Effect of increased protein intake on renal acid load and renal hemodynamic responses

Physiol Rep. 2016 Mar;4(5):e12687. doi: 10.14814/phy2.12687.

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.

Keywords: Acid load; carbohydrate; glomerular filtration rate; kidney; protein.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acid-Base Equilibrium / physiology*
  • Blood Pressure / physiology
  • Dietary Proteins / administration & dosage*
  • Dietary Proteins / metabolism*
  • Double-Blind Method
  • Female
  • Glomerular Filtration Rate / physiology
  • Hemodynamics / physiology*
  • Humans
  • Kidney / metabolism*
  • Male
  • Middle Aged
  • Obesity / diet therapy
  • Obesity / metabolism
  • Polysaccharides / administration & dosage
  • Renal Circulation / physiology*

Substances

  • Dietary Proteins
  • Polysaccharides
  • maltodextrin