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The Effect of Polyphenols in Olive Oil on Heart Disease Risk Factors
A Randomized Trial
- María-Isabel Covas, MSc, PhD;
- Kristiina Nyyssönen, MSc, PhD;
- Henrik E. Poulsen, MD, PhD;
- Jari Kaikkonen, MSc, PhD;
- Hans-Joachim F. Zunft, MD, PhD;
- Holger Kiesewetter, MD, PhD;
- Antonio Gaddi, MD, PhD;
- Rafael de la Torre, MSc, PhD;
- Jaakko Mursu, MSc;
- Hans Bäumler, MSc, PhD;
- Simona Nascetti, MD, PhD;
- Jukka T. Salonen, MD, PhD;
- Montserrat Fitó, MD, PhD;
- Jyrki Virtanen, MSc;
- Jaume Marrugat, MD, PhD; and
- for the EUROLIVE Study Group
- From the Municipal Institute for Medical Research, Barcelona, Spain; University of Kuopio and Oy Jurilab, Kuopio, Finland; Rigshospitalet, University Hospital, Copenhagen, Denmark; German Institute of Human Nutrition, Postdam-Rehbruecke, Germany; Charité-University of Medicine of Berlin, Berlin, Germany; and Centro per lo Studio dell'Arteriosclerosi e delle Malattie Dismetaboliche “GC Descovich,” Policlinico S. Orsola-Malpighi, Bologna, Italy.
Abstract
Background: Virgin olive oils are richer in phenolic content than refined olive oil. Small, randomized, crossover, controlled trials on the antioxidant effect of phenolic compounds from real-life daily doses of olive oil in humans have yielded conflicting results. Little information is available on the effect of the phenolic compounds of olive oil on plasma lipid levels. No international study with a large sample size has been done.
Objective: To evaluate whether the phenolic content of olive oil further benefits plasma lipid levels and lipid oxidative damage compared with monounsaturated acid content.
Design: Randomized, crossover, controlled trial.
Setting: 6 research centers from 5 European countries.
Participants: 200 healthy male volunteers.
Measurements: Glucose levels, plasma lipid levels, oxidative damage to lipid levels, and endogenous and exogenous antioxidants at baseline and before and after each intervention.
Intervention: In a crossover study, participants were randomly assigned to 3 sequences of daily administration of 25 mL of 3 olive oils. Olive oils had low (2.7 mg/kg of olive oil), medium (164 mg/kg), or high (366 mg/kg) phenolic content but were otherwise similar. Intervention periods were 3 weeks preceded by 2-week washout periods.
Results: A linear increase in high-density lipoprotein (HDL) cholesterol levels was observed for low-, medium-, and high-polyphenol olive oil: mean change, 0.025 mmol/L (95% CI, 0.003 to 0.05 mmol/L), 0.032 mmol/L (CI, 0.005 to 0.05 mmol/L), and 0.045 mmol/L (CI, 0.02 to 0.06 mmol/L), respectively. Total cholesterol–HDL cholesterol ratio decreased linearly with the phenolic content of the olive oil. Triglyceride levels decreased by an average of 0.05 mmol/L for all olive oils. Oxidative stress markers decreased linearly with increasing phenolic content. Mean changes for oxidized low-density lipoprotein levels were 1.21 U/L (CI, −0.8 to 3.6 U/L), −1.48 U/L (−3.6 to 0.6 U/L), and −3.21 U/L (−5.1 to −0.8 U/L) for the low-, medium-, and high-polyphenol olive oil, respectively.
Limitations: The olive oil may have interacted with other dietary components, participants' dietary intake was self-reported, and the intervention periods were short.
Conclusions: Olive oil is more than a monounsaturated fat. Its phenolic content can also provide benefits for plasma lipid levels and oxidative damage.
International Standard Randomised Controlled Trial number: ISRCTN09220811.
