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.
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. Still, there is very little evidence supporting the use of olive leaf extracts, compared with the many studies supporting the consumption of olive oil and its effect on health.
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.