Short-term effects of therapeutic diet on bone turnover markers in hemodialysis patients: an exploratory analysis of a randomized crossover trial

Bone turnover abnormalities are common in patients undergoing hemodialysis and contribute to fracture, vascular calcification, and mortality. Although therapeutic diets targeting phosphate balance improve mineral metabolism, their short-term effects on bone turnover remain unclear. In this post hoc analysis of a randomized crossover trial, 30 adults undergoing thrice-weekly hemodialysis received either a 7-day dialysis-specific therapeutic diet or their usual diet. The therapeutic diet emphasized a lower phosphorus-to-protein ratio, higher plant-based content, and increased fiber. Serum bone-specific alkaline phosphatase (BAP), osteocalcin, procollagen type 1 N-terminal propeptide (P1NP), C-terminal telopeptide of type I collagen (CTX), and tartrate-resistant acid phosphatase 5b (TRACP-5b) were assessed at baseline and on days 2, 5, and 7 of each phase. Mixed-effects models assessed associations between dietary phosphorus intake and bone turnover markers. The therapeutic diet significantly increased BAP levels after 7 days (median difference: + 0.8 μg/L, P = 0.02), but did not alter other markers. In multivariate models, a 100 mg reduction in dietary phosphorus intake corresponded to a 0.9% increase in BAP, 2.8% in P1NP, and 1.7% in TRACP-5b. Despite the small sample size and brief intervention, these findings suggest that short-term dietary phosphorus restriction may influence bone formation and resorption markers in hemodialysis patients.