Article and Author Information
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Acknowledgments: The authors thank the EUROLIVE Investigators: R. Elosua, J.S. Vila, H. Schroder, and M. Farré-Albaladejo, Municipal Institute for Medical Research (IMIM), Barcelona, Spain, for methodologic and statistical assistance, performing diet record analyses, and management assistance; S. Voutilainen, T. Rissanen, T.P. Tuomainen, and V.P. Valkonen, Research Institute of Public Health, Kuopio University, Kuopio, Finland, for management and technical assistance; S. D'Addato, E. Grandi, S. Linarello, Z. Sangiorgio, and A. Fiorito, Policlinico S. Orsola-Malpighi, Bologna, Italy, for technical assistance and performing diet record analyses; T. Vilppo, Oy Jurilab, Kuopio, Finland, for performing oxidative and antioxidative biomarkers; and M.C. López-Sabater, K. De la Torre, and R.M. Lamuela-Raventós, Barcelona University, Barcelona, Spain, for the olive oil analyses.
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Grant Support: By grant QLK1-CT-2001-00287 from the Commission of the European Communities Quality of Life and Management of Living Resources program.
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Potential Financial Conflicts of Interest: None disclosed.
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Requests for Single Reprints: María-Isabel Covas, PhD, Lipids and Cardiovascular Epidemiology Unit, Municipal Institute for Medical Research (IMIM), Carrer Dr. Aiguader, 80, 08003 Barcelona, Spain; e-mail, mcovas{at}imim.es.
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Current Author Addresses: Drs. Covas, Fitó, and Marrugat: Lipids and Cardiovascular Epidemiology Unit, Municipal Institute for Medical Research (IMIM), Carrer Dr. Aiguader, 80, 08003 Barcelona, Spain.
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Dr. Nyyssönen, Mr. Mursu, and Mr. Virtanen: Research Institute of Public Health, University of Kuopio, Harjulantie 1B, 70211 Kuopio, Finland.
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Dr. Poulsen: Department of Clinical Pharmacology, Rigshospitalet, University Hospital Copenhagen, 20 Tagensvej, 2200 Copenhagen, Denmark.
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Drs. Kaikkonen and Salonen: Oy Jurilab, Neulaniementie 2L 12, 70210 Kuopio, Finland.
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Dr. Zunft: German Institute of Human Nutrition (DIFE), Arthur-Scheunert-Allee, 114-116, 14558 Postdam-Rehbruecke, Germany.
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Drs. Kiesewetter and Bäumler: Charité-University of Medicine of Berlin, Schumannstr, 20/21, 10117 Berlin, Germany.
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Drs. Gaddi and Nascetti: Dipartimento di Medicina Clinica e Biotecnologia Applicata, Policlinico S. Orsola-Malpighi, Via Massarenti, 9, 40138 Bologna, Italy.
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Dr. de la Torre: Pharmacology Research Unit, Municipal Institute for Medical Research (IMIM), Carrer Dr. Aiguader, 80, 08003 Barcelona, Spain.
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Author Contributions: Conception and design: M.-I. Covas, K. Nyyssönen, H.E. Poulsen, H.-J.F. Zunft, H. Kiesewetter, A. Gaddi, J.T. Salonen, J. Marrugat.
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Analysis and interpretation of the data: M.-I. Covas, J. Kaikkonen, H. Kiesewetter, R. de la Torre, J. Mursu, J. Marrugat.
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Drafting of the article: M.-I. Covas, R. de la Torre, J. Marrugat.
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Critical revision of the article for important intellectual content: K. Nyyssönen, H.E. Poulsen, J. Kaikkonen, H.-J.F. Zunft, H. Kiesewetter, A. Gaddi, J. Mursu, H. Bäumler, S. Nascetti, J.T. Salonen, M. Fitó, J. Virtanen, J. Marrugat.
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Final approval of the article: M.-I. Covas, K. Nyyssönen, H.E. Poulsen, J. Kaikkonen, H.-J.F. Zunft, A. Gaddi, R. de la Torre, H. Bäumler, S. Nascetti, J.T. Salonen, M. Fitó, J. Marrugat.
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Provision of study materials or patients: K. Nyyssönen, H.E. Poulsen, A. Gaddi, S. Nascetti, M. Fitó, J. Marrugat.
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Obtaining of funding: M.-I. Covas, K. Nyyssönen, J. Kaikkonen, H.-J.F. Zunft, H. Kiesewetter, J.T. Salonen, J. Marrugat.
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Administrative, technical, or logistic support: J. Mursu, H. Bäumler, J. Virtanen.
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Collection and assembly of data: K. Nyyssönen, J. Kaikkonen, H.-J.F. Zunft, H. Bäumler, S. Nascetti, M. Fitó, J. Virtanen.
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