Extra virgin olive oil is one of the key ingredients in this diet, but the research on its benefits for heart disease is mixed.

For example, a 2018 review suggests it may help lower inflammation and increase HDL (good) cholesterol. The authors note it may also lower other blood lipids, but not as much as other plant oils.

On the other hand, a 2022 meta-analysis found that each additional 10 grams of olive oil consumed daily had minimal effects on blood lipids.