What does extra virgin olive oil do for blood vessels and the heart - a systematic review of clinical studies

A systematic review of clinical studies on the effects of extra virgin olive oil (EVOO) on cardiovascular health has been published in Nutrients. The authors followed PRISMA/PICO, registered the protocol in PROSPERO, and selected 17 human studies from 2005-2025. Overall conclusion: regular consumption of EVOO, especially polyphenol-rich EVOO, is associated with improvements in key vascular and inflammatory markers and supports both primary and secondary prevention (in people with a history of heart disease). However, this is not a “magic pill,” but a component of the Mediterranean diet, into which EVOO is organically woven.

Background of the study

Cardiovascular disease remains the world’s leading killer, and interest in dietary factors that can reduce risk continues unabated. In this context, extra virgin olive oil (EVOO), a key component of the Mediterranean diet, continually pops up in clinical reviews: EVOO consumers are more likely to have better endothelial function, lower markers of oxidative stress and inflammation, and favorable changes in lipid profiles. A new systematic review in Nutrients collected clinical data from 2005 to 2025 and focused specifically on the effects of EVOO on cardiovascular outcomes and cardiometabolic markers.

The difference of EVOO is not only in monounsaturated fats, but also in the phenolic fraction (hydroxytyrosol, tyrosol and their derivatives, including secoiridoids). It is polyphenols that are responsible for a significant part of the "vascular" benefit: the European Food Safety Authority (EFSA) allows the formulation on the protection of blood lipids from oxidative damage only for oils that contain ≥5 mg of hydroxytyrosol and its derivatives in 20 g. In practice, the content of phenols varies greatly (variety, maturity of olives, milling, storage), so the effect of "oil in general" and high-polyphenol EVOO may differ.

In clinical trials, it was high-polyphenol EVOO that provided the clearest signals: improved flow-mediated dilation (FMD), decreased ox-LDL/hs-CRP, and increased HDL in people with increased CV risk and in the elderly. However, the “hard” endpoints (mortality, heart attack/stroke) in randomized data are still few and varied, so it is more correct to discuss EVOO as a dietary tool as part of a holistic nutritional pattern, rather than as a replacement for standard therapy.

The practical context found in reviews and recommendations is simple: we are usually talking about regular consumption of EVOO as part of a Mediterranean diet, not about “shots” of oil; many studies operate with a range of ~20-30 g/day. High-quality oils - fresh, in dark containers, stored in a cool place - better retain phenols. The scientific task for the coming years is multicenter RCTs with mandatory consideration of the phenolic content of oil and standardized markers of vascular function and inflammation.

What and how was analyzed

We searched PubMed, Cochrane, Web of Science, and Scopus for randomized trials and clinical studies; we included only human studies in English and excluded reviews/meta-analyses and preclinical models. We obtained 17 studies, which were summarized qualitatively (without a pooled meta-assessment due to heterogeneity of protocols). The protocol is registered: PROSPERO 2025 CRD420251029375.

Key findings: what changes in blood and vessels

Under attack by atherosclerosis - endothelium, inflammation, oxidative stress and pressure. Here EVOO gives measurable effects:

• Blood pressure. Intake of 60 ml/day of high-polyphenol EVOO (≈320-360 mg/kg) for 3 weeks reduced systolic pressure by ~2.5-2.7 mmHg (peripheral and central), without significant changes in diastolic pressure or arterial stiffness. For population-level prevention, even such “small” changes are important.
• Endothelial function: In the CORDIOPREV program in patients with diabetes/prediabetes, a Mediterranean diet rich in EVOO improved FMD (flow-dependent vasodilation) compared with a low-fat diet.
• Oxidative stress and inflammation. According to a number of studies, EVOO (and especially its “fortified”/high-polyphenolic variants) reduced ox-LDL, TXB₂, CRP, IL-6, increased total antioxidant capacity of plasma (TAC) and NO metabolites; in hypertensive patients and patients with stable coronary artery disease, this was accompanied by a decrease in SBP.
• Lipids and HDL. In crossover RCTs in healthy adults, HDL increased significantly, while the ability of HDL to carry away cholesterol (efflux) did not change significantly; in one of the trials, a moderate increase in LDL (~0.14 mmol/L) was noted with high-polyphenol oil, which is important to consider.
• Marker associations and long-term risks. In Spanish cohorts, higher total olive oil consumption was associated with lower CVD and stroke risk, with the “optimum” being ~20-30 g/day. In the PREDIMED metabolomic analysis, total EVOO consumption profiles were associated with lower CV event rates (HR per SD ≈ 0.79). There were also signals linking consumption with better ankle-brachial index values (lower risk of peripheral atherosclerosis).

