There's new proof that olive oil is good for you.
But you get what you pay for, with high-quality extra virgin varieties far more likely to prevent heart attacks and stroke than cheaper processed types.
Fifty grams or 3.5 tablespoons a day