Beneficial effects of dietary supplementation with olive oil, oleic acid, or hydroxytyrosol in metabolic syndrome: Systematic review and meta-analysis

Abstract

[eng] Background and aims: Olive oil and components might have a beneficial effect on Metabolic Syndrome (MetS).</p><p>The aim of this review and meta-analysis was to assess whether those effects are related to hydroxytyrosol or</p><p>oleic acid contents, or the combination of them as olive oil, and how powerful is this effect.</p><p>Methods: A systematic literature search was performed in MEDLINE via Pubmed, Web of Science (WOS) core</p><p>collection, and Virtual Health Library (VHL) via LILACS and IBECS (Spain). MeSH terms used were “obesity”,</p><p>“body weight”, “body mass index”, “adipose tissue”, “lipid metabolism”, “LDL”, “HDL”, “VLDL”, “insulin resistance”,</p><p>“glucose”, “insulin”, “hypertension”, “arterial pressure”, “olive oil”, “oleic acid”, and other (non-MeSH)</p><p>terms: “total antioxidant capacity”, “total antioxidant status”, “hydroxytyrosol” (PROSPERO ID:</p><p>CRD42021247614). Results of the included studies were meta-analyzed with the RevMan 5.3 program, assuming</p><p>a random effects model.</p><p>Results: 76 articles (67 different trials) were identified. Hydroxytyrosol had no effect on MetS [combined standardized</p><p>mean differences (SMD) = 0.01 (CI 95%: [-0.23, 0.25], I2 = 83%; p = 0.920)]. Oleic acid had no</p><p>significant beneficial effect on MetS [SMD = 0.03 (CI 95%: [-0.01, 0.07], I2 = 0%); p = 0.150], but it improved</p><p>lipid profile [SMD = 0.06 (CI 95%: [-0.00, 0.12], I2 = 0%); p = 0. 050]. Olive oil had no effect on MetS [SMD =</p><p> 0.01 (CI 95%: [-0.05, 0.03]), I2 = 55%; p = 0.550)]. The supplementation with hydroxytyrosol, oleic acid or</p><p>olive oil showed a beneficial effect on antioxidant capacity related to components of MetS [SMD = 0.31 (CI 95%:</p><p>[-0.34, 0.95], I2 = 81%)]; p = 0.35).</p><p>Conclusion: Most articles compared olive oil and oleic acid with other strategies specially designed for MetS</p><p>management. Our findings suggest that olive oil or oleic acid consumption are as good as the other strategies to</p><p>manage MetS.</p>