Effect of short-term high-protein compared with normal-protein diets on renal hemodynamics and associated variables in healthy young men.
BACKGROUND
High-protein diets are effective for weight reduction; however, little is known about the potential adverse renal effects of such diets.


OBJECTIVE
The aim of our study was to compare the effect of a high-protein (HP) with a normal-protein (NP) diet on renal hemodynamics and selected clinical-chemical factors.


METHODS
We prospectively studied the effect of an HP diet (2.4 g x kg(-1) x d(-1)) with that of an NP diet (1.2 g x kg(-1) x d(-1)) on the glomerular filtration rate (assessed on the basis of sinistrin-an inulin analog-clearance) and renal plasma flow (para-aminohippuric acid clearance) by using the constant infusion technique. Filtration fraction and renal vascular resistance were calculated. Twenty-four healthy young men followed the 2 diet protocols for 7 d each in a crossover design. They were individually advised by a dietitian to achieve the planned protein intake by selecting normal foods under isocaloric conditions. Serum and urinary variables and renal hemodynamics were measured on day 7 of both diets.


RESULTS
The glomerular filtration rate (NP: 125 +/- 5 mL/min; HP: 141 +/- 8 mL/min; P < 0.001) and filtration fraction (NP: 23 +/- 5%; HP: 28 +/- 5%; P < 0.05) increased significantly with the HP diet. Renal plasma flow was not significantly different between the HP (496 +/- 25 mL/min) and NP (507 +/- 18 mL/min) phases. Renal vascular resistance was not significantly different between the NP (94 +/- 6 mm Hg x mL(-1) x min(-1)) and HP (99 +/- 8 mm Hg x mL(-1) x min(-1)) phases. Blood urea nitrogen, serum uric acid, glucagon, natriuresis, urinary albumin, and urea excretion increased significantly with the HP diet.


CONCLUSIONS
A short-term HP diet alters renal hemodynamics and renal excretion of uric acid, sodium, and albumin. More attention should be paid to the potential adverse renal effects of HP diets.
Frank
Helga
H
Klinikum rechts der Isar, Technical University Munich, Munich, Germany. helga.frank@lrz.tum.de
Graf
Julia
J
Graf
Juliane
J
Amann-Gassner
Ulrike
U
Bratke
Renate
R
Daniel
Hannelore
H
Heemann
Uwe
U
Hauner
Hans
H
D000328:Adult; D000419:Albuminuria / Q000209:etiology; D001794:Blood Pressure; D018592:Cross-Over Studies; D004044:Dietary Proteins / Q000008:administration & dosage*; D005919:Glomerular Filtration Rate; D006439:Hemodynamics; D006801:Humans; D008297:Male; D011446:Prospective Studies; D017595:Renal Plasma Flow; D014527:Uric Acid / Q000652:urine; D014655:Vascular Resistance
D004044:Dietary Proteins; D014527:Uric Acid