Gut microbiota alteration in CKD: From toxicity mechanisms to supplementation

Chronic Kidney Disease (CKD) refers to progressive and irreversible kidney function loss; it is currently an important health problem due to its high social costs. Decreased Glomerular Filtration Rate (GFR) causes accumulation of Uremic Toxins (UT) that must be excreted by the kidney, increasing their serum concentrations, toxicity, and hence disease progression. Dysbiosis is the alteration in the composition and structure of the intestinal microbiota and is related to systemic inflammation. Patients with CKD present biochemical changes at the intestinal level that cause dysbiosis, altering the kidney-gut axis, which is implicated in the higher production of UT. Evidence suggests an association between UT and cardiovascular risk in CKD, and different mechanisms are involved in each of them. Modulation of the gut microbiota by specific nutrients is a new strategy for the nutritional approach to CKD. Novel strategies based on the use of probiotics and prebiotics aim to reduce the synthesis and accumulation of UTs to reduce disease progression; however, with current evidence, the effect and benefit of supplementation cannot be concluded, so more research in humans is needed to identify useful bacterial strains and doses to obtain beneficial effects in CKD patients.