evaluating the impact of vitamin d supplementation on serum leptin levels: a meta-analysis of randomized controlled trials

Background and objectives: vitamin d, crucial for bone health and calcium homeostasis, also impacts metabolic processes and endocrine functions. it may influence leptin, a key hormone regulating energy balance. this meta-analysis evaluates the effect of vitamin d supplementation on serum leptin concentrations, addressing inconsistencies and exploring its potential role in metabolic health.materials and methods: this review examined supplementation with vitamin d, alone or with calcium, as an intervention for its effects on serum leptin concentrations. following prisma guidelines, a comprehensive search of electronic databases up to march 2024 identified eligible trials. eleven randomized clinical trials were included, assessing vitamin d supplementation versus placebo or control. the meta-analysis, registered in prospero (www.crd.york.ac.uk/ prospero/ crd42020177472), used stata for statistical analysis, with outcomes reported as mean differences (md) and 95% confidence intervals (cis).results: initially, 503 studies were identified, with 366 excluded after screening. ultimately, 11 studies with 819 participants were included. trials varied in vitamin d dosage, frequency, and whether calcium was included. pooled analysis found no significant effect of vitamin d on leptin concentrations (md: -0.13, 95% ci -1.12 to 0.87). subgroup analyses showed no differences based on intervention duration or calcium inclusion.conclusions: our meta-analysis demonstrated that vitamin d supplementation does not significantly affect serum leptin levels, adding to the existing evidence on vitamin d metabolic roles. further research is crucial to unravel the interaction between vitamin d and adipokines like leptin, given widespread vitamin d deficiency and its metabolic implications.