Application of flaxseed as an effective approach for improving lipid profile parameters: An updated systematic review and meta-analysis of randomized controlled trials

Background: Numerous studies have shown the beneficial effects of flaxseed on lipid profile parameters; however, some others have reported contradictory results.Aim of the review: The current study, therefore, aimed to provide a thorough understanding of the effects of flaxseed on lipid profile parameters in adults. Methods: To this end, a comprehensive systematic search was conducted to collect the required trials from PubMed, Scopus, Embase, Cochrane Library, Web of Science databases, and Google Scholar up to December 2022.Results: 75 trials were included in our meta-analysis (two trials were only presented as a systematic review). Our study results indicated that the flaxseed supplementation significantly decreased the total levels of cholesterol (TC) (SMD: -0.57; 95% CI: -0.80, -0.33, P < 0.001), triglyceride (TG) (SMD: -0.61; 95% CI: -0.87, -0.35, P < 0.001), low-density lipoprotein-cholesterol (LDL-C) (SMD: -0.36; 95% CI: -0.61, -0.11; P = 0.005), and LDLC/HDL-C ratios (SMD: -0.92, 95% CI: -1.35, -0.49, P < 0.010). However, flaxseed did not change the levels of high-density lipoprotein-cholesterol (HDL-C) (SMD: 0.16; 95% CI: -0.03, 0.35, P = 0.097), and TC/HDL-C ratio (SMD: -0.35; 95% CI: -0.81, 0.11; P = 0.139).Conclusion: It was concluded that the flaxseed supplementation may have improved the lipid profile. Therefore, it was recommended that flaxseed should be used as an adjuvant anti-hyperlipidemic agent.