#2971 LONG-TERM EFFECTS OF THE NEW NORDIC RENAL DIET ON PHOSPHOROUS HOMEOSTASIS IN PATIENTS WITH CHRONIC KIDNEY DISEASE STAGE 3 AND 4

Abstract Background and Aims Chronic kidney disease (CKD) causes severe disturbances in phosphate metabolism. The New Nordic Renal Diet (NNRD) is a whole food approach designed by our group, with low dietary phosphorus content (850 mg/day). In a 1-week study, NNRD had positive effects on phosphorus homeostasis in patients with CKD stage 3-4 [1]. The aim of the present study was to examine the long-term health effects of a dietary intervention with NNRD in patients with CKD stage 3-4 [2]. Method A 26-week randomized, controlled, non-blinded trial comparing the effect of NNRD vs. non-restricted habitual diet. Patients in the NNRD group received weekly home delivery of fresh food items (free of charge) and recipes for five days of the week, and on the remaining two days they were instructed to prepare meals according to the NNRD food principles. The study was designed with seven follow-up visits in the outpatient clinic where fasting blood samples and 24-hour urine collection were delivered. Linear mixed-effects models were used to assess the effects of the intervention, time, and the potential interaction between intervention and time. The primary endpoint was the difference in 24-hour urine phosphorus excretion between the two study groups. Secondary endpoints included fractional phosphorus excretion and plasma fibroblast growth factor 23 (p-FGF23). Results Sixty patients (mean age 54 years, 31 women) with mean eGFR of 34 ml/min/1.73 m2 were included. Two patients were withdrawn due to dialysis initiation. In the NNRD-group (n = 29), mean 24-hour urine phosphorus excretion during the intervention period was 651 mg (SD, 35 mg) vs. 930 mg (SD, 84 mg) in the control group (n = 29), between-group difference 279 (95% CI; -372, -91; P < 0.001) (Figure 1). Mean fractional phosphorus excretion was 11% (SD, 5%) in the NNRD-group and 14% (SD, 7%) in the control group, between-group difference 3% (95% CI; -6.4, -0.8; P = 0.01). Mean p-FGF23 was 162 pg/ml (SD, 130 pg/ml) in the NNRD-group and 215 pg/ml (SD, 230 pg/ml) in the control group, between-group difference 52 pg/ml (95% CI; -100, 73; P = 0.03). P-urea was 3.4 mmol/L lower in the NNRD group (95% CI; -5.3, -0.2, P = 0.03). P-albumin was 1.1 g/L higher in the NNRD group (95% CI; 0.02, 2.4; P = 0.04) and 24-h urine bicarbonate excretion was 4.1 mmol higher in the NNRD group (95% CI; 0.7, 7.5, P = 0.01). There was no difference between study groups in p-phosphorous, p-creatinine, p-potassium, p-calcium, p-lipids, or proteinuria. Conclusion NNRD intervention in the context of fresh food delivery and recipes was feasible and had a major beneficial effect on phosphorous parameters in patients with CKD 3-4.