Níveis plasmáticos de marcadores inflamatórios e toxinas urêmicas em resposta a ingestão de carne vermelha e bacalhau em indivíduos com doença renal crônica: um ensaio clínico do tipo crossover

Abstract

Introduction: Different sources of animal protein can modulate the production of uremic toxins by the gut microbiota in distinct ways, including indoxyl sulfate (IS), p-cresyl sulfate (p-CS), and indole-3-acetic acid (IAA), as well as influence inflammatory and oxidative stress pathways. Although recent studies have investigated the effects of diets rich in animal-based foods compared to predominantly plant-based diets on various health outcomes, there is still limited evidence regarding the differences between different sources of animal protein and their physiological and metabolic impacts. This gap is particularly relevant in patients with chronic kidney disease (CKD) undergoing hemodialysis (HD), in whom increased protein intake is necessary, making protein quality a potentially determining factor. Objective: To evaluate and compare the effect of red meat and fish intake on plasma concentrations of isopropyl alcohol (IS), p-CS, acetylsalicylic acid (AIA), interleukin-17 (IL-17), interleukin 1β (IL-1β), malondialdehyde (MDA), and carbonylated proteins in individuals with chronic kidney disease (CKD) undergoing hemodialysis (HD). Materials and methods: A crossover clinical trial with a washout period was conducted involving a convenience sample of 14 HD patients treated at the nephrology service of the Pedro Ernesto University Hospital in Rio de Janeiro. Participants were divided into two groups according to dialysis days, receiving a single source of animal protein (red meat or cod) at lunch and dinner for four consecutive days. After this phase, a two-week washout period was performed, followed by a reversal of interventions between the groups. Plasma levels of uremic toxins were analyzed using Reversed-Phase High-Performance Liquid Chromatography. IL-1β and IL-17E levels were quantified using an ELISA assay, and oxidative stress was indirectly assessed through lipid peroxidation (malondialdehyde, MDA) and plasma protein carbonylation. Clinical, dietary, anthropometric, and laboratory data were also analyzed. Results: A total of 14 patients completed the red meat intervention phase [9 men, 5 women; median age: 49 years (IQR=29); body mass index: 26.1 kg/m² (IQR=6.7)], while one patient declined to participate in the fish intervention. No significant differences were observed in plasma concentrations of IS, p-CS, AIA, IL-17E, IL-1β, MDA, or carbonylated proteins after ingestion of red meat or cod, nor were there significant differences between the groups. IL-1β concentration correlated positively with MDA (r=0.74; p=0.002). Conclusion: Short-term intake of red meat or cod did not significantly alter uremic toxins, inflammatory markers, or oxidative stress in hemodialysis patients, suggesting that other factors may influence the levels of these biomarkers. Further studies are needed to investigate different protein sources and refine dietary recommendations for chronic kidney disease patients on hemodialysis.