Low-protein diet adherence and CKD progression during long-term follow-up

BACKGROUND AND HYPOTHESIS: In early chronic kidney disease (CKD), a low-protein diet (LPD) may reduce glomerular hyperfiltration and delay progression; however, long-term studies in middle-income countries are limited. This study evaluates the impact of adherence to an LPD on CKD progression in Brazilian patients. METHODS: 438 patients from a single center in Brazil between 2010 and 2024, comprising 306 patients who adhered to the LPD (<0.8 g/kg/day ± 10%) and 132 who did not adhere (>0.88 g/kg/day), based on calculations from 24-hour dietary recalls. The primary outcome was CKD progression, evaluated by the annual decline rate in estimated glomerular filtration rate (eGFR). Progression was analyzed both as a continuous variable (rate of eGFR decline over time) and by classification into normal decline (0-4.9 mL/min/year) or fast decline (>5 mL/min/year). A linear mixed model was used to evaluate the impact of adherence to an LPD on eGFR decline over time, adjusting for potential confounders. RESULTS: The eGFR was comparable between groups, with adherent participants displaying a mean of 33.58 ± 13.71 mL/min and a mean age of 63.5 ± 13.8 years, and the non-adherent group had a mean of 31.54 ± 13.18 mL/min and 62.9 ± 15.3 years at baseline. Regarding protein intake and eGFR decline classification, no significant differences were observed between the groups. However, in the adjusted analysis, participants who adhered to the LPD had a significantly slower annual decline in eGFR compared to non-adherent individuals. The estimated mean annual change in eGFR was -0.29 mL/min/1.73 m² for adherent participants and -1.40 mL/min/1.73 m² for non-adherent participants. The absolute adjusted difference between groups was 1.10 mL/min/1.73 m² (95% CI: 0.34 to 1.87; p = 0.0048). CONCLUSIONS: The findings support the potential nephroprotective role of LPD adherence in prolonging kidney function, reinforcing the importance of dietary management in CKD treatment.