Patients with chronic kidney disease (CKD) are advised to avoid high-protein diets to prevent the further decline in kidney functions, yet the impact of such diet modifications on survival outcomes, especially among older adults, remains unclear.¹ A multicohort study was conducted to estimate the associations of total, animal, and plant protein intake with all-cause mortality in older adults with mild or moderate CKD, comparing results to those of older adults without CKD.¹

Older adults typically require additional protein intake due to nutrient shortages.¹ The International PROT-AGE Study Group and ESPEN recommend a daily protein intake of at least 1.0g/kg-1.2g/kg for healthy individuals over 65.^2,3 Nevertheless, high protein intake may promote disease progression in patients with CKD.¹ The current KDIGO guidelines recommend a daily protein intake of 0.8g/kg body weight for adults with stage 3-5 CKD, as high protein intake contributes to increased intraglomerular pressure and glomerular hyperfiltration, leading to glomerulosclerosis and tubulointerstitial injury.⁴

While modifying protein intake can minimize the risk of CKD progression, there is limited evidence of its impact on survival in older patients with CKD.¹ In addition, the role of protein sources has also been of interest.¹ To determine the relationship between protein intake and mortality in older adult patients with mild or moderate CKD and compare the observations with healthy controls, a multicohort study was conducted.¹ The study recruited adults aged ≥60 years from 3 studies: The Swedish National Study on Aging and Care in Kungsholmen (SNAC-K), The Study on Cardiovascular Health, Nutrition and Frailty in Older Adults in Spain (Seniors-ENRICA) 1 and 2.¹ Dietary protein intake was collected using validated methods, including an interviewer-administered electronic dietary history for the Seniors-ENRICA cohorts and a self-administered food frequency questionnaire for the SNAC-K cohort.¹

Between March 2001 and June 2017, data from 14,399 participant observations were analyzed, with one-third having CKD.¹ Among those with CKD, 69.4% were in stage 3A.¹ The study population was followed up for mortality from December 2021 to January 2024.¹ After a maximum follow-up period of 10.0 years, 1,468 participants died, with mortality rates of 17.5% for CKD patients and 6.6% for controls.¹

Analysis of mortality rates in CKD patients showed that higher protein intake is linked to lower mortality.¹ Compared to those with a daily protein intake of 0.8g/kg body weight, those with higher intakes of 1.0g/kg, 1.2g/kg, 1.4g/kg, and 1.6g/kg had reduced risk of death, ranging from 12% to 33%.¹ Specifically, the hazard ratios (HRs) were 0.88 for 1.0g/kg, 0.79 for 1.2g/kg, 0.73 for 1.4g/kg, and 0.67 for 1.6g/kg.¹ The association between mortality and total protein intake per 0.20-g/kg/day increment remained consistent even in patients younger than 75 years.¹

Regarding protein sources, plant protein intake showed a more pronounced, though insignificant, association with reduced mortality risk compared to animal sources.¹ The HRs were 0.80 for plant protein and 0.88 for animal protein, with a p-value for difference in coefficients of 0.34.¹ Age did not significantly impact these associations.¹

Higher total protein intake, measured in 0.20-g/kg/day increments, was associated with lower mortality risk, particularly among healthy controls.¹ The HRs were 0.92 for CKD patients and 0.85 for healthy controls (p_interaction=0.02).¹ Plant protein intake exhibited a stronger association with reduced mortality among healthy controls (HR=0.61) compared to CKD patients (HR=0.80; p_interaction=0.005), while animal protein facilitated comparable risk reductions across both groups.¹

In summary, this multicohort study demonstrated an inverse association between protein intake and mortality in older patients with mild or moderate CKD aged ≥60 years, regardless of protein source.¹ These associations were more pronounced among healthy controls, suggesting that the benefits of higher protein intake may outweigh potential downsides in older patients with mild or moderate CKD.¹ Further investigations are needed to fully understand the impact of protein intake modifications on overall mortality in this patient group.¹