registered at clinicaltrials.gov as NCT04579315.