en Nutrition Nutrition Review Review <span style="font-size:10pt"><span style="line-height:115%"><span style="tab-stops:409.5pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b><span style="font-size:11.0pt"><span style="line-height:115%">Background and Objectives: </span></span></b>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.<span style="font-size:11.0pt"><span style="line-height:115%"></span></span></span></span></span></span></span><br> <span style="font-size:10pt"><span style="line-height:115%"><span style="tab-stops:409.5pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b><span style="font-size:11.0pt"><span style="line-height:115%">Materials and Methods: </span></span></b>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).<span style="font-size:11.0pt"><span style="line-height:115%"></span></span></span></span></span></span></span><br> <span style="font-size:10pt"><span style="line-height:115%"><span style="tab-stops:409.5pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b><span style="font-size:11.0pt"><span style="line-height:115%">Results: </span></span></b>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.<span style="font-size:11.0pt"><span style="line-height:115%"></span></span></span></span></span></span></span><br> <span style="font-size:10pt"><span style="line-height:115%"><span style="tab-stops:409.5pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b><span style="font-size:11.0pt"><span style="line-height:115%">Conclusions: </span></span></b>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.<span style="font-size:11.0pt"><span style="line-height:115%"></span></span></span></span></span></span></span> Vitamin D, Leptin, Meta-analysis 31 38 http://nfsr.sbmu.ac.ir/browse.php?a_code=A-10-38-8&slc_lang=en&sid=1 Bahareh Nikooyeh nikooyeh11024@yahoo.com 10031947532846006909 10031947532846006909 Yes Department of Nutrition Research, National Nutrition and Food Technology Research Institute and Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mohammad Esmail Motlagh motlagh-me@ajums.ac.ir 10031947532846006910 10031947532846006910 No Department of Pediatrics, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Tirang Neyestani neytr@yahoo.com 10031947532846006911 10031947532846006911 No Department of Nutrition Research, National Nutrition and Food Technology Research Institute and Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran