A recent South Korean study presented at the American Society of Nephrology Kidney Week annual meeting suggests that severely limiting dietary protein may be detrimental to patients with chronic kidney disease (CKD) who do not yet require dialysis.
Protein Restriction Linked to Higher Health Risks
Researchers examined data from 1,861 patients with CKD stages 1 to 5, who were treated at nine tertiary hospitals between 2011 and 2016. The patients were followed for a median period of 9.3 years. To estimate daily protein intake, the researchers used baseline 24-hour urinary urea nitrogen excretion data.
Patients who consumed the least amount of protein, defined as less than 0.6 grams per kilogram of body weight, were found to have a 42% higher risk of experiencing kidney failure that required long-term hemodialysis, peritoneal dialysis, or kidney transplantation, compared to those who consumed the most protein (at least 1.2 g/kg).
Further analysis of secondary endpoints revealed that patients with the lowest protein intake had more than double the risk of all-cause mortality, with a subdistribution hazard ratio of 2.17 and a 95% confidence interval of 1.17-4.03. However, this group did not show a statistically significant increase in major adverse cardiovascular events.
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Importance of Nutritional Status in CKD Management
According to Soo Wan Kim, MD, PhD, of Chonnam National University Medical School in Gwangju, South Korea, and colleagues, whose findings were published in JAMA Network Open, maintaining adequate nutritional status and preventing protein-energy wasting are key aspects of CKD management. The authors emphasized that nephrologists should prioritize preserving nutritional status and muscle mass, in addition to reducing kidney workload.
The biological rationale for restricting protein intake is based on the idea that protein consumption contributes to the production of uremic toxins and metabolic acidosis, which can drive intraglomerular hypertension and accelerate kidney injury. However, the authors suggest that the risks associated with severe protein restriction may outweigh the potential benefits of reducing kidney workload.
In 2024, the KDIGO guidelines were revised to recommend a more moderate protein intake for CKD patients, with a suggested daily intake of approximately 0.8 g/kg for patients with CKD stages 3-5. This recommendation is consistent with the daily protein intake advised for the general population.
Because the study was observational, causality could not be definitively established. The study relied on a single baseline urine collection to estimate protein intake.
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Expert Insights on Protein Intake and CKD Management
George Bonifant, MD, training program director for the nephrology fellowship at Northwell Staten Island University Hospital in New York City, noted that the traditional advice to restrict protein intake in CKD patients has been debated. “Classically, we have recommended anywhere from 60-80% of their total body weight in kg in terms of the mg of proteins that they should take in, which is usually how much fits in the palm of your hand.”
Bonifant warned that patients who consume less than 0.6 g/kg of protein per day are at risk of protein-energy wasting, which can lead to a catabolic state and increased muscle loss. The resulting metabolites, such as urea nitrogen and hydrogen ion, can be detrimental to kidney health and accelerate kidney failure. “In terms of muscle loss, the products that start accumulating in the bloodstream as a result of increased protein muscle metabolism, like urea nitrogen and hydrogen ion, can be detrimental to kidney health,” he said.
Bonifant suggested that CKD patients consider plant-based protein sources, which may be gentler on renal hemodynamics, and limit their intake of foods high in saturated fat, cholesterol, and refined sugars.