‘Not How Much, But Which’: High-Phenolic Olive Oil Improves Lipid Profile in Patients with Hyperlipidemia

A small randomized clinical trial found that in people with high cholesterol, high-polyphenol extra virgin olive oil (EVOO) improved lipid levels better than lower-polyphenol oil, even when consumed in smaller amounts. Over four weeks, patients’ “good” HDL cholesterol increased, the atherogenic marker Lp(a) decreased, and total cholesterol dropped more in the high-phenol EVOO group. The study was published in the journal Nutrients.

Background

• Why not just “any olive oil,” but specifically phenolic olive oil? EVOO’s cardioprotective reputation is not only due to oleic acid, but also to phenolic compounds (hydroxytyrosol, tyrosol, oleocanthal, oleacein, and oleuropein/ligstroside aglycones). They protect LDL from oxidation and improve the properties of HDL. The European regulator has approved the health claim: “olive phenols protect LDL particles from oxidative damage,” if the oil contains ≥5 mg of hydroxytyrosol and its derivatives per 20 g of oil.
• Randomized data support a high phenolic profile. In the multicenter EUROLIVE (healthy volunteers, crossover), the more phenolic oil was better at increasing HDL and more at reducing LDL oxidizability — the effect depended on the phenol content. Later, EVOO polyphenols were shown to improve HDL function (including the ability to remove cholesterol from cells) and reduce the atherogenicity of LDL in humans.
• The context of the “big outcomes”: not just markers. In PREDIMED (primary prevention), a Mediterranean diet enriched with EVOO reduced the risk of major cardiovascular events compared with a control diet; the results were confirmed in a re-publication with adjustments for randomization. This sets the “background”: good-quality EVOO is one of the pillars of a working strategy.
• Why the Lp(a) finding is remarkable. Lipoprotein(a) is a genetically determined, “stubborn” risk factor for atherothrombosis and aortic valve stenosis; it is almost unaffected by standard diets and statins. Of the approved drugs, only PCSK9 inhibitors provide a moderate decrease in Lp(a), and “strong” effects (up to 80–90%) are currently demonstrated only by experimental anti-Lp(a) oligonucleotides (e.g., pelacarsen) — we are still waiting for the outcomes in phase 3. Therefore, even a small shift in Lp(a) against the background of dietary intervention looks unusual and deserves to be tested in longer RCTs.
• How to calculate “high phenolic content” and why it is difficult. Science and industry agree that “high-phenolic” is usually >500 mg/kg of total phenols (such oil will maintain the regulatory threshold of ≥250 mg/kg for at least a year). But the phenol content varies greatly: the variety (often “rich” ones — Greek Koroneiki, etc.), the ripeness of the fruit, the technology, and then — storage (light/temperature) can “eat up” up to ≈40–50% of phenols in 12 months. Hence the importance of analyzing the batch and storage conditions, and not just the words “extra virgin” on the label.
• How exactly are "those" phenols measured? To meet the health claim, hydroxytyrosol and its derivatives are considered; validated methods (HPLC, NMR, spectrophotometric tests) are used in practice, and EFSA/scientific reviews emphasize the need for correct analytics: different methods give different numbers, which is important when comparing oils.
• Why the logic of the new RCT “less oil – more phenols” makes sense. If phenols are the key active ingredient, then comparing oils “by spoonfuls” is incorrect. EVOO, which is more concentrated in phenols, can provide the same (or more) “phenolic” equivalent with fewer calories/fat – this is a practical plus for people with dyslipidemia who also monitor their energy balance. Previously observed improvements in HDL function and protection of LDL from oxidation “underpin” the biology of such a strategy.
• What we don't know yet. Short RCTs of 3-6 weeks are good at catching markers (HDL function, LDL oxidation, hsCRP, etc.), but for "hard" outcomes (heart attacks/strokes), long and large studies are needed; it is also important to standardize methods for measuring phenols and selecting a dose based on phenol equivalent, not grams of oil.

What exactly was compared?

A Greek team randomized 50 patients with hyperlipidemia to two EVOO options:

• Low phenolic, high dose: 414 mg/kg polyphenols, 20 g/day;
• High phenolic, lower dose: 1021 mg/kg polyphenols, 8 g/day.

Design trick: in both groups, the daily polyphenol intake was equalized (~8.3 mg/day) by measuring the composition of the oils using NMR spectroscopy. Additionally, 20 healthy people were included for comparison, who were given the same oil options. The intervention lasted 4 weeks; the primary endpoints were total cholesterol, LDL, HDL, triglycerides, Lp(a), ApoA1 and ApoB.

Main results

• Total cholesterol decreased more significantly in the high-phenolic EVOO group at the lower dose: the time × group interaction yielded β = −17.06 mg/dL (95% CI −33.29…−0.83; p = 0.045). In other words, the concentration of polyphenols was more important than the volume of oil.
• In hyperlipidemic patients, EVOO increased HDL (patients vs. healthy controls × time interaction: p < 0.001) and decreased Lp(a) (p = 0.040) compared to healthy controls, in whom these changes were more modest. This is interesting: Lp(a) is considered a “stubborn” risk factor, little influences it.
• LDL, ApoA1 and ApoB did not change significantly between oil variants over 4 weeks; triglycerides also showed no obvious differences.

Why does this make biological sense?

EVOO polyphenols (hydroxytyrosol, tyrosol and their derivatives - oleocanthal, oleacein, oleuropein/ligstroside aglycones) have antioxidant and anti-inflammatory effects and protect lipoproteins from oxidation. European regulation EU 432/2012 allows "health claims" for oils with ≥5 mg of corresponding phenols per 20 g - both oils in the study exceeded this threshold, but the high-phenolic oil gave a better clinical response with less fat and calories.

How They Did It (and Who You Can Trust)

• Design: Single-blind RCT, Kalamata, Greece, October 2021–March 2022; Koroneiki olive variety in both oils; dietary control—“maintain usual diet/medications”.
• Who reached the finish line: 22 patients in the “low-phenolic/20 g” group and 28 in the “high-phenolic/8 g” group; of the healthy ones, 9 and 11 people, respectively.

What does this mean "for the kitchen" right now?

• If you’re choosing EVOO for your heart, look for polyphenols, not just the “extra virgin” label. A high phenolic profile can provide health benefits even with a smaller volume of oil (less fat and calories). Look for hydroxytyrosol/tyrosol analysis or lab certification; store in a dark bottle, keep cool.
• For LDL, 4 weeks is not enough - this indicator is often "lazy". But HDL and especially Lp(a) "shifted" in this work, which adds arguments in favor of high-phenolic oils.

Where is the thinness in the evidence?

• There was no placebo/refined control, just "oil vs. oil" with different phenolics; the researchers knew who was in which group (single-blind).
• Short duration (4 weeks), small sample size, and diet not closely monitored - cannot accurately separate the contribution of polyphenols from background. Longer, double-blind RCTs are needed.

Conclusion

In people with hyperlipidemia, EVOO generally improves the lipid profile, and high-phenolic oil at a lower dose was more effective for total cholesterol and was accompanied by an increase in HDL and a decrease in Lp(a). In practice, this means: when choosing olive oil, the quality composition (polyphenols) is important, and not just “more oil in a spoon.”

Source: Kourek C. 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(15):2543, 2025. https://doi.org/10.3390/nu17152543