The cardiovascular protective effect is olive oil's most studied health benefit. Major studies like PREDIMED have shown significant results.
Olive oil's monounsaturated fatty acids (especially oleic acid) help lower LDL cholesterol ("bad" cholesterol) and raise HDL cholesterol ("good" cholesterol) levels.
Polyphenols add an additional protective layer: they reduce oxidative stress, inflammation and blood vessel wall damage. The FDA recommends daily 2 tablespoons of olive oil for heart health support.