Dietary Acid-Base Load and Risk of Chronic Kidney Disease in Adults: Tehran Lipid and Glucose Study.

INTRODUCTION: The objective was to examine whether dietary acid load was associated with chronic kidney disease (CKD) in adults.

MATERIALS AND METHODS: The cross-sectional analyses included 4564 participants, aged 20 years and older, who participated in the 4th phase of the Tehran Lipid and Glucose Study and had complete dietary and serum creatinine data. Dietary data were obtained from using a 147-item food-frequency questionnaire. Dietary acid load was calculated as the potential renal acid load (PRAL). Anthropometrics, blood pressure, and fasting plasma glucose, and lipids were measured. Chronic kidney disease was defined as an estimated glomerular filtration rate (GFR) less than 60 mL/min/1.73 m2 calculated using the Modification of Diet in Renal Disease equation. Risk of CKD was obtained in quartiles of PRAL with logistic recreation.

RESULTS: The mean dietary PRAL of the participants was -22.0 mEq/d. After adjustment for age, sex, and body mass index, the odds ratio for CKD in the highest compared to the lowest quartile of PRAL was 1.38 (95% confidence interval [CI], 1.02 to 1.83). After additional adjustment for energy intake and smoking, the odds ratio for CKD in the 4th quartile of PRAL compared to the 1st was 1.42 (95% CI, 1.06 to 1.91). In the final model, after additional adjustment for dietary intake of total fat, carbohydrate, dietary fiber, fructose, sodium, diabetes mellitus, and hypertension, the risk of CKD in the highest dietary PRAL category, compared to the lowest, increased by 42%.

CONCLUSIONS: After adjusting for possible confounding factors, we found that higher PRAL (more acidic diet) was associated with higher prevalent CKD in Iranian adults.