Better preservation of residual renal function in peritoneal dialysis patients treated with a low-protein diet supplemented with keto acids: a prospective, randomized trial.
BACKGROUND
While a low-protein diet may preserve residual renal function (RRF) in chronic kidney disease (CKD) patients before the start of dialysis, a high-protein intake is usually recommended in dialysis patients to prevent protein-energy wasting. Keto acids, which were often recommended to pre-dialysis CKD patients treated with a low-protein diet, had also been reported to be associated with both RRF and nutrition maintenance. We conducted a randomized trial to test whether a low-protein diet with or without keto acids would be safe and associated with a preserved RRF during peritoneal dialysis (PD).


METHODS
To assess the safety of low protein, we first conducted a nitrogen balance study in 34 incident PD patients randomized to receive in-centre diets containing 1.2, 0.9 or 0.6 g of protein/kg ideal body weight (IBW)/day for 10 days. Second, 60 stable PD patients [RRF 4.04 +/- 2.30 ml/ min/1.73 m(2), urine output 1226 +/- 449 ml/day, aged 53.6 +/- 12.8 years, PD duration 8.8 (1.5-17.8) months] were randomized to receive either a low- (LP: 0.6-0.8 g/kg IBW/day), keto acid-supplemented low- (sLP: 0.6-0.8 g/kg IBW/day with 0.12 g/kg IBW/day of keto acids) or high-protein (HP: 1.0-1.2 g/kg IBW/day) diet. The groups were followed for 1 year and RRF as well as nutritional status was evaluated serially.


RESULTS
A neutral or positive nitrogen balance was achieved in all three groups. RRF remained stable in group sLP (3.84 +/- 2.17 to 3.39 +/- 3.23 ml/min/1.73 m(2), P = ns) while it decreased in group LP (4.02 +/- 2.49 to 2.29 +/- 1.72 ml/min/1.73 m(2), P < 0.05) and HP (4.25 +/- 2.34 to 2.55 +/- 2.29 ml/min/1.73 m(2), P < 0.05). There was no change from baseline on nutritional status in any of the groups during follow-up.


CONCLUSIONS
A diet containing 0.6-0.8 g of protein/kg IBW/day is safe and, when combined with keto acids, is associated with an improved preservation of RRF in relatively new PD patients without significant malnutrition or inflammation.
Jiang
Na
N
Renal Division, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai Center for Peritoneal DialysisResearch, Shanghai, People's Republic of China.
Qian
Jiaqi
J
Sun
Weilan
W
Lin
Aiwu
A
Cao
Liou
L
Wang
Qin
Q
Ni
Zhaohui
Z
Wan
Yanping
Y
Linholm
Bengt
B
Axelsson
Jonas
J
Yao
Qiang
Q
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004044:Dietary Proteins / Q000008:administration & dosage*; D019587:Dietary Supplements; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007651:Keto Acids / Q000378:metabolism*; D007676:Kidney Failure, Chronic / Q000178:diet therapy* / Q000378:metabolism*; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000378:metabolism; D010530:Peritoneal Dialysis / Q000379:methods*; D011446:Prospective Studies; D014018:Tissue Distribution; D055815:Young Adult
D004044:Dietary Proteins; D007651:Keto Acids; D009584:Nitrogen