Foods With Added Fiber Lower Serum Creatinine Levels in Patients With Chronic Kidney Disease

Objective To determine the effect of foods with added fiber on blood urea nitrogen (BUN) and serum creatinine concentrations in patients with chronic kidney disease (CKD). Design Participants were enrolled in a 6-week single-blind crossover study. Setting Free living with partial dietary intervention. Patients Thirteen CKD patients with Modification of Diet in Renal Disease formula–based estimated glomerular filtration rate (eGFR) ≤50 mL/minute/1.73 m2 at the time of screening (5 men, 8 women; mean age, 67.0 ± 14.8 years) completed the study. Intervention Patients consumed control foods (cereal, cookies, and bars) providing 1.6 g/day fiber daily for 2 weeks, followed by similar foods providing 23 g/day fiber daily for 4 weeks, incorporated into their usual diets. Main Outcome The main outcome of the study was the determination of the impact of foods with added fiber on BUN and serum creatinine levels. Results Consuming foods with added fiber resulted in a 10.6% decrease in mean BUN concentration (13.8 ± 2.0 to 12.1 ± 1.8 mmol/L or 38.5 ± 5.6 to 34.0 ± 5.1 mg/dL; P < .05). Serum creatinine level decreased from a baseline value of 216 ± 26 to 201 ± 23 mmol/L (2.44 ± 0.30 to 2.27 ± 0.26 mg/dL; P < .05) after 2 weeks of fiber-containing food consumption, and remained significantly lower at 195 ± 23 mmol/L (2.21 ± 0.26 mg/dL) after 4 weeks of the intervention ( P < .05). Calculated eGFR increased from a baseline value of 29.6 ± 3.5 to 31.4 ± 3.8 mL/minute/1.73 m2 at the end of 2 weeks, and remained higher at 32.5 ± 3.6 mL/minute/1.73 m2 after 4 weeks of fiber intervention ( P < .05). Conclusion We conclude that increasing fiber intake in CKD patients through the consumption of foods with added fiber may reduce serum creatinine levels and improve eGFR. Additional studies are warranted to confirm these findings and to determine whether the changes are due to direct effects on kidney function.