Diet and CKD

Diet and CKD 1.) Fluid intake -Coaching to drink more water may not slow decline in eGFR in adults with stage 3 CKD. [0] -P: 631 Canadian adult patients with CKD3 and baseline urine output of 3.0L, recruited from 9 centers -I: Coached to increase water intake by 1-1.5 L/day for 12 months -C: Coached to maintain baseline water intake for 12 months -O: Mean decline in eGFR was -2.2 for hydration group vs. -1.9 for control group. Hydration group had a mean increase in urine output of 0.6 L/day. A difference of 1 m1/min/1.73m2 was determined to be clinically significant and the study was powered to detect a change of 2 or more at 80%. sources [0] Effect of Coaching to Increase Water Intake on Kidney Function Decline in Adults With Chronic Kidney Disease, Clark et al., JAMA, 2018 2.) Protein restriction 2.0) Background -The "Modification of Diet in Renal Disease' (MDRD) study (1989-1993), the largest RCT to examine effects of LPD on CKD --P: 1585 adults 18-70 ---I: LP diet (0.58 g/kg/day protein) 18-45 months or VLP diet (0.28 g/kg/day protein) ---C: Normal diet (1.3 g/kg/day protein) ---0: Among patients with moderate CKD (25-55), LP diet was associated with a small benefit after 4 months; in patients with severe CKD (13-24), VLP diet was not different than LP diet. Lower BP was not associated with decreased rate of decline overall, but in those with baseline higher proteinuria it had a significant benefit. -In contrast to dietary intake of fat and carbohydrates, higher protein intake modulates renal hemodynamic by increasing renal blood flow and elevating intraglomerular pressure leading to higher GFR and more efficient excretion of protein-derived nitrogenous waste products, aka "glomerular hyperfiltration" ---confirmed in a systematic review and meta-analysis of 30 RCTs comparing parameters of renal function in subjects without CKD on HP vs LP/NP diets [01 ---Increased GFR -Increased serum urea -Increased urinary Ca excretion --Increased serum uric acid 2.1) No Dialysis -GFR ›=30 (CKD 1-3) ---Limit to 1.3 g/kg [1] -GFR <30 (CKD 4-5) ---Limit to 0.8-1 g/kg IBW [1,2] -Diabetes is risk equivalent to CKD 4-5 [11 2.2) Dialysis -HD ---1.1-1.4 g/kg IBW [2] -PD ---1-1.2 g/kg IBW [2] 2.3) VLPD -<0.6-0.8 g/kg/day not recommended. [3] -VLPD vs. LPD reduced risk of progression but not all-cause mortality in adults with moderate-to-severe nondiabetic CD [4] -VLPD might increase mortality [5] sources [0] Comparison of High vs. Normal/Low Protein Diets on Renal Function in Subjects without Chronic Kidney Disease: A Systematic Review and Meta-Analysis, Schwingshackl and Hoffmann, PLoS One, 2014 [1] KDIGO CKD working group 2012 level 2c [2] Renal Association grade 1C [3] NICE, 2014 [4] Cochrane Systematic Review, 2018 [51 Am J Kidney Dis 2009 3. Electrolyte restriction -Sodium ---Limit salt intake to <2g/day of sodium (5g Nac1) in adult patients (KDIGO, level 1c) ---Low salt intake decreases BP in adults with CKD (Cochrane 2015) -Phosphate ---Limit dietary phosphate intake alone or in combination with other treaments (KDIGO level 2d) ---Limit to <800-1000 mg/day (NEJM, 2017) 4. Fruit and vegetable intake -Base-inducing fruit and vegetable intake may help to reduce decline in GFR as effectively as sodium bicarbonate in patients with CKD3-4 (dynamed level 3) [0] -Base-inducing produce includes: apples, apricots, oranges, peaches, pears, raisins, strawberries, carrots, cauliflower, eggplant, lettuce, potatoes, spinach, tomatoes, and zucchini sources [0] Treatment of metabolic acidosis in patients with stage 3 chronic kidney disease with fruits and vegetables or oral bicarbonate reduces urine angiotensinogen and preserves glomerular filtration rate, Goraya et al., Kidney Int 2014