Inulin-type prebiotics reduce serum uric acid levels via gut microbiota modulation: a randomized, controlled crossover trial in peritoneal dialysis patients

Purpose Increased levels of uric acid (UA), which is mainly excreted through the kidneys, are independently associated with higher mortality in end-stage renal disease (ESRD) patients. The uricolysis of gut microbiota plays an important role in extrarenal excretion of UA. This study aimed to examine the effect of inulin-type prebiotics (a type of fermentable dietary fiber) on intestinal microbiota modulation and serum UA levels in ESRD patients. Methods Continuous ambulatory peritoneal dialysis (CAPD) patients were recruited to a randomized, double-blind, placebo-controlled crossover trial of 12-week inulin-type prebiotics. Participants were visited before and after treatment with prebiotics or placebo. Serum UA levels, dietary purine intake, serum xanthine oxidase (XO) activity, daily renal excretion of UA, and fecal UA degradation capability were measured at each visit. Fecal metagenomic analysis was conducted to assess microbial composition and function. Results Sixteen participants (mean age = 37 y; 10 men and 6 women) completed the trial, and 64 specimens were analyzed. The average concentration of serum UA decreased by approximately 10% in the prebiotic intervention group in comparison to the placebo group (p = 0.047) without an increase in daily renal excretion of UA via urine and dialysate. There were no significant changes in purine intake or activity of XO. Notably, enhanced fecal UA degradation was observed after prebiotic intervention (p= 0.041), and the ratio of Firmicutes/Bacteroidetes, which was positively associated with fecal UA degradation, increased in the prebiotic period (p = 0.032). Furthermore, prebiotics enriched purine-degrading species in the gut microbiota, including unclassified_o_Clostridiales, Clostridium sp. CAG:7, Clostridium sp. FS41, Clostridium citroniae, Anaerostipes caccae, and Clostridium botulinum. Conclusions Inulin-type prebiotics is a promising therapeutic candidate to reduce serum UA levels in renal failure patients, and this urate-lowering effect could possibly be attributed to intestinal microbial degradation of UA.

Automated summary

The study showed that inulin-type prebiotics can significantly decrease serum UA levels in ESRD patients, possibly through intestinal microbial degradation of UA. In addition, prebiotics can also promote an increase in purine-degrading species in the gut microbiota.