Dietary fiber may help reduce uremic toxins in patients with chronic kidney disease (CKD), according to a new study.

In a meta-analysis of 10 randomized controlled trials (7 high quality) involving 292 patients, dietary fiber supplements significantly reduced serum levels of indoxyl sulfate, p-cresyl sulfate, blood urea nitrogen, and uric acid by a standardized mean difference of 0.55, 0.47, 0.31, and 0.60, respectively, compared with placebo or another control, Xiao-Hua Wang, PhD, of The First Affiliated Hospital of Soochow University in Suzhou, China, and colleagues reported in the Journal of Renal Nutrition. Indoxyl sulfate reduction was 0.73 greater among supplemented patients on dialysis. Dietary fiber supplements did not significantly reduce serum creatinine in the main analysis, but subgroup analyses indicated a significant 1.04 greater creatinine reduction in supplemented patients without diabetes compared with controls. According to the investigators, individuals with diabetes consume more protein and may have greater creatinine production.

The investigators found no significant differences between fiber supplement dosage (less than or more than 20 g/d) or intervention time (less than or more than 8 weeks), but additional trials are needed. Studied fiber supplements included brans, lignin, cellulose, arabinoxylan, inulin, beta-glucan, guar gum, gum acacia, pectin, psyllium, fructo-oligosaccharides, and resistant starch. Future studies also need to examine total dietary fiber, Dr Wang’s group noted.

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Only 30% of indoxyl sulfate and p-cresyl sulfate, protein-bound uremic toxins produced by intestinal bacteria, are eliminated by hemodialysis, highlighting a need for additional strategies to reduce uremic toxins, according to Dr Wang’s team. These findings can help inform recommendations for clinical practice.


Yang HL, Feng P, Xu Y, Hou YY, Ojo O, Wang XH. The role of dietary fiber supplementation in regulating uremic toxins in patients with chronic kidney disease: a meta-analysis of randomized controlled trials. Published online March 16, 2021. J Ren Nutr. doi:10.1053/j.jrn.2020.11.008