Serum Levels of Vitamins and Trace Elements in Patients with Visceral Leishmaniasis: a Systematic Review and Meta-analysis

Visceral leishmaniasis (VL), a fatal disease prevalent in more than 70 countries, poses significant health challenges, particularly in poor communities with limited access to healthcare. Vitamins and trace elements play a crucial role in immune function and may influence susceptibility to VL. This systematic review and meta-analysis aimed to assess the differences in serum vitamin and trace element levels in VL patients compared to healthy individuals. We conducted an extensive search of databases (PubMed, Embase, and Google Scholar) to identify potentially eligible articles published from inception to June 2023. Data extraction and quality assessment were carried out by two reviewers independently. RevMan software (version 5.4) was used for analysis. Standardized mean difference (SMD) with a confidence interval (CI) of 95% was used to summarize the findings. Ten studies comprising 546 VL patients and 535 controls were included in our study. The findings revealed significantly reduced serum retinol levels in VL patients in comparison to controls (SMD: - 0.67; 95% CI: [- 1.05, - 0.28]; p = 0.0008). Serum zinc levels were also substantially lower in VL patients, regardless of controls recruited from endemic (SMD: - 2.65; 95% CI: [- 3.86, - 1.44]; p < 0.0001) or non-endemic regions (SMD: - 1.99; 95% CI: [- 3.02, - 0.96]; p < 0.0002). However, VL patients exhibited significantly increased serum copper levels compared to controls (SMD: 2.51; 95% CI: [0.70, 4.32]; p = 0.007). Patients with VL had lower serum levels of zinc and retinol and higher levels of copper, indicating a possible role of these micronutrients in influencing VL susceptibility and progression.