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

• Published in: Physiological reports 2016-03, Vol.4 (5), p.e12687-n/a
• Main Authors: Teunissen‐Beekman, Karianna F. M., Dopheide, Janneke, Geleijnse, Johanna M., Bakker, Stephan J. L., Brink, Elizabeth J., Leeuw, Peter W., Baak, Marleen A.
• Format: Article
• Language: English
• Subjects: Acid load; Acid-Base Equilibrium - physiology; Acids; Adipose Tissue and Obesity; Aldosterone; Angiotensin; Bicarbonates; Blood Pressure; Blood Pressure - physiology; Body weight; Carbohydrate; Dietary Proteins - administration & dosage; Dietary Proteins - metabolism; Dietary supplements; Double-Blind Method; Energy balance; Energy intake; Fasting; Female; Glomerular filtration rate; Glomerular Filtration Rate - physiology; Hemodynamics - physiology; High protein diet; Humans; Kidney; Kidney - metabolism; Kidneys; Laboratory testing; Male; Maltodextrin; Middle Aged; Nutrition; Obesity - diet therapy; Obesity - metabolism; Original Research; Overweight; pH effects; Physiology; Polysaccharides - administration & dosage; Protein; Proteins; Renal Circulation - physiology; Renal Filtration; Renal function; Renin; Sodium
• ISSN: 2051-817X; 2051-817X
• DOI: 10.14814/phy2.12687

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. An increased protein diet (25% of energy intake) for 4 weeks had no effect on fasting renal function despite an increased renal acid load compared to a diet containing 15% of energy in the form of protein. Postprandial changes, except for filtration fraction, also did not differ between diets. These data suggest that consumption of a protein mix for 4 weeks causes no harm for the kidneys.