Effects of isoflavones on bone turnover markers in peritoneal dialysis patients: a randomized controlled trial

Purpose The aim of this study was to investigate the effects of soy isoflavones on serum markers of bone formation and resorption in peritoneal dialysis (PD) patients. Methods In this randomized, double-blind, placebo-controlled trial, 40 PD patients were randomly assigned to either the soy isoflavone or the placebo group. The patients in the soy isoflavone group received 100 mg soy isoflavones daily for 8 weeks, whereas the placebo group received corresponding placebos. At baseline and the end of the 8th week, 7 ml of blood was obtained from each patient after a 12- to 14-h fast and serum concentrations of bone formation markers (osteocalcin and bone alkaline phosphatase), bone resorption markers [N-telopeptide and receptor activator of nuclear factor kappa B ligand (RANKL)], and osteoprotegerin as an inhibitor of bone resorption were measured. Results Serum N-telopeptide concentration decreased significantly up to 27% in the soy isoflavone group at the end of week 8 compared to baseline ( P = 0.003). Also, serum RANKL concentration reduced significantly up to 17% in the soy isoflavone group at the end of week 8 compared to baseline ( P = 0.03). These bone resorption markers did not significantly change in the placebo group during the study. There were no significant differences between the two groups in mean changes of serum osteocalcin, bone alkaline phosphatase, and osteoprotegerin. Conclusion This study indicates that daily administration of 100 mg soy isoflavone supplement to PD patients reduces serum N-telopeptide and RANKL which are two bone resorption markers. ClinicalTrials.gov NCT03773029, 2018.