The plant-based new Nordic renal diet may reduce renal excretion of phosphate, acids, and uremic toxins in patients with stage 3-4 chronic kidney disease, investigators report.
In a randomized crossover trial, 18 patients with an estimated glomerular filtration rate of 16-45 mL/min/1.73 m2 received 7 days of a habitual Danish diet and 7 days of the new Nordic renal diet with a washout period in between.
The Nordic diet improved parameters of phosphate homeostasis over the short term, Louise Salomo, PhD, of University Hospital of Copenhagen in Rigshospitalet, Denmark, and colleagues reported in Nephrology Dialysis Transplantation. It significantly reduced 24-h urine phosphorus excretion by 313 mg/d. At baseline, the mean phosphorus level was 875 mg/d. The level decreased by 400 vs 87 mg/d during the Nordic renal diet and habitual diet periods, respectively. Compared with a typical Danish diet, the new Nordic renal diet significantly reduced 24-hour urine fractional excretion of phosphorus by 11% and FGF23 by 30 pg/mL.
In a post hoc analysis, the investigators further found that the Nordic renal diet improved metabolic acidosis and reduced uremic toxins. By 7 days, it had significantly decreased 24-hour urine net acid excretion by 80% and 24-hour urine excretion of ammonium by 34%, compared with the control period, Nikita Misella Hansen, MSc, of University Hospital of Copenhagen in Denmark, and colleagues reported in the Journal of Renal Nutrition. The renal diet significantly increased bicarbonate by 678% and plasma total CO2 by 8%.
In addition, 24-hour urine excretion of the uremic toxins indoxyl sulphate and p-cresyl sulphate significantly dropped by 31% and 29%, respectively.
The new Nordic renal diet is plant-based, similar to the Mediterranean diet and the DASH diet, but with protein restriction and phosphate reduction. Investigators removed phosphorus-rich food items, such as rye bread, dairy products, and nuts, and reduced intake of animal-based protein, while still allowing a phosphorus content of approximately 850 mg/d. Compared with a habitual Danish diet, the new Nordic renal diet reduced daily phosphorus intake by approximately 650 mg.
“These results encourage further investigations of the long-term effects of [new Nordic renal diet] on renal protection in patients with CKD,” according to Hansen’s team.
Hansen NM, Berg P, Rix M, et al. The New Nordic Renal Diet induces a pronounced reduction of urine acid excretion and uremic toxins in CKD patients (stage 3 and 4). J Ren Nutr. Published online October 1, 2022. doi:10.1053/j.jrn.2022.09.010
Salomo L, Rix M, Kamper AL, Thomassen JQ, Sloth JJ, Astrup A. Short-term effect of the New Nordic Renal Diet on phosphorus homoeostasis in chronic kidney disease Stages 3 and 4. Nephrol Dial Transplant. 2019 Oct 1;34(10):1691-1699. doi:10.1093/ndt/gfy366