The effects of ginger supplementation on biomarkers of inflammation and oxidative stress in adults: A systematic review and meta-analysis of randomized controlled trials

The current systematic review and meta-analysis of randomized controlled trials (RTCs) was conducted to summarize the effect of ginger supplementation on biomarkers of inflammation and oxidative stress in adults. Electronic databases including PubMed, Scopus, Web of Science, Cochrane Library and Google Scholar were systematically searched up to February 2018 to identify eligible RCTs which assessed the effect of ginger on C-reactive protein (CRP), interleukin-6 (IL-6) tumor necrosis factor (TNF-α), total antioxidant capacity (TAC) and lipid peroxidation products like malondialdehyde (MDA). Fourteen studies were eligible to be included in the quantitative analysis. Results from meta-analysis suggested that CRP (−0.8 mg/L, 95 % CI: −1.17 to −0.43; I2 = 53 %), IL-6 (−2.26 pg/mL; 95 % CI: −4.00 to −0.52; I2 = 58 %) and TNF-α (−1.33 pg/mL; 95 % CI: −1.85 to −0.80; I2 = 55%) were significantly reduced by ginger supplementation. The pooled effect size indicated a significant increase in blood TAC levels after ginger consumption (1.26 μmol/L; 95 % CI: 0.17–2.35; I2 = 84%). Ginger had no significant effect on MDA (−0.29 μmol/L; 95 % CI: −1.06 to 0.47; I2 =78%). Subgroup analysis showed that the effect of ginger on CRP and TNF-α is more pronounced in studies with >80-days’ intervention. When studies were categorized based on hs-CRP/CRP, the effect of ginger was significant in both subgroups. In conclusion, the present study suggested that supplementation with ginger can improve health status in adults by lowering inflammatory and oxidative stress markers. Future trials with high methodological quality are needed to support the beneficial potential (anti-inflammatory and antioxidant effects) of ginger