PerspectivesAre you interested in submitting a Perspective Article? Be sure to read The Science Advisory Board's Editorial Guides for Perspective Articles. Click here. The Beneficial Effects of Olive Oil by Tahira Farooqui, Ph.D. Olive oil is the main component of Mediterranean diet, which is principally a vegetarian diet. Other components of Mediterranean diet are plant-based foods, and wine. Olive oil is obtained from the fruit olive (Olea europaea L.). Its plant belongs to the Oleaceae family. Olive oil has been used in the past as a fuel for traditional oil lamps, but now it is commonly used in cooking, pharmaceuticals, cosmetics and soaps. The composition of olive oil varies by cultivar, region, altitude, time of harvest, and extraction process. It is composed mainly of oleic acid (monounsaturated fatty acid), palmitic acid (saturated fatty acid), and other fatty acids along with traces of squalene, and sterols including phytosterol and tocosterols. Extra-virgin olive oil (unprocessed olive oil) contains micronutrients with potent antioxidant properties. These micronutrients include polyphenolic antioxidants, Tyrosol [2-(4-hydroxyphenyl)ethanol], hydroxytyrosol, oleuropein, and oleocanthal. Interest in the health benefits of Mediterranean diet has increased tremendously, because of its link with greater longevity and lower cardiovascular disease rate, cancer, type II diabetes, and neurodegenerative diseases [1-2]. Despite the high complexity of Mediterranean diet nutrients composition, olive oil has emerged as its principal beneficial component. Olive oil not only provides higher percentage of energy, but a lot of bioactive nutrients that promote human health. It is becoming increasingly evident that supplementation of olive oil in diet improves the major risk factors for cardiovascular disease, such as the lipoprotein profile, blood pressure, glucose metabolism and antithrombotic profile [2]. Multiple mechanisms have been proposed to explain the beneficial effects of the Mediterranean diet. Excessive oxidative stress and inflammation are closely associated with the pathogenesis of many human diseases (such as cancer, obesity, type II diabetes, cardiovascular diseases, neurodegenerative diseases and aging). Phenolic compounds present in olive oil have anti-inflammatory activity; therefore, they can modulate signal transduction pathways to elicit their beneficial effects in human diseases (Table 1). These mechanisms include modulation of pro-inflammatory gene expression such as cyclooxygenase, lipoxygenase, nitric oxide synthases and several pivotal cytokines, mainly by acting through nuclear factor-kappa B and mitogen-activated protein kinase signaling [3]. Extra virgin olive oil extract retards the translocation of p50 and p65 NF-kappa B in both un-stimulated and phorbol-myristate acetate (PMA)-challenged monocytes and monocyte-derived macrophages in a dose-dependent manner [4]. Inhibition is more effective for the p50 subunit than p65 [5]. This effect occurs at concentrations found in human plasma after nutritional ingestion of virgin olive oil and is quantitatively similar to the effect exerted by ciglitazone, a peroxisome proliferator-activated receptor (PPAR) gamma ligand. However, extra-virgin olive oil extract has no effect on PPAR-gamma expression in monocytes, suggesting that beneficial effects of extra-virgin olive oil are due to its ability to inhibit NF-kappa B activation in human monocyte/macrophages [5]. Furthermore, polyphenolic compounds found in olive oil, including oleuropein, inhibit the adhesion of monocyte cells to the blood vessel lining, a process that is involved in the development of atherosclerosis. Another component of olive oil, (-)-oleocanthal (1), inhibits COX-1 and COX-2, which convert arachidonic acid to eicosanoids. This property is similar to ibuprofen [6-7]. In addition, diet enriched in virgin olive oil reduces the sensitivity of platelets to aggregation by decreasing von Willebrand and thromboxane B2 plasma levels [8]. Virgin olive oil retards inflammation by inhibiting platelet activating factor, a lipid mediator that plays an important role not only in the clotting process by mediating platelet aggregation but also activating immune cells and their binding to the endothelial wall [9]. These studies indicate that olive oil components interferes with the inflammatory response within atherosclerotic lesions by inhibiting endothelial activation involved in monocyte recruitment during early atherogenesis and macrophage production of inflammatory cytokines and matrix degrading enzymes, thus, improving vascular stability. The intake of the polyphenol-enriched breakfast prepared from olive