Low-protein diet supplemented with inulin lowers protein-bound toxin levels in patients with stage 3b-5 chronic kidney disease: a randomized controlled study

Objective: this study aimed to evaluate whether low-salt low-protein diet (LPD) supplemented with 10 g of inulin could lower serum toxin levels in patients with chronic kidney disease (CKD), thereby providing evidence for adjusting dietary prescriptions of inhospital patients and outpatient nutrition consultants. Methods: we randomized 54 patients with CKD into two groups. Dietary protein intake compliance was evaluated using a 3-day dietary diary and 24-h urine nitrogen levels. The primary outcomes were indoxyl sulfate (IS) and p-cresyl sulfate (PCS), and secondary outcomes included inflammation marker levels, nutritional status, and renal function. We assessed 89 patients for eligibility, and a total of 45 patients completed the study, including 23 and 22 in the inulin-added and control groups, respectively.Results: PCS values decreased in both groups after intervention: inulin-added group, increment PCS-1.33 (-4.88,-0.63) pg/mL vs. LPD group,-4.7 (-3.78, 3.69) pg/mL (p = 0.058). PCS values reduced from 7.52 to 4.02 pg/mL (p < 0.001) in the inulin-added group (p < 0.001). Moreover, IS decreased from 3.42 (2.53, 6.01) pg/mL to 2.83 (1.67, 4.74) pg/mL after adding inulin; increment IS was-0.64 (-1.48, 0.00) pg/mL, and a significant difference was observed compared with the control group (p = 0.004). The inflammation index decreased after intervention.Conclusion: dietary fiber supplementation may reduce serum IS and PCS levels and modulate their inflammatory status in predialysis CKD patients.