Why does extra virgin "work"?

EVOO is not only monounsaturated oleic fat, but also polyphenols: hydroxytyrosol, tyrosol, oleuropein and derivatives (including secoiridoids: oleocanthal, oleacein). The European Food Safety Authority (EFSA) allows the health declaration: "olive oil polyphenols help protect blood lipids from oxidative stress", but only if the oil contains ≥5 mg of hydroxytyrosol and its derivatives per 20 g of oil (and the consumer receives ~20 g / day). This emphasizes: the quality of EVOO (phenol content) is not an empty phrase.

How much and what kind of oil was used in the studies

In clinical protocols, doses of 30-60 ml/day for 3-7 weeks, sometimes a single 30 ml for a postprandial response were encountered; in secondary prevention, long-term changes in the diet were studied (CORDIOPREV, PREDIMED). Phenolic "saturation" is important: high-polyphenol oils (≈320-360 mg/kg) gave more pronounced shifts in pressure/inflammation than low-polyphenol oils (≈80-90 mg/kg). At the population level, the "working" benchmark seems to be 20-30 g of EVOO per day in the diet - this is where the best associations with the risk of CV events were recorded.

How to recognize "phenol-rich" oil (practical tips)

• Early harvest/early blending and varietal characteristics often mean more polyphenols (the oil is more bitter and “hot” on the palate).
• Labelling and analysis: Some manufacturers indicate phenols (mg/kg) or emphasize compliance with the EFSA declaration conditions (≥5 mg hydroxytyrosol per 20 g).
• Storage: Light, heat and time "eat" phenols - keep the bottle in the dark, tightly closed. (This principle is discussed in the papers on the stability of phenols and the "lifespan" of the declared declaration.)

What does this mean for practice (without medical recommendations)

The review's findings are consistent with what we know about the Mediterranean diet: EVOO is its "core" and at the same time a carrier of phenols that affect lipid oxidation, endothelium, thromboinflammatory pathways, and blood pressure. For the general reader, this translates into a simple strategy - shift fats in the diet in favor of EVOO, aiming for 20-30 g / day as a daily guideline and choosing high-quality oils (ideally with a confirmed level of phenols). For people with coronary heart disease / metabolic disorders, integrating EVOO with drug therapy and the rest of the lifestyle looks reasonable and safe. But you should not expect a "miracle" without changing your overall diet and habits.

Numbers to Remember

• -2.5…-2.7 mmHg in systolic pressure over 3 weeks with 60 ml/day of high-polyphenol EVOO.
• Optimum consumption is ~20-30 g/day according to Spanish cohorts in relation to the risk of CV events and stroke.
• EFSA quality threshold: ≥5 mg hydroxytyrosol and derivatives per 20 g oil - to declare lipid protection against oxidative stress.

Important Disclaimers and Limitations

The review is qualitative: due to heterogeneity of designs and doses, the authors did not perform a pooled meta-assessment. Many RCTs are short (3-7 weeks), sample sizes are small; the effect is more often seen on surrogate markers (FMD, ox-LDL, CRP) than on “hard” outcomes, although CORDIOPREV showed an advantage of the Mediterranean diet in secondary prevention of a composite of CV events over 7 years. Finally, high-phenolic oils were sometimes associated with a modest increase in LDL - the clinical significance of this shift is unclear and requires observation against the background of the entire diet.

Short checklist

• Focus on high phenolic EVOO and keep it at ~20-30g/day as part of the MedDiet.
• Evaluate the effect not by single tests, but by a package of markers: pressure, FMD, ox-LDL, CRP/IL-6, lipids.
• Remember: oil is part of a pattern, not a stand-alone treatment; medications and BP/LDL goals are the priority.

Source: Ussia S. et al. Exploring the Benefits of Extra Virgin Olive Oil on Cardiovascular Health Enhancement and Disease Prevention: A Systematic Review. Nutrients 17(11):1843, May 28, 2025. https://doi.org/10.3390/nu17111843