Effects of flaxseed supplementation on inflammatory biomarkers: A GRADE-assessed systematic review and meta-analysis of randomized controlled trials

Several studies reported the benefits of flaxseed on inflammatory biomarkers, while others reported conflicting findings. Thus, the aim of this meta-analysis was to assess the impacts of flaxseed on inflammatory biomarkers in adults. Databases including Embase, PubMed, Scopus, and Web of Sciences were searched till February 2024. The 54 RCTs were included in the final analysis, which involved 3000 individuals from 12 countries. Overall, the flaxseed supplementation had a significant reduction in C-reactive protein (CRP) (SMD = −0.46; 95 % CI: −0.70, −0.23, P < 0.001; I² = 82.9 %, P < 0.001), and interleukin 6 (IL-6) (SMD = −0.64, 95 % CI: −1.13, −0.16, P = 0.010; I² = 92.7, P < 0.001). Furthermore, flaxseed did not significantly change the concentration of tumor necrosis factor α (TNF-α) (SMD = −0.17; 95 % CI: −0.63, 0.29, P = 0.467; I² = 92, P < 0.001). Flaxseed supplementation significantly decreased serum concentrations of CRP and IL-6, but not TNF-a. Thus, this meta-analysis suggests that the current evidence supports the potential benefits of flaxseed in managing inflammatory conditions.