Olive oil, rich in monounsaturated fatty acids, is a major component of the Mediterranean diet.
Monounsaturated fatty acids (MUFAs) are considered a healthy dietary fat, as opposed to saturated fats and trans fats.
This MNT Knowledge Center feature is part of a collection of articles on the health benefits of popular foods.
What is olive oil?
Olive oil is a fat obtained from the fruit of the Olea europaea (olive tree), a traditional tree crop of the Mediterranean region, where whole olives are pressed to produce olive oil.
The oil is used in cosmetics, medicine, cooking and soaps, and was also used as a fuel for traditional lamps. Although originating in the Mediterranean countries, today it is used worldwide.
Greece has the highest olive oil intake per person in the world. Greeks consume, on average, 24 liters per-person-per-year, according to the North American Olive Oil Association (resource no longer available at www.aboutoliveoil.org)1. Spaniards and Italians consume about 15 and 13 liters-per-person-per year, respectively.
Possible health benefits of olive oil
Over the last 50 years, there have been thousands of studies examining the health benefits of olive oil. Below are some examples:
Olive oil and the cardiovascular system
In 2010, more than 45% of global olive oil production came from Spain
Olive oil is the main source of dietary fat in the Mediterranean diet, which is associated with a low death rate from cardiovascular diseases compared to other parts of the world.
Maria-Isabel Covas, at the Parc de Recerca Biomèdica de Barcelona, Spain, carried out an extensive review of studies that had focused on the biological and clinical effects of olive oil.
The study was published in the journal Pharmacological Research2.
The study found that people who regularly consume olive oil are much less likely to develop cardiovascular diseases, including hypertension (high blood pressure), stroke, and hyperlipidemia (high blood cholesterol and triglyceride levels).
Covas concluded "The wide range of *anti-atherogenic effects associated with olive oil consumption could contribute to explain the low rate of cardiovascular mortality found in Southern European Mediterranean countries, in comparison with other western countries, despite a high prevalence of coronary heart disease risk factors."
*Anti-atherogenic means preventing the hardening of the arteries and the development of atherosclerosis.
Frying with olive oil and heart disease risk
People who regularly eat foods fried in olive oil do not have a higher risk of heart disease or premature death, researchers at the Autonomous University of Madrid in Spain reported in the BMJ (British Medical Journal).
In this study, Professor Pilar Guallar-Castillón and colleagues surveyed 40,757 adults aged from 26 to 69 years over an 11-year period. They focused on the people's cooking methods and dietary habits. None of the participants had heart disease when the study started.
The team defined fried meals as food that had only been prepared by frying it. Participants were also asked whether their fried food was sautéed, battered or crumbed.
The researchers concluded:
"In a Mediterranean country where olive and sunflower oils are the most commonly used fats for frying, and where large amounts of fried foods are consumed both at and away from home, no association was observed between fried food consumption and the risk of coronary heart disease or death."
Olive oil may help prevent stroke
Dr. Cécilia Samieri, from the University of Bordeaux and the National Institute of Health and Medical Research (INSERM) in Bordeaux, France, and colleagues reported in the journal Neurology that olive oil may prevent strokes in older people.
The team found that older people who regularly used olive oil for cooking and salad dressing or with bread had a 41% lower risk of stroke, compared with their counterparts who never consumed it.
Dr. Samieri said, "Stroke is so common in older people and olive oil would be an inexpensive and easy way to help prevent it."
Depression risk and olive oil
People whose diets are high in trans fats - fast foods and mass-produced foods like pastries - may have a higher risk of depression, compared with those whose diets are rich in mono- and polyunsaturated fats.
According to a study carried out at the University of Las Palmas de Gran Canaria in Spain and published in PLoS ONE, olive oil appears to have a slight protective effect regarding depression risk.
Dr. Almudena Sánchez-Villegas and colleagues added that their findings stood even after taking into account people's overall diet, physical activity and lifestyle.
The research team gathered and analyzed data on 12,000 volunteers over a period of 6 years. Their average age at the start of the study was 37.5 years. They had all regularly completed a 136-item questionnaire which had information on their dietary habits, lifestyle, and physical and mental health.
The investigators counted the number of people with depression at the start of the study and then again during each follow-up. Cases of depression had to be those clinically diagnosed by a doctor.
The study authors found that when they compared the volunteers who consumed trans fats regularly with individuals whose dietary fat consisted primarily of olive oil, the trans fat consumers had a 48% higher risk of developing depression.
The amount of trans fat consumed was directly related to depression risk - the more they ate, the higher the risk.
Olive oil may reduce breast cancer risk
A team of scientists at the Universitat Autonoma de Barcelona in Spain found a key mechanism by which virgin olive oil protects the body against breast cancer, in contrast to other vegetable oils.
The researchers decoded a complete cascade of signals within the cells of breast tumors that are activated by virgin olive oil. They concluded that the oil reduces the activity of p21Ras, an oncogene, prevents DNA damage, encourages tumor cell death, and triggers changes in protein signaling pathways.
The team found that while corn oil - which is rich in n-6 polyunsaturated fatty acids - increased the aggressiveness of tumors, virgin olive oil had the opposite effect.
They demonstrated that virgin olive oil is linked to a higher incidence of benign (non-cancerous) breast tumors.
Olive oil helps maintain healthy cholesterol levels
A Japanese study published in the Medical Science Monitor3 showed that LDL-cholesterol mean concentrations were lowered in 28 outpatients who were given olive oil supplements once a day for six weeks.
LDL (low density lipoprotein) is often referred to as "bad cholesterol". The "good cholesterol" is called HDL (high density lipoprotein).
The study authors concluded "These results point to an overwhelmingly beneficial influence of olive oil on the lipoprotein spectrum."
On the next page we look at some of the other possible health benefits of olive oil, including helping prevent alzheimer's disease and acute pancreatitis and protecting your liver. We also look at the nutritional breakdown of olive oil.