oil increases plasma concentrations of nitrates/nitrites and decreases levels of lipoperoxides, and 8-epi prostaglandin-F2 than breakfast prepared from low polyphenol fat meal. Both these parameters are positively correlated to enhanced endothelial function. In addition, olive oil components also inhibit platelet aggregation. Many studies in humans have shown that the intake of fat in olive oil may have protective effects against age-related cognitive decline and Alzheimer disease. The micronutrients found in virgin olive oil modulate homeostasis and antithrombotic properties in cardiovascular and cerebrovascular systems. Oleic acid inhibits gap junction permeability and increases glucose uptake in cultured rat astrocytes. The molecular mechanism of oleic acid-mediated inhibition of gap junctions remains unknown. However, it is proposed that oleic may acts by stimulating protein kinase C [10]. Oleic acid has been reported to suppress lung tumorigenesis in mice, which is probably due to the inhibition of PGE2 production and inactivation of the Erk cascade [11].  Collective evidence suggests that olive oil is a unique component of Mediterranean diet. The importance of olive oil is mainly attributed to: (1) its high content of oleic acid, (2) balanced amount of polyunsaturated fatty acids, and (3) phenolic compounds that act as antioxidants. The medicinal potential of olive oil has been largely attributed to antioxidant effects of phenolic compounds, which may retard chronic human diseases due to their antioxidant and anti-inflammatory actions. Recent studies have indicated that olive oil has micronutrients that produce effects similar to ibuprofen. Based on the evidence, it can be suggested that one has to go beyond antioxidant effects of phenolic compounds to elucidate olive oil’s benefits to human health. Furthermore, lipid mediators of oleic acid are still uncertain. Thus, further studies are required to understand oleic acid-mediated signaling mechanism(s) leading to its beneficial effects on humans. References: 1. Pérez-Jiménez F, Alvarez de Cienfuegos G, Badimon L, Barja G, Battino M, Blanco A, and others. 2005. International conference on the healthy effect of virgin olive oil. Eur J Clin Invest. 35: 421-424. 2. Lopez-Miranda J, Delgado-Lista J, Perez-Martinez P, Jimenez-Gómez Y, Fuentes F, Ruano J, and others. 2007. Olive oil and the haemostatic system. Mol Nutr Food Res. 51:1249-1259. 3. Santangelo C, Vari R, Scazzocchio B, Di Benedetto R, Filesi C, Masella R. 2007. Polyphenols, intracellular signalling and inflammation. Ann 1st Super Sanita. 44:394-405. 4. Pérez-Jiménez F, Ruano J, Perez-Martinez P, Lopez-Segura F, Lopez-Miranda J. 2007. The influence of olive oil on human health: not a question of fat alone. Mol Nutr Food Res. 51:1199-1208. 5. Brunelleschi S, Bardelli C, Amoruso A, Gunella G, Ieri F, Romani A, and others. 2007. Minor polar compounds extra-virgin olive oil extract (MPC-OOE) inhibits NF-kappa B translocation in human monocyte/macrophages. Pharmacol Res. 56:542-549. 6. Beauchamp GK, Keast RS, Morel D, Lin J, Pika J, Han Q, and others. 2005. Phytochemistry: ibuprofen-like activity in extra-virgin olive oil. Nature. 437:45-46. 7. Smith AB 3rd, Sperry JB, Han Q. 2007. Syntheses of (-)-oleocanthal, a natural NSAID found in extra virgin olive oil, the (-)-deacetoxy-oleuropein aglycone, and related analogues. J Org Chem. 72:6891-6900. 8. Ruano J, Lopéz-Miranda J, de la Torre R, Delgado-Lista J, Fernádez J, Caballero J, and others. 2007. Intake of phenol-rich virgin olive oil improves the postprandial prothrombotic profile in hypercholesterolemic patients. Am J Clin Nutr. 86:341-346. 9. Ruano J, Lopez-Miranda J, Delgado-Lista J, Fernandez J, Caballero J, Covas MI, and others. 2007. Intake of phenol-rich virgin olive oil improves the postprandial prothrombotic profile in hypercholesterolemic patients. Am J Clin Nutr. 86:341-346. 10. Khan WA, Blobe GC, Hunnun YA. 1992. Activation of protein kinase C by oleic acid. Determination and analysis of inhibition by detergent micelles and physiologic membranes: requirement for free oleate. J Biol Chem. 267:3605-3612. 11. Yamaki T, Yano T, Satoh H, Endo T, Matsuyama C, Kumagari H, and others. (2002). High oleic acid oil suppresses lung tumorigenesis in mice through the modulation of extracellular signal-regulated kinase cascade. Lipids. 37:783-788. 12. Sant M, Allemani C, Sieri S, Krogh V, Menard S, Tagliabue E, and others. 2007. Salad vegetables dietary pattern protects against HER-2-positive breast cancer: a prospective Italian study. Int J Cancer. 121:911-914. ### << Previous Next >> [ View All Perspectives ] |
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