Impact of vitamin D supplementation on the outcomes of kidney transplant recipients: a systematic review and meta-analysis

RATIONALE & OBJECTIVE: A high prevalence of vitamin D deficiency and insufficiency has been documented among individuals who have undergone kidney transplantation. The efficacy of post-transplantation vitamin D therapy remains inconclusive when examined through isolated studies. Therefore, a meta-analytic approach was employed to consolidate current literature and assess the influence of vitamin D supplementation on recipient outcomes following renal transplantation. SELECTION CRITERIA FOR STUDIES: Included were randomized controlled trials and prospective cohort studies related to kidney transplantation, as well as research examining the impact of regular vitamin D supplementation on outcomes following kidney transplantation. RESULTS: 8 studies ultimately satisfied selection criteria for this review. The temporal scope of included studies stretched from 2005 to 2025, encompassing patient populations between 79 and 536 recipients per investigation. Post-baseline surveillance periods diverged substantially, measuring 12 through 24 months. Vitamin D was administered at daily doses between 800 IU and 7000 IU. Supplementation produced significant elevation in 25(OH)D concentrations. A downward trend in parathyroid hormone levels was observed following vitamin D supplementation, though this reduction did not reach statistical significance. Notably, this was achieved safely without provoking hypercalcemia. Post-operative femoral neck bone mineral density T-score additionally showed improvement with vitamin D intervention. CONCLUSION: Post-transplant nutritional vitamin D supplementation increased serum 25(OH)D levels and improved femoral neck bone mineral density t-score in kidney transplant recipients. A downward trend in parathyroid hormone was observed but did not reach statistical significance. Whether vitamin D supplementation improves post-transplant bone disease remains uncertain and requires further investigation. REGISTRATION: Registered at PROSPERO with identification number CRD420251009160.