Olive Oil

Last reviewed October 2026 · Based on 12 studies

Bottom line

Extra virgin olive oil, eaten as part of a Mediterranean diet, is linked to fewer heart events, and a large trial of that diet found fewer major heart events. The trial was withdrawn and re-analysed after randomisation problems, and olive oil alone has not clearly changed cholesterol or blood pressure in pooled trials, so the heart benefit is limited.

What it helps with

A Mediterranean diet with extra virgin olive oil lowered major heart events — Benefit, evidence grade C (Limited). One large trial of a whole Mediterranean diet, withdrawn and re-analysed after protocol deviations, plus observational cohorts; downgraded for indirectness and risk of bias, and cohorts cannot show cause.
Changes cholesterol levels — No effect, evidence grade B (Moderate). Meta-analysis of 33 randomised trials found no significant effect on LDL, HDL, total cholesterol or triglycerides; downgraded once because cholesterol is a surrogate marker.
Improves cholesterol more than low-polyphenol olive oil — Benefit, evidence grade C (Limited). Meta-analysis of 26 trials comparing two olive oils, not olive oil with no oil; heterogeneity for some outcomes; surrogate markers.
Lowers blood pressure — No effect, evidence grade C (Limited). Meta-analysis of 17 trials, 14 on olive oil and 3 on flaxseed oil, found no significant effect; a small crossover trial found a systolic fall in one period only; surrogate marker, and the authors call for longer, larger trials.
Better for LDL cholesterol than butter — Benefit, evidence grade C (Limited). One 4-week trial of 94 people; surrogate marker and short duration.
Lowers the risk of dying early — Benefit, evidence grade C (Limited). Observational cohort meta-analyses only; confounding is likely and cohorts cannot show cause.
Lowers cancer risk — No effect, evidence grade C (Limited). Observational cohort meta-analysis found no significant association; observational only.

What it is

Extra virgin olive oil is rich in plant compounds called polyphenols, and its polyphenol fraction may partly explain the heart effects linked to it [1]. Common olive oil lacks these polyphenols [2].

How it might work

Proposed, and not yet tested directly: polyphenols may reduce the oxidation of LDL cholesterol. A 2019 meta-analysis found high-polyphenol olive oil lowered oxidised LDL and malondialdehyde, a marker of oxidative damage, compared with low-polyphenol oil [1].

What the research says

The largest trial, PREDIMED, assigned 7,447 people at high heart risk to a Mediterranean diet with extra virgin olive oil, a diet with nuts, or a low-fat diet. Over a median of 4.8 years, the olive oil group had a hazard ratio of 0.69 (0.53 to 0.91) for major cardiovascular events [3]. The trial was withdrawn in 2018 after protocol deviations and re-analysed; a 2019 Cochrane review found low-quality evidence of little or no effect on cardiovascular death (HR 0.81, 0.50 to 1.32) and a lower stroke rate (HR 0.60) [4].

In cohort studies, a 2022 meta-analysis found 16% lower cardiovascular disease risk for each extra 25 g a day of olive oil, with heterogeneity between studies [5]. Within PREDIMED, the highest tertile of extra virgin olive oil intake had a hazard ratio of 0.75 (0.60 to 0.94) for a composite of cardiovascular events [2].

Trials of olive oil itself found no significant effect on total, LDL or HDL cholesterol, triglycerides or blood pressure across 33 randomised trials, although insulin and insulin resistance fell [6]. Across 17 trials of olive or flaxseed oil, blood pressure did not change significantly [7]. A 2019 meta-analysis found high-polyphenol olive oil improved total and HDL cholesterol compared with low-polyphenol oil [1].

Cohort analyses found 11% lower all-cause mortality for each extra 25 g a day and no clear link with cancer [5].

Doses used in studies

The PREDIMED report's abstract gives outcome numbers but not the olive oil dose [3]. A three-week crossover trial gave 60 mL a day of high-polyphenol oil (360 mg/kg polyphenols) [8]. A four-week trial gave 50 g a day of olive oil, butter or coconut oil [9]. In the highest intake group within PREDIMED, the average was about 49 g a day [2].

Safety and interactions

Only two trials in a 2019 Cochrane review of Mediterranean-style diets reported side effects, and these were absent or minor [4]. No upper intake limit for olive oil was found in the studies cited here, and the highest intake group in one analysis averaged 49 g a day [2]. None of the trials cited here tested medicine interactions, pregnancy, or people with kidney or liver disease [3] [8] [9]. The main trial enrolled people aged 55 to 80 at high heart risk [3]. People taking medicines or with a heart condition should ask a doctor before changing their diet.

Caveats and open questions

No large, long trial has tested olive oil alone against heart events. The best trial tested a whole diet and was re-analysed after protocol problems [3]. The trials of olive oil itself were short; the polyphenol trial lasted three weeks [8]. Heart results in the cohort meta-analysis varied between studies [5]. A registered trial of extra virgin olive oil and cardiovascular events has not yet started recruiting.