Impact of Vitamin D Supplementation on Levels of Serum Cholecalciferol and Cytokines in Individuals with Colorectal Cancer: A Systematic Review and Meta-Analysis of Relevant Clinical Trials

Background: This study assesses the impact of vitamin D supplementation on serum cholecalciferol levels and some cytokines in colorectal cancer (CRC) patients. Methods: We conducted a thorough search for relevant RCTs in PubMed, Scopus, and Google Scholar using appropriate keywords until December 2024. We calculated weighted mean differences (WMDs) and 95% confidence intervals (CIs) through random-effects analysis. Results: Five studies were included. Combining data from four studies showed a significant increase in serum 25 (OH) cholecalciferol levels after supplementation (WMD: 23.72; 95% CI: 12.92, 34.52). However, results from two studies indicated no significant changes in serum CRP (WMD: -2.48; 95% CI: -7.42, 2.46) and IL-6 (WMD: -2.49; 95% CI: -6.89, 1.92) levels. Conversely, TNF-α significantly decreased after administration (WMD: -0.81; 95% CI: -1.18, -0.45). There were no significant changes in anti-inflammatory cytokine IL-10 levels (WMD: 0.29; 95% CI: -0.43, 1.01). Conclusions: This study demonstrates a significant rise in serum 25 (OH) cholecalciferol and a significant decrease in TNF-α, with no notable changes in serum CRP, IL-6, and IL-10 levels in CRC patients after vitamin D treatment.