Effects of synbiotic supplementation on microbiota-derived protein-bound uremic toxins, systemic inflammation, and biochemical parameters in patients on hemodialysis: A double-blind, placebo-controlled, randomized clinical trial.

Objectives: The generation of key nephrovascular protein-bound uremic toxins, indoxyl sulfate and phenol, in hemodialysis (HD) patients is attributed to the dysbiotic gut microbiota. The aim of this study was to investigate the effects of synbiotic supplementation on serum levels of indoxyl sulfate, phenol, inflammation, and biochemical parameters in HD patients.

Methods: Forty-two HD patients (synbiotic group: n = 21; placebo group: n = 21) were analyzed in this randomized, double-blind, placebo-controlled study. During a 2-mo intervention, the synbiotic group received two synbiotic capsules daily, between the main meals, whereas the placebo group received maltodextrin as the placebo. Blood pressure, uremic factors, and biochemical parameters were assessed before the start and after the end of the study.

Results: After adjustment for potential confounders, there was no significant effect of synbiotic on serum levels of urea, creatinine, liver enzymes, high-sensitivity C-reactive protein, sodium, potassium, phosphorus, blood pressure, or albumin in the treatment group compared with the placebo group. A significant increase in indoxyl sulfate and parathyroid hormone levels were observed only in the treatment group. However, between-group analyses were not significant. Compared with baseline values, phenol levels were decreased in both groups (P≤001), with no significant between-group difference.

Conclusions: Synbiotic supplementation might increase indoxyl sulfate and parathyroid hormone levels in HD patients.