The Impact of Dietary Acid Load (DAL) on Kidney Function with Stage 4–5 Chronic Kidney Disease: A Cross-Sectional Study in Padang, Indonesia

Background: Chronic Kidney Disease (CKD) is characterized by a progressive and irreversible decline in glomerular filtration rate (GFR), accompanied by disruptions in acid–base homeostasis, both of which may be exacerbated by an elevated dietary acid load (DAL). Persistent metabolic acidosis resulting from high DAL has been implicated in the acceleration of renal functional deterioration, muscle catabolism, and bone demineralization in patients with advanced CKD. Notwithstanding the growing body of evidence linking DAL to CKD progression in other settings, research systematically examining the influence of dietary acid burden in individuals with advanced-stage CKD remains limited in the Indonesian context.

Aims: This study aimed to investigate the association between DAL and indices of kidney function among patients with stage 4–5 CKD.

Patients and Methods: A cross-sectional analytical study was conducted at Dr. M. Djamil General Hospital, Padang, Indonesia, involving 80 patients diagnosed with stage 4–5 CKD. Dietary intake was assessed through two non-consecutive 24-hour dietary recall interviews, and DAL was estimated utilizing the validated Net Endogenous Acid Production (NEAP) formula. Bivariate analyses and multivariate binary logistic regression were employed to examine associations between DAL tertiles and renal function parameters, adjusting for potential confounders.

Results: Higher DAL was associated with lower GFR and elevated serum urea and creatinine concentrations. Following full multivariate adjustment, individuals in the highest DAL tertile demonstrated a significantly increased odds of reduced GFR relative to those in the lowest tertile (OR: 8.55; 95% CI: 1.63 – 44.79; p = 0.017). Statistically significant dose–response trends were additionally observed for elevated serum urea (p = 0.023) and serum creatinine (p = 0.032) across increasing DAL tertiles, indicating a consistent and progressive relationship between dietary acid burden and markers of renal functional impairment

Conclusions: These findings indicate that an elevated dietary acid burden may constitute a significant and modifiable contributing factor to the decline in kidney function observed in patients with advanced CKD. Dietary modification aimed at reducing acid load—particularly through optimization of the balance between animal- and plant-derived protein sources and the enhancement of dietary potassium intake—may offer a clinically feasible and evidence-based nutritional strategy to attenuate metabolic acidosis and decelerate CKD progression. Prospective longitudinal studies with larger sample sizes are warranted to further elucidate the differential effects of animal- versus plant-based protein consumption on DAL and to establish causal directionality in this association.