Fermentable carbohydrate supplementation alters nitrogen excretion in chronic renal failure.
BACKGROUND
Considerable attention has been given to the impact of nutrition on kidney disease. Most dietary attempts to treat chronic renal failure (CRF) and to decrease uremia use a protein restriction. An alternative dietetic approach based on fermentable carbohydrate (FC) supplementation of the diet could lead to the same urea-lowering effect by increasing urea nitrogen (N) excretion in stool, with a concomitant decrease of the total N quantity excreted in urine.


METHODS
In the present prospective study, the impact of FC (40 g/d) on uremia and on N excretion routes was investigated during 5 weeks in nine CRF patients in the presence of a moderated restrictive protein diet (0.8 g/kg/d). Patients were their own controls and were treated by the cross-over method after randomization (5 weeks with FC versus 5 weeks without FC).


RESULTS
Feeding FC significantly increased the quantity of N excreted in stool from 2.1 +/- 0.8 to 3.2 +/- 1.1 g/d (+51%) (P < .01) and decreased, in parallel, the urinary N excretion from 9.4 +/- 1.7 to 8.3 +/- 1.4 g/d (-12%) (P < .01). The total N quantities excreted by the two routes were unchanged by the FC, which shows that the FC was efficient to shift N excretion from the urinary route toward the digestive route. As a result of the increase of urea transfer into the colon, the plasma urea concentration was significantly decreased from 26.1 +/- 8.7 to 20.2 +/- 8.2 mmol/L (-23%) (P < .05).


CONCLUSIONS
These results show the same beneficial effects in CRF as those obtained with a restrictive protein diet without its nutritional drawbacks. This should be confirmed by other prospective works over a longer duration and a larger number of patients to study the effects of FC on CRF progression and on CRF terminal stage tolerance.
Younes
Hassan
H
Department of Nephrology, Hotel Dieu, CHU Clermont-Ferrand, France. hyounes@chu-clermontferrand.fr
Egret
Nadine
N
Hadj-Abdelkader
Mohamed
M
Rémésy
Christian
C
Demigné
Christian
C
Gueret
Claudine
C
Deteix
Patrice
P
Alphonse
Jean-Claude
JC
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000886:Anthropometry; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004043:Dietary Fiber / Q000032:analysis; D004044:Dietary Proteins / Q000008:administration & dosage; D019587:Dietary Supplements; D002149:Energy Intake; D005243:Feces / Q000737:chemistry; D005260:Female; D005285:Fermentation; D006801:Humans; D007676:Kidney Failure, Chronic / Q000378:metabolism / Q000628:therapy* / Q000652:urine; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000032:analysis* / Q000652:urine; D009752:Nutritional Status; D010349:Patient Compliance; D011446:Prospective Studies
D004040:Dietary Carbohydrates; D004043:Dietary Fiber; D004044:Dietary Proteins; D009584:Nitrogen