Rethinking protein choices: the association between the isocaloric substitution of dietary protein sources and dietary acid load in hemodialysis patients: a cross-sectional study

Abstract

Background Hemodialysis (HD) patients experience high morbidity due to metabolic acidosis and malnutrition. Dietary acid load (DAL), largely determined by protein source, is a key modifiable factor in acid-base balance. However, the relationship between protein source substitutions and DAL, considering nutritional status, remains unclear. We investigated associations between exchanging dietary protein sources and DAL in HD patients. Methods This multicenter cross-sectional study enrolled 307 maintenance HD patients. Dietary intake was assessed using a validated 168-item semi-quantitative food frequency questionnaire, and serum albumin was measured from blood samples. Isocaloric substitutions of 1 g/day protein from one source for another were evaluated using generalized linear models with simultaneous inclusion of both protein sources, adjusted for total energy intake and relevant confounders. Results Isocaloric substitution of red/processed meat with dairy, legume, or nut protein was significantly associated with increased odds of higher DAL. Conversely, replacing dairy protein with red/processed or white meat, as well as exchanging legume or nut protein for red/processed or white meat, was associated with reduced odds of higher DAL. These associations were markedly modified by nutritional status assessed by serum albumin. In patients with lower albumin levels (< 3.83 g/dL), substitutions involving red/processed meat replacement with plant-based proteins showed stronger associations with Potential renal acid load (PRAL), an estimate of the renal acid excretory requirement imposed by diet, with the most pronounced protective association observed when nut protein was replaced with red/processed meat. In patients with higher albumin levels (>= 3.84 g/dL), replacement of white protein with dairy, legume, or nut protein uniformly increased PRAL odds, while substituting legume or nut protein with red/processed or white meat consistently exerted a protective association against elevated dietary acid load. Conclusion Protein source substitutions are independently associated with DAL in hemodialysis patients, with effect directions and magnitudes varying by specific food combinations and substantially modified by nutritional status. These findings support personalized dietary strategies integrating both protein source selection and individual patient characteristics for optimized acid-base management in this high-risk population.