Dietary acid load and chronic kidney disease in elderly adults: Protein and potassium intake

BACKGROUND: Dietary net endogenous acid production (NEAP), which represents total dietary load of nonvolatile acid, may affect kidney function. Estimated NEAP (eNEAP) is calculated indirectly by the ratio of protein and potassium intake. A few studies are available assessing the association between eNEAP and chronic kidney disease (CKD), and its relation to dietary protein and potassium intake in the elderly. METHODS: A total 1,369 community-dwelling elderly Koreans in the Kangbuk Samsung Cohort Study (KSCS) were evaluated using a food frequency questionnaire (FFQ) and comprehensive health examination. We evaluated the association between eNEAP and the CKD. We also examined their relation to protein and potassium intake. RESULTS: eNEAP was correlated with potassium intake (r = -0.410, P < 0.001), but was not correlated with protein intake (r = -0.004, P = 0.879). In a full multivariate adjustment for sociodemographic factors, dietary factors, and comorbidities, the participants with higher eNEAP quartiles (Q2, Q3, Q4) had higher odds of CKD compared to the lowest eNEAP quartile (Q1); OR (95% CI) were 1.47 (0.78–2.72), 1.66 (0.85–3.23), and 2.30 (1.16–4.60) respectively (P for trend = 0.019). The odds of CKD decreased for participants with higher potassium intake quartiles (Q2, Q3, Q4) compared to the lowest potassium intake quartile (Q1); OR (95% CI) were 0.52 (0.28–0.95), 0.50 (0.26–0.96), and 0.50 (0.21–0.99) respectively (P for trend = 0.050). Protein intake was not associated with CKD. The association between eNEAP and CKD was similar in subgroup analysis. CONCLUSION: Dietary acid load was associated with CKD. Among the nutrients related to dietary acid load, potassium intake was negatively associated with CKD, but protein intake was not associated with CKD in elderly adults.