title: Effect of increased protein intake on renal acid load and renal hemodynamic responses.
abstract: Increased protein intake versus maltodextrin intake for 4 weeks lowers blood pressure. Concerns exist that high-protein diets reduce renal function. Effects of acute and 4-week protein intake versus maltodextrin intake on renal acid load, glomerular filtration rate and related parameters were compared in this study. Seventy-nine overweight individuals with untreated elevated blood pressure and normal kidney function were randomized to consume a mix of protein isolates (60 g/day) or maltodextrin (60 g/day) for 4 weeks in energy balance. Twenty-four-hour urinary potential renal acid load (uPRAL) was compared between groups. A subgroup (maltodextrin N = 27, protein mix N = 25) participated in extra test days investigating fasting levels and postprandial effects of meals supplemented with a moderate protein- or maltodextrin-load on glomerular filtration rate, effective renal plasma flow, plasma renin, aldosterone, pH, and bicarbonate. uPRAL was significantly higher in the protein group after 4 weeks (P ≤ 0.001). Postprandial filtration fraction decreased further after the protein-supplemented breakfast than after the maltodextrin-supplemented breakfast after 4 weeks of supplementation (P ≤ 0.001). Fasting and postprandial levels of glomerular filtration rate, effective renal plasma flow, renin, aldosterone, angiotensin-converting enzyme, pH and bicarbonate did not differ between groups. In conclusion, 4 weeks on an increased protein diet (25% of energy intake) increased renal acid load, but did not affect renal function. Postprandial changes, except for filtration fraction, also did not differ between groups. These data suggest that a moderate increase in protein intake by consumption of a protein mix for 4 weeks causes no (undesirable) effects on kidney function in overweight and obese individuals with normal kidney function.
authors.affiliation: Top Institute Food and Nutrition, Wageningen, The Netherlands Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism Maastricht University, Maastricht, The Netherlands.
authors.forename: Karianna F M
authors.initials: KF
authors.lastname: Teunissen-Beekman
authors.affiliation: Top Institute Food and Nutrition, Wageningen, The Netherlands Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism Maastricht University, Maastricht, The Netherlands.
authors.forename: Janneke
authors.initials: J
authors.lastname: Dopheide
authors.affiliation: Top Institute Food and Nutrition, Wageningen, The Netherlands Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Geleijnse
authors.affiliation: Top Institute Food and Nutrition, Wageningen, The Netherlands Department of Medicine, University Medical Center Groningen and University of Groningen, Groningen, The Netherlands.
authors.forename: Stephan J L
authors.initials: SJ
authors.lastname: Bakker
authors.affiliation: Top Institute Food and Nutrition, Wageningen, The Netherlands.
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Brink
authors.affiliation: Department of Medicine, Maastricht University Medical Center and Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands.
authors.forename: Peter W
authors.initials: PW
authors.lastname: de Leeuw
authors.affiliation: Top Institute Food and Nutrition, Wageningen, The Netherlands Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism Maastricht University, Maastricht, The Netherlands m.vanbaak@maastrichtuniversity.nl.
authors.forename: Marleen A
authors.initials: MA
authors.lastname: van Baak
mesh_terms: D000136:Acid-Base Equilibrium / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism*; D004311:Double-Blind Method; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy / Q000378:metabolism; D011134:Polysaccharides / Q000008:administration & dosage; D012079:Renal Circulation / Q000502:physiology*
chemical_list: D004044:Dietary Proteins; D011134:Polysaccharides; C008315:maltodextrin
keywords: Acid load; carbohydrate; glomerular filtration rate; kidney; protein