Kidney Health and High Protein — Separating Myth from Evidence

The “high protein damages kidneys” claim is one of the most persistent myths in nutrition. Here’s what the data actually says.

The concern originates from the observation that high protein intake increases glomerular filtration rate (GFR) and renal workload. In patients with pre-existing chronic kidney disease (CKD), protein restriction is indeed recommended to slow disease progression. The error was extrapolating this clinical recommendation to healthy populations.

Devries et al. (2018) published a meta-analysis in the Journal of Nutrition examining the effects of higher versus lower protein intakes on kidney function in healthy adults. Across 28 trials, higher protein intakes increased GFR (as expected, reflecting normal physiological adaptation) but did not cause kidney damage or progressive decline in function.

Martin et al. (2005) studied the effects of a high-protein diet (2.8 g/kg/day) over 7 days in resistance-trained men and found no adverse effects on any measure of kidney function. Van Elswyk et al. (2018) conducted a systematic review and concluded that evidence does not support an association between high protein intake and impaired renal function in healthy individuals.

The distinction is critical: protein restriction is appropriate for people with diagnosed kidney disease. For people with healthy kidneys, there is no evidence that high protein intakes (up to 2.0–2.5 g/kg/day) cause kidney damage.

If you have concerns about kidney function, get tested — serum creatinine and estimated GFR are routine blood tests. But don’t restrict protein based on a myth that has been repeatedly contradicted by the evidence.

References

1. Devries MC, Sithamparapillai A, Brimble KS, et al. Changes in kidney function do not differ between healthy adults consuming higher- compared with lower- or normal-protein diets: a systematic review and meta-analysis. J Nutr. 2018;148(11):1760-1775. PubMed
2. Martin WF, Armstrong LE, Rodriguez NR. Dietary protein intake and renal function. Nutr Metab (Lond). 2005;2:25. PubMed