Extra virgin olive oil: what the evidence says about the heart

PREDIMED is the reason olive oil sits at the top of most heart-diet advice. Researchers in Spain assigned 7,447 people aged 55 to 80, all at high cardiovascular risk but without heart disease, to one of three diets: a Mediterranean diet with free extra virgin olive oil, a Mediterranean diet with free mixed nuts, or a control diet with advice to cut fat Estruch 2018.

After a median of 4.8 years, a heart attack, stroke or cardiovascular death had occurred in 96 people in the olive oil group (3.8%), 83 in the nut group (3.4%) and 109 in the control group (4.4%). Adjusted for baseline differences, the olive oil diet carried a hazard ratio of 0.69 compared with controlEstruch 2018.

The trial has a history worth knowing. The original 2013 report was withdrawn after the investigators found protocol problems: some household members were enrolled without randomization, and one site assigned groups without randomizing at all. The 2018 republication reanalysed the data without assuming everyone was randomized, and the results were similar after leaving out 1,588 participants whose assignment was in doubt Estruch 2018. That is why this page grades the evidence moderate rather than strong: it is one large trial, in one country, testing a whole diet with olive oil rather than olive oil alone.

FDA does not let food labels make full health claims for olive oil. It allows "qualified" claims, a category for evidence that is promising but not settled. FDA lists a 2004 qualified claim for monounsaturated fat from olive oil and coronary heart disease FDA, and in 2018 it accepted a claim for oils with at least 70% oleic acid, naming olive oil among them FDA.

The approved wording is careful: "supportive but not conclusive scientific evidence suggests that daily consumption of about 1½ tablespoons (20 grams) of oils containing high levels of oleic acid, when replaced for fats and oils higher in saturated fat, may reduce the risk of coronary heart disease." FDA adds that the oil should not increase the total calories you eat in a day FDA.

Every piece of evidence here is about replacement. In the US cohort study, swapping 10 grams a day of margarine, butter, mayonnaise or dairy fat for the same amount of olive oil was linked with 8% to 34% lower risk of death from various causes. Compared with other vegetable oils combined, olive oil showed no clear advantage Guasch 2022. The cohort meta-analysis found the same pattern: olive oil was associated with lower risk, while monounsaturated fat from mixed sources, including meat, was notSchwingshackl 2014.

So the practical step is to cook and dress food with olive oil in place of butter and other solid fats, alongside more vegetables, beans, whole grains and nuts. Pouring extra oil on an otherwise unchanged diet adds calories and is not what the trials tested.

Four cohort studies with 15,784 cases of type 2 diabetes found people with the highest olive oil intake had a 16% lower risk than those with the lowest, though the relationship was not a straight line. In trials in people who already had type 2 diabetes, olive oil lowered HbA1c by 0.27 percentage points more than control diets Schwingshackl 2017. The authors note the finding applies to olive oil as a food, not to any single compound extracted from it. If blood sugar is your concern, see the blood sugar page for other foods with trial evidence.

PREDIMED supplied extra virgin olive oil, the grade pressed without heat or solventsEstruch 2018. It keeps more of the olive's natural compounds than refined "light" or "pure" olive oil, though the trials do not show which of those compounds matter.

A supermarket bottle is all you need. If you want a wider choice of single-origin extra virgin oils, iHerb lists extra virgin olive oils from several producers.