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 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 LDL-C/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.