Consuming more than half a tablespoon of olive oil daily was associated with a 15% lower risk of having any type of cardiovascular disease and a 21% lower risk of having coronary heart disease. Replacing one teaspoon of butter, margarine, mayonnaise or dairy fat with the same amount of olive oil was associated with a 5% lower risk of any cardiovascular disease and 7% lower risk of coronary heart disease in this observational study.
Source: Consuming more olive oil associated with less heart disease in Americans