Relationship between carbohydrate-to-fat intake ratio and the development of chronic kidney disease: A community-based prospective cohort study

Background & aims: It is well-known that high protein intake is associated with renal hyperfiltration and faster renal function decline, but the association of other macronutrients, carbohydrate and fat, with development of chronic kidney disease (CKD) is still inconclusive. Therefore, we aimed to examine the relationship between fat-to-carbohydrate intake ratio (F/C ratio) and incident CKD.

Methods: We included 9226 subjects from the Korean Genome and Epidemiology Study. The subjects were divided into two groups depending on 1 g protein intake per ideal body weight per day. Primary exposure was the F/C ratio defined as calorie intake of fat/calorie intake of fat and carbohydrate. The primary outcome was the development of CKD, which was defined as an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m² and/or proteinuria (≥1+).

Results: During a median follow-up duration of 11.4 years, 778 (8.4%) CKD events occurred. Subjects in the lowest F/C ratio tertile had faster eGFR decline rate than other tertiles. In multivariable Cox analysis, a significantly higher CKD risk was observed in the lowest tertile when protein intake > 1 g/kg/day (hazard ratio [HR] for T1 (<16.1%) vs. T3 (>21.5%), 1.38; 95% confidence interval [CI], 1.03-1.84; P = 0.031). In sensitivity analysis, subjects maintained low F/C ratio diet (<16.1%) during 4 years showed higher risk of subsequent CKD development than those maintained high F/C ratio diet (≥16.1%; HR, 1.70; 95% CI, 1.10-2.63; P = 0.018). In cubic spline analysis, CKD risk was sharply increased in F/C ratio <16.1%, but the risk was nearly constant in F/C ratio ≥16.1%.

Conclusions: A diet with a low F/C ratio was associated with increased risk of CKD in the general population. Therefore, it is necessary to limit excessive high carbohydrate and low fat intake to prevent CKD development in this population.