Can Higher Protein Diets Support Kidney Health — even in Chronic Kidney Disease?

Breaking Nutrition Science: Protein and Kidney Health

For decades, the fear of protein damaging kidney function has shaped dietary guidelines for both the general population and those with chronic kidney disease (CKD). But a groundbreaking review (PMID: 30383278; PMC Article) is challenging this outdated dogma and rewriting what we know about the relationship between protein and kidney health.

Where did the concern come from?

The fear of protein “overloading” the kidneys dates back to the 1980s, when it was hypothesized that processing large amounts of protein could lead to a progressive decline in kidney function. This notion stuck around, influencing how we view protein intake for over 50 years.

But a meta-analysis published in the Journal of Nutrition reviewed more than two dozen studies involving over 1,300 participants and found no evidence to support this hypothesis. The research examined how low, moderate, and high-protein diets affect kidney function, specifically glomerular filtration rate (GFR)—a key measure of how well the kidneys filter blood.

What the Study Found:

For context, the high protein diet of this study was defined as either 1.5g of protein per kg of body weight or at least 100g of protein per day. This roughly equated to about 20% of daily calories coming from protein.

In both healthy individuals and those with CKD (outside of stages 4-5):

Higher Protein Intake Was Safe: Protein did NOT impair kidney function, even with sustained higher intake.
Glomerular Filtration Rate (GFR): While high-protein diets can temporarily increase GFR, this effect is adaptive and not harmful.
Protein Showed Protective Effects: Dietary protein may actually support kidney health by reducing inflammation and improving overall metabolic markers.
Key Context for CKD: While protein restrictions may be necessary for advanced CKD (stages 4-5), early-stage CKD patients may benefit from re-evaluating their protein needs.

Why This Matters:

1️⃣ For Healthy Individuals: This study confirms what many experts have argued—protein does NOT harm healthy kidneys. In fact, it’s crucial for muscle maintenance, healthy aging, and metabolic health.

2️⃣ For CKD Patients: Blanket protein restrictions may not only be unnecessary for early CKD but could be counterproductive. A nuanced approach is essential.

3️⃣ Debunking Myths: The belief that protein overworks the kidneys and causes damage stems from outdated theories and has been disproven in numerous studies, now further validated by this review. However, there is always more that we can uncover in the future, and we must stay curious about emerging data.

As Stuart Phillips, professor of kinesiology at McMaster University and senior author of the study, states:

“Higher protein diets cause kidney disease—it’s a concept that’s been around for 50 years, but the evidence shows the contrary is true: higher protein increases, not decreases, kidney function.”

Michaela Devries-Aboud, lead author and assistant professor at the University of Waterloo, emphasizes the implications:

“With these findings, we have shown that a higher protein diet is safe. It should be viewed as an important tool for muscle health across an entire lifespan.”

Protein’s Role in Healthy Aging

Protein is more than a macronutrient—it’s a cornerstone of longevity. From preserving muscle mass and bone density to supporting metabolic and immune function, adequate protein intake is vital at every stage of life. This study reinforces its role as not just safe but protective for multiple systems of the body.

The Takeaway:

It’s time to squash the fear around protein and embrace its benefits. For those with CKD (early stages) or healthy kidneys, meeting protein needs may promote better health outcomes without compromising kidney function. With that being said, for those with CKD, be sure to consult with your nephrologist before making changes based on information you come across on the internet 😉.

If you’ve been hesitant about eating protein due to kidney concerns, consider re-evaluating this with guidance from a knowledgeable practitioner. Nutrition science is evolving, and so should our approach!

💬 What do you think of this shift in perspective? What are your thoughts on this meta-analysis?