Effects of a Low-PRAL Modified New Nordic Renal Diet on Acid-Base Status in Patients With Stage 4-5 Chronic Kidney Disease and Chronic Metabolic Acidosis.

OBJECTIVE

Metabolic acidosis is a common complication in chronic kidney disease (CKD) and is associated with accelerated disease progression. Diets with a low potential renal acid load (PRAL) represent a promising non-pharmacological strategy to mitigate metabolic acidosis. The New Nordic Renal Diet (NNRD), a plant-focused, low-phosphorus diet, improves acid-base status in patients with CKD stage 3-4. This study evaluated the effects of a two-week, low-PRAL modified NNRD in patients with advanced CKD and chronic metabolic acidosis.

DESIGN AND

METHODS

Twelve patients with CKD stage 4-5 and metabolic acidosis completed a prospective, sequential dietary intervention consisting of three consecutive two-week periods: habitual diet (control), low-PRAL modified NNRD (intervention), and free-living follow-up without dietary guidance. The intervention consisted of individualized low-PRAL recipes. Fasting blood samples, 24-hour urine collections, and clinical measures were obtained throughout the study.

RESULTS

During the intervention, PRAL and net endogenous acid production decreased significantly (-17.2 mmol/day, 95% CI: -23.1 to -11.3 and -17.4, 95% CI: -23.3 to -11.3, respectively). No changes in plasma tCO2 were observed. Net acid excretion decreased slightly (4.1 mmol/d, 95% CI: -8.2 to -0.1). Clinically meaningful reductions were noted in albuminuria (-22.1%, 95% CI: -32.3 to -10.4), and systolic blood pressure (-17 mmHg, 95% CI: -22 to -12).

CONCLUSION

A two-week low-PRAL NNRD reduced dietary acid load but did not correct chronic metabolic acidosis in patients with CKD stage 4-5. This likely reflects severely diminished renal acid excretory capacity in late-stage CKD, where endogenous acid production still exceeds the renal capacity.