Melatonin supplementation and pro-inflammatory mediators: a systematic review and meta-analysis of clinical trials.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of clinical trials
PubMed 31679041 · doi:10.1007/s00394-019-02123-0
What was done
A systematic review and random-effects meta-analysis of clinical trials was conducted to evaluate the effect of melatonin supplementation on inflammatory biomarkers (TNF-α, IL-6, and CRP). Databases including PubMed, Scopus, Cochrane Library, Embase, and Google Scholar were searched up to April 2019. Subgroup analysis, sensitivity analysis, and meta-regression were also conducted.
What was found
Thirteen eligible studies with 22 datasets and 749 total participants were analyzed: - Melatonin supplementation significantly decreased TNF-α levels (WMD = -2.24 pg/ml; 95% CI: -3.45 to -1.03; P < 0.001; I² = 96.7%). - Melatonin supplementation significantly decreased IL-6 levels (WMD = -30.25 pg/ml; 95% CI: -41.45 to -19.06; P < 0.001; I² = 99.0%). - Melatonin had a marginal, non-significant effect on CRP levels (WMD = -0.45 mg/L; 95% CI: -0.94 to 0.03; P = 0.06; I² = 96.6%).
Why it matters
This review provides quantitative clinical trial evidence that melatonin can reduce specific circulating pro-inflammatory cytokines, supporting its proposed anti-inflammatory role.
Limits
Statistical heterogeneity across studies was extremely high (I² ≥ 96.6% for all outcomes). Total sample size across 13 trials was small (749 participants). Participant characteristics, clinical conditions, melatonin dosages, intervention durations, and risk of bias are not reported in the abstract.
Cited by
- supports A meta-analysis of randomized controlled trials found that melatonin use is associated with a reduction in TNF-alpha and IL-6 levels.