Abstract
- Background
While numerous individual systematic reviews and meta-analyses have evaluated the potential of curcumin—the primary bioactive polyphenol derived from Curcuma longa (turmeric)—to reduce circulating inflammatory biomarkers, findings across existing literature remain inconsistent due to varying methodologies and cohort characteristics. Chronic low-grade systemic inflammation is a primary pathological contributor to a broad array of chronic non-communicable diseases, including metabolic syndrome, cardiovascular pathologies, and autoimmune disorders, necessitating precise quantitative syntheses of therapeutic interventions. This umbrella meta-analysis was designed to rigorously aggregate existing meta-analytic evidence, resolve inconsistencies, and provide a definitive, high-level estimate of the overall therapeutic effects of curcumin supplementation on key systemic inflammatory biomarkers.
- Methods
A comprehensive, systematic literature search was conducted across major international electronic databases—including PubMed, Scopus, Embase, Web of Science, and Google Scholar—from inception up to March 20, 2022. Eligible studies comprised meta-analyses of randomized controlled trials investigating the impact of curcumin supplementation on circulating inflammatory biomarkers, reporting corresponding effect sizes (ES) and confidence intervals (CI). A random-effects model was applied to calculate pooled summary effect sizes, while heterogeneity was evaluated using the $I^2$ statistic. The overall certainty of the synthesized evidence was formally assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework. Evaluated primary endpoints encompassed circulating concentrations of C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-$\alpha$).
- Results
Synthesis of ten meta-analyses comprising a cumulative total of 5,870 participants demonstrated statistically significant anti-inflammatory efficacy following curcumin supplementation:
Reduction of C-Reactive Protein (CRP): Curcumin supplementation induced a statistically significant decrease in circulating CRP levels (ES = -0.74; 95% CI: -1.11, -0.37; $P < 0.001$; $I^2 = 62.1\%$, $P = 0.015$).
Suppression of Interleukin-6 (IL-6): A marked and significant reduction in circulating IL-6 concentrations was observed across pooled cohorts (ES = -1.07; 95% CI: -1.71, -0.44; $P < 0.001$; $I^2 = 75.6\%$, $P < 0.001$).
Attenuation of Tumor Necressor Factor-$\alpha$ (TNF-$\alpha$): Analysis revealed a profound and statistically significant decrease in TNF-$\alpha$ levels following intervention (ES = -1.92; 95% CI: -2.64, -1.19; $P < 0.001$; $I^2 = 18.1\%$, $P = 0.296$).
Subgroup & Moderator Insights: Greater magnitude effects on CRP and TNF-$\alpha$ reductions were notably more pronounced in clinical trials involving participants with a mean age exceeding 45 years and cumulative sample sizes greater than 300 participants.
The intervention maintained a high degree of safety and tolerability across evaluated clinical trials.
- Conclusions
This umbrella meta-analysis confirms that curcumin supplementation significantly reduces key systemic inflammatory biomarkers, specifically C-reactive protein, interleukin-6, and tumor necrosis factor-alpha. These robust findings support the clinical positioning of curcumin as a promising, safe, and effective adjunctive botanical therapeutic approach for the comprehensive management of chronic human diseases characterized by elevated systemic inflammation.
https://pmc.ncbi.nlm.nih.gov/articles/PMC9870680/