A new study published in the Journal of Nutrition reports that postintervention glomerular filtration rate (GFR) comparisons indicate that high protein diets result in higher GFRs.
Higher-protein (HP) diets are advocated for several reasons, including mitigation of sarcopenia, but their effects on kidney function are unclear.
“It’s a concept that’s been around for at least 50 years and you hear it all the time: higher protein diets cause kidney disease,” says Stuart Phillips, a professor of kinesiology at McMaster who oversaw the study.
“The fact is, however, that there’s just no evidence to support this hypothesis in fact, the evidence shows the contrary is true: higher protein increases, not decreases, kidney function,” he says.
Michaela C Devries and associates performed a systematic review and meta-analysis to determine the effect of high protein intakes on kidney function in healthy adults.
The researchers analyzed the trials comparing HP (≥1.5 g/kg body weight or ≥20% energy intake or ≥100 g protein/d) with normal- or lower-protein (NLP; ≥5% less energy intake from protein/d compared with HP group) intakes on kidney function. Medline and EMBASE databases were searched. Randomized controlled trials comparing the effects of HP with NLP (>4 d duration) intakes on glomerular filtration rate (GFR) in adults without kidney disease were included.
The data for meta-analysis involved more than 13-hundred participants, including those who were healthy, obese, or had type 2 diabetes and/or high blood pressure. None of the participants were diagnosed with chronic kidney disease and all consumed either a high, moderate or low-protein diet.
A high-protein diet included either 1.5 grams of protein per kilogram of body weight per day, at least 20% of total caloric intake coming from protein or at least 100 grams of protein per day.
The key study findings included are:
- The post-only comparison showed a trivial effect for GFR to be higher after high protein intakes.
- The change in GFR did not differ between interventions.
- There was a linear relation between protein intake and GFR in the post-only comparison but not between protein intake and the change in GFR.
“While there is a breadth of evidence showing the benefits of higher protein consumption, some people are still afraid it could cause kidney damage,” says Michaela Devries-Aboud, lead author of the study and assistant professor of kinesiology at the University of Waterloo, who conducted the analysis as a postdoctoral fellow at McMaster.
“With these findings, we have shown that a higher protein diet is safe. In fact, it should be viewed as an important tool for muscle health across an entire lifespan.”
The study concluded that there is simply no evidence linking a high-protein diet to kidney disease in healthy individuals or those who are at risk of kidney disease due to conditions such as obesity, hypertension or even type 2 diabetes.
For reference log on to http://dx.doi.org/10.1093/jn/nxy197