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

Numerous studies have shown the beneficial effects of flaxseed on lipid profile parameters; however, some others have reported contradictory results. The current study, therefore, aimed to provide a thorough understanding of the effects of flaxseed on lipid profile parameters in adults. 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. 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). 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.