In the landmark PREDIMED trial, adults at high cardiovascular risk who consumed the most extra-virgin olive oil had a 39 percent lower risk of heart attack, stroke, or cardiovascular death compared with those who ate the least.
The Spanish trial followed 7,216 older adults for a median of nearly five years and remains one of the strongest pieces of evidence on olive oil and the heart.
A separate Harvard analysis of more than 92,000 U.S. nurses and health professionals, published in the Journal of the American College of Cardiology in January 2022, put a specific daily target on the finding.
Adults who ate more than 7 grams a day, roughly half a tablespoon, had a 19 percent lower risk of dying from cardiovascular disease over 28 years of follow-up.
Also read: Your brain may be warning you about heart disease 3 to 8 years before it strikes
What the brain data actually shows
The same Harvard cohort was tracked for cause of death from dementia. A 2024 analysis in JAMA Network Open reported that participants consuming more than half a tablespoon a day had a 28 percent lower risk of dying from dementia, including Alzheimer's disease, than those who never or rarely used olive oil.
The 2022 paper found 17 percent lower cancer mortality and 29 percent lower mortality from neurodegenerative disease in the highest-intake group.
These are observational findings and do not prove causation, but the size of the cohort and the 28-year follow-up make the associations difficult to dismiss.
Why olive oil, and not just any fat
Extra-virgin olive oil is rich in plant compounds called polyphenols, including one named oleocanthal.
Also read: Two hours in nature each week may be enough to significantly improve your health
Oleocanthal blocks the same COX enzymes as ibuprofen, giving extra-virgin oil a measurable anti-inflammatory action, though at everyday food doses the effect is modest rather than drug-like.
Refined olive oils lose most of these polyphenols during processing. In PREDIMED, the strongest cardiovascular signal came specifically from extra-virgin olive oil, not from lower-grade oils.
How much is enough
More is not always better. A meta-analysis pooling data from more than 713,000 people found that the risk reduction for cardiovascular events and total mortality largely flattened out at roughly 20 grams a day, about a tablespoon and a half.
Beyond that point, extra olive oil no longer added measurable benefit in the pooled data.
Also read: Hitting the 150-minute exercise target may protect your heart less than you think
The Harvard team also examined substitution rather than addition. Replacing 10 grams a day of margarine, butter, mayonnaise, or dairy fat with olive oil was linked to an 8 to 34 percent lower risk of total and cause-specific mortality.
The practical takeaway is to swap olive oil in for less healthy fats, not to pour it on top of an already fat-heavy diet. Readers on cholesterol-lowering medication or with existing cardiovascular disease should talk to their doctor before making major dietary changes.
Also read: A daily cup of beans may be the simplest longevity habit you are overlooking