Effects of Maqui Supplementation on Gut Microbiota, Inflammation, and Oxidative Stress in Patients With Chronic Kidney Disease

This is a three-month, randomized, double-blind, placebo-controlled pilot clinical trial designed to evaluate the effects of maqui supplementation in adults with stage 3-4 chronic kidney disease (CKD). The study focuses on biological pathways involved in CKD progression, particularly systemic inflammation, oxidative stress, gut microbiota alterations, and the generation of gut-derived uremic toxins. An exploratory component of the study will examine whether baseline characteristics and responses to the intervention differ according to biological sex. Participants will be randomly assigned to receive either a powdered maqui supplement, providing an amount equivalent to 200 mg of Delphinol, or a maltodextrin placebo once daily for three months. Randomization will be balanced by sex and age and conducted independently from the research team. Study products will be identified using alphanumeric codes to maintain blinding of participants and the clinical and research teams throughout the intervention. Clinical and biological assessments will be performed at baseline and after three months of supplementation. Blood and urine samples will be collected to characterize kidney function, systemic inflammation, oxidative status, and other biochemical parameters related to CKD progression. Stool samples will be collected at the same time points to evaluate gut microbiota composition and gut-derived uremic toxins. Gut microbiota will be characterized through sequencing of the V4 region of the 16S rRNA gene. The study will also assess anthropometric and body composition parameters, blood pressure, and dietary intake. Dietary intake will be evaluated using three-day food records, which will also be used to estimate the Dietary Inflammatory Index. Participants will receive monthly follow-up by a nutritionist during the intervention to assess adherence and identify relevant changes in dietary intake or other factors that could influence the response to supplementation. The study is intended to provide preliminary clinical and biological evidence regarding the potential effects of maqui supplementation in CKD and to generate data for the design of a larger clinical trial. Given the pilot nature of the study, analyses according to biological sex will be considered exploratory.