A Systematic Review of Renal Health in Healthy Individuals Associated with Protein Intake above the US Recommended Daily Allowance in Randomized Controlled Trials and Observational Studies.
Level 1 - systematic review of randomized trials
Systematic review of randomized controlled trials and observational studies
PubMed 30032227 · doi:10.1093/advances/nmy026
What was done
A systematic review evaluated randomized controlled trials (RCTs) and observational studies assessing protein intake at the US Recommended Daily Allowance (0.8 g/kg or 10-15% of energy) versus higher intake (≥20% to <35% of energy, or ≥10% higher than comparison) on kidney function. The review included 26 studies of healthy adults (>18 years old) with or without metabolic risk factors, excluding individuals with chronic kidney disease, end-stage renal disease, cancer, or organ transplants.
What was found
Thirteen RCTs assessed glomerular filtration rate (GFR): 8 reported significantly higher GFR with increased protein intake and 5 reported no significant difference, with all observed values remaining within normal clinical ranges. Increased protein intake had little to no effect on blood markers of kidney function and had no adverse effect on blood pressure. Evidence on kidney stone risk was limited and inconsistent. The abstract reported no specific numerical values or effect sizes for GFR or blood markers.
Why it matters
This review shows that short-term protein intake above the standard RDA up to 35% of daily energy does not impair renal function in healthy adults, with higher GFR reflecting normal physiological adaptation rather than renal damage.
Limits
All 26 included studies were rated at moderate to high risk of bias. Except for two cohort studies, all trials were short-term (<6 months), leaving long-term outcomes unaddressed. Data were insufficient to assess differential effects of plant versus animal protein sources, and stone risk remains inconclusive.
Cited by
- supports There is no scientific evidence that high protein intakes cause kidney damage or reduce bone density in healthy individuals.