Effect of glycemic index and carbohydrate intake on kidney function in healthy adults. Issue 1 (December 2016)

• Record Type: Journal Article
• Authors: Juraschek, Stephen; Chang, Alex; Appel, Lawrence; Anderson, Cheryl; Crews, Deidra; Thomas, Letitia; Charleston, Jeanne; Miller, Edgar
• Is Part Of: BMC nephrology. Volume 17:Issue 1(2016)
• Page Start: 1
• Page End: 10
• Publication Date: 2016-12
• Subjects: β2-microglobulin -- Carbohydrate -- Clinical trial -- Creatinine -- Cystatin C -- Diet -- Estimated glomerular filtration rate -- Glycemic index; Kidneys -- Diseases -- Periodicals; 616.61005
• DOI: 10.1186/s12882-016-0288-5
• Languages: English
• ISSNs: 1471-2369

Abstract

Abstract Background Replacing carbohydrate with protein acutely increases glomerular filtration rate (GFR) but is associated with faster, long-term kidney disease progression. The effects of carbohydrate type (i.e. glycemic index, GI) on kidney function are unknown. Methods We conducted an ancillary study of a randomized, crossover feeding trial in overweight/obese adults without diabetes or kidney disease (N = 163). Participants were fed each of four healthy, DASH-like diets for 5 weeks, separated by 2-week washout periods. Weight was kept constant. The four diets were: high GI (GI ≥65) with high %carb (58 % kcal) (reference diet), low GI (≤45) with low %carb (40 % kcal), low GI with high %carb; and high GI with low %carb. Plasma was collected at baseline and after each feeding period. Study outcomes were cystatin C, β2-microglobulin (β2M), and estimated GFR based on cystatin C (eGFRcys). Results Mean (SD) age was 52 (11) years; 52 % were women; 50 % were black. At baseline, mean (SD) cystatin C, β2M, and eGFRcys were 0.8 (0.1) mg/L, 1.9 (0.4) mg/L, and 104 (16) mL/min/1.73 m2 . Compared to the high GI/high %carb diet, reducing GI, %carb, or both increased eGFRcys by 1.9 mL/min/1.73 m2 (95 % CI: 1.1, 2.7;P < 0.001), 3.0 mL/min/1.73 m2 (1.9, 4.0;P < 0.001), and 4.5 mL/min/1.73 m2 (3.5, 5.4;P < 0.001), respectively. Increases in eGFRcys from reducing GI were significantly associated with increases in eGFRcys from reducing %carb (P < 0.001). Results for cystatin C and β2M reflected eGFRcys. Conclusions Reducing GI increased GFR. Reducing %carb by increasing calories from protein and fat, also increased GFR. Future studies on GI should examine the long-term effects of this increase in GFR on kidney injury markers and clinical outcomes. Trial registration Clinical Trials.gov, number:NCT00608049 (first registered January 23, 2008)