Document Type : Review Article
Authors
1
Department of Nutrition, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
2
Department of Nutrition, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
3
The Department of Clinical Nutrition, School of Nutrition and Food Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
4
Department of Clinical Nutrition, School of Nutrition and Food Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
5
Department of Midwifery, Faculty of Nursing and Midwifery, Mashhad Medical Sciences, Islamic Azad University, Mashhad, Iran
6
Nutrition
Abstract
Objective: This study evaluated the effects of flaxseed oil (FO, derived from Linum usitatissimum) supplementation on lipid profile parameters in adults.
Materials and Methods: A systematic search was conducted across PubMed, Scopus, Google Scholar, and Web of Science up to February 2025, targeting randomized controlled trials (RCTs) that compared FO supplementation with a control group. A random-effects meta-analysis calculated lipid markers' weighted mean difference (WMD) and 95% confidence interval (CI).
Results: Thirty-six RCTs involving 1,959 participants were analyzed. FO supplementation significantly reduced triglyceride (TG) levels (WMD: -8.04 mg/dl; 95% CI: -15.63 to -0.45; p=0.038) but had no significant effect on total cholesterol (TC) (WMD: -1.15 mg/dl; 95% CI: -5.75 to 3.44; p=0.62), low-density lipoprotein-cholesterol (LDL-C) (WMD: 1.01 mg/dl; 95% CI: -1.35 to 3.41; p=0.41), or high-density lipoprotein cholesterol (HDL-C) (WMD: 0.1 mg/dl; 95% CI: -1.26 to 1.47; p=0.88). Subgroup analyses revealed greater TG and TC reductions in interventions <12 weeks (TG: WMD: -16.86 mg/dl, p=0.005; TC: WMD: -3.5 mg/dL, p=0.03) and significant TG decreases in obese participants (WMD: -18.29 mg/dl, p=0.03). HDL-C increased significantly in individuals with baseline HDL-C ≤40 mg/dl (WMD: 1.35 mg/dl; 95% CI: 0.3 to 2.4; p=0.01). Non-linear dose-response analysis showed significant associations between FO dose and LDL-C (p=0.039) and alpha-linolenic acid intake with LDL-C (p=0.039) and TC (p=0.027).
Conclusion: FO supplementation effectively lowers TG, especially in obese individuals and shorter interventions, and raises HDL-C in those with low baseline levels. While LDL-C and TC show minimal overall change, non-linear dose effects suggest that higher FO and α-Linolenic acid (ALA) doses may influence these markers, necessitating further research on optimal dosing.
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