Low-protein diet for chronic kidney disease: Evidence, controversies, and practical guidelines

The benefits of a low-protein diet (LPD) in patients with altered kidney function remain controversial. Dietary intake studies are inherently complex and may present numerous biases that must be understood and controlled. Due to these challenges, the scientific evidence in this area remains limited and is subject to dispute. However, there is abundant literature showing that excessive protein intake in these patients is linked to cardiovascular issues, oxidative stress, hyperphosphatemia, bone mineral disease, metabolic acidosis, inflammation, and gut dysbiosis, contributing to kidney damage and other concurrent systemic disorders. An LPD remains a valuable recommendation for non-dialysis chronic kidney disease (CKD) patients if age, nutritional status, and disease complications are carefully considered to ensure optimal outcomes. On the one hand, excessive protein intake may lead to the accumulation of nitrogenous waste products, thereby burdening renal function. On the other hand, overly restrictive protein consumption can lead to muscle mass loss, potentially worsening clinical outcomes and patient prognosis. This narrative review highlights the harmful impact of a high-protein diet on kidney function, particularly for those with preexisting kidney impairment or a predisposition to CKD. It also discusses the importance of an individualized and well-monitored protein intake strategy to balance the benefits of protein restriction with the risks of malnutrition.