Written by Alexa Heathorn, MS, CNS-c, Science Writer. Daily supplementation of high-phenolic extra virgin olive oil (8 g/day, 1021 mg/kg phenols) for 4 weeks improved lipid profiles in patients with hyperlipidemia, leading to reductions in total cholesterol and lipoprotein(a) and increases in HDL cholesterol compared with lower-phenolic olive oil at higher doses.

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide¹. It encompasses conditions such as elevated cholesterol, which contributes to 2.6 million deaths annually, hyperlipidemia, atherosclerosis, ischemic heart disease, and stroke¹. Lipid profiles are important markers of cardiovascular health and include measurements of total blood cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides, lipoprotein(a) [Lp(a)], and apolipoproteins A1 (ApoA1) and B (ApoB). Abnormal values of these markers are strongly associated with the development of cardiovascular disease, including atherosclerosis—the major cause of CVD—and hyperlipidemia, the most prevalent modifiable risk factor¹. The global burden of CVD makes it a critical target for both pharmacological and lifestyle-based interventions, including dietary components such as extra virgin olive oil (EVOO), which may favorably impact lipid profiles¹.

Extra virgin olive oil (EVOO), a staple of the Mediterranean diet, has been extensively studied for its health-promoting properties¹. It is rich in polyphenols such as hydroxytyrosol, tyrosol, oleocanthal, and oleacein, compounds known for their antioxidant, anti-inflammatory, and cardioprotective effects. These bioactive molecules help protect blood lipids from oxidative stress, improve endothelial function, and reduce risk factors for atherosclerosis¹. Clinical trials have demonstrated that olive oil polyphenols can improve HDL (the “good” cholesterol) and reduce LDL oxidation (the “bad” cholesterol) in a dose-dependent manner, meaning that greater EVOO intake yields stronger lipid benefits¹. According to European Union Regulation 432/2012, olive oils containing more than 5 mg of hydroxytyrosol and its derivatives per 20 g are permitted to carry a health claim for protecting blood lipids from oxidative damage¹. However, most prior studies have tested fixed oil volumes in healthy individuals, leaving open the question of whether smaller amounts of high-phenolic EVOO could provide equal or superior benefits compared with larger amounts of lower-phenolic EVOO in patients with hyperlipidemia¹.

To address this gap, a single-blind, randomized clinical trial was conducted to assess the effects of two types of EVOO with differing polyphenol content and dosages on the lipid profiles of patients with hyperlipidemia¹. Fifty patients were randomized to receive either a higher-dose, lower-phenolic EVOO (414 mg/kg phenols; 20 g/day) or a lower-dose, higher-phenolic EVOO (1021 mg/kg phenols; 8 g/day) for 4 weeks¹. To provide comparison, 20 healthy individuals were also assigned to one of the two EVOO groups for the same duration¹. Outcomes measured included total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides, lipoprotein(a) [Lp(a)], and apolipoproteins A1 (ApoA1) and B (ApoB)¹.

The results were as follows after 4 weeks of supplementation:

• Total Cholesterol: Patients consuming the higher-phenolic, lower-dose EVOO showed a greater reduction compared with the lower-phenolic, higher-dose group (p = 0.045).
• HDL (High-Density Lipoprotein): Significant increase observed in hyperlipidemic patients compared to healthy individuals (p < 0.001).
• Lp(a) (Lipoprotein a): Significant reduction in hyperlipidemic patients compared to controls (p = 0.040).
• LDL, ApoA1, ApoB, and Triglycerides: No statistically significant differences between EVOO groups, though trends favored the high-phenolic oil.
  Gender Effects: No significant differences were observed between men and women.

Potential limitations of the study include:

• The intervention period was relatively short (4 weeks), which limits understanding of the long-term effects of EVOO on lipid profiles and cardiovascular outcomes.
• The sample size was modest (70 participants total), which reduces the statistical power of the findings and limits their generalizability to broader populations.
• The trial used a single-blind design where investigators were aware of group allocation, which could introduce bias in monitoring or data interpretation.
• The study did not include a placebo control group (e.g., refined olive oil with minimal phenolic content), so it is difficult to separate the effects of polyphenols from the benefits of olive oil itself.
• All participants were recruited from a single center in Greece, and the EVOOs were derived exclusively from the Koroneiki olive variety, which may limit generalizability to other populations or olive cultivars.
• Dietary intake, physical activity, and other lifestyle factors outside of the intervention were not formally monitored, meaning unmeasured variables could have influenced outcomes.
• The study measured only lipid outcomes and did not include biomarkers of inflammation, oxidative stress, or endothelial function, which could have provided insight into underlying mechanisms.

This randomized clinical trial demonstrated that daily consumption of extra virgin olive oil (EVOO) improved lipid profiles in patients with hyperlipidemia, with the greatest benefits seen when using a lower dose of high-phenolic EVOO compared to a higher dose of lower-phenolic oil¹. Specifically, high-phenolic EVOO led to greater reductions in total cholesterol and favorable changes in HDL and Lp(a), suggesting that polyphenol concentration may be more important than the total amount of oil consumed¹. These findings highlight the potential role of high-phenolic EVOO as part of dietary strategies for managing hyperlipidemia and reducing cardiovascular risk. From a practical standpoint, consumers may benefit from choosing EVOO verified to contain higher polyphenol content, while producers may find value in developing and labeling high-phenolic formulations¹. However, longer-term studies with larger, more diverse populations and mechanistic biomarkers are needed to confirm these results and clarify their broader applicability.

Source: Kourek, Christos, Emmanouil Makaris, Prokopios Magiatis, Virginia Zouganeli, Vassiliki Benetou, Alexandros Briasoulis, Andrew Xanthopoulos et al. “Effects of High-Phenolic Extra Virgin Olive Oil (EVOO) on the Lipid Profile of Patients with Hyperlipidemia: A Randomized Clinical Trial.” Nutrients 17, no. 15 (2025): 2543.

© 2025 by the authors. 

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Posted October 14, 2025.

Alexa Heathorn, MS, CNS-c, is a clinical nutritionist specializing in metabolic health, hormonal balance, and gastrointestinal restoration through root-cause functional nutrition. She earned her master’s degree in Nutrition from Bastyr University and is currently a Certified Nutrition Specialist (CNS) candidate. Alexa also works as a research writer and functional health consultant, translating complex science into actionable strategies for practitioners and wellness companies. Learn more at www.bloomedwellness.com.

References:

1. Kourek C, Makaris E, Magiatis P, et al. Effects of High-Phenolic Extra Virgin Olive Oil (EVOO) on the Lipid Profile of Patients with Hyperlipidemia: A Randomized Clinical Trial. Nutrients. Aug 2 2025;17(15)doi:10.3390/nu17152543