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This Article Full Text (Publish Ahead of Print[PDF]) All Versions of this Article: 90/6/1509    most recent ajcn.2009.27601v1 Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Frank, H. Articles by Hauner, H. PubMed PubMed Citation Articles by Frank, H. Articles by Hauner, H. Agricola Articles by Frank, H. Articles by Hauner, H.

Effect of short-term high-protein compared with normal-protein diets on renal hemodynamics and associated variables in healthy young men^1,2,3

¹ From Nephrology, Klinikum rechts der Isar (HF, RB, and UH), the Else Kroener-Fresenius Center for Nutritional Medicine (JG, UA-G, and HH), and the Molecular Nutrition Unit (HD), Technical University Munich, Munich, Germany.

² Supported by Else Kröner Fresenius-Stiftung, Bad Homburg, Germany.

³ Address correspondence to H Frank, Nephrology Department, Klinikum rechts der Isar, Technical University Munich, Ismaninger Strasse 22, 81675 Munich, Germany. E-mail: helga.frank{at}lrz.tum.de.

ABSTRACT

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.

Design: We prospectively studied the effect of an HP diet (2.4 g · kg^–1 · d^–1) with that of an NP diet (1.2 g · kg^–1 · 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 · mL^–1 · min^–1) and HP (99 ± 8 mm Hg · mL^–1 · 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.

Received for publication February 8, 2009. Accepted for publication September 3, 2009.