Heart disease. Olive oil can help lower LDL "bad" cholesterol and maintain levels of HDL "good" cholesterol. It may also help slow the development of plaque in your heart's arteries.
Research suggests that olive oil may protect against heart disease. Death rates from coronary heart disease are low in countries where people use olive oil as their main source of fat. One study found that people who ate the most olive oil had a lower risk of a first heart attack compared to those who ate the least.
Strokes. A 2011 study found that older people who frequently used olive oil had a 41% lower risk of stroke than those who never used it.
Blood Pressure: In one study of people with high blood pressure, a diet heavy in extra-virgin olive oil -- along with slightly lower saturated fat -- lessened the need for blood pressure medicine.
Cancer. Components of olive oil called phenolics may help inhibit cancer in several ways. For example, they may:
Reduce inflammation in the body
Act as an antioxidant (nutrient that helps repair cell damage)
Lead to the death of cancer cells
Lab tests have found anti-cancer effects from several types of phenolics in olive oil.
Some people also use olive leaf to try to treat infections. Research has shown that olive leaf extract may inhibit bacteria and fungi. It may also work against viruses and act as an antioxidant.
Experts recommend getting 25% to 35% of your daily calories from fat, including oil. Most should be in the form of monounsaturated fat such as olive oil.
Optimal doses of olive leaf have not been set for any condition. Quality and active ingredients in supplements may vary widely. This makes it hard to set a standard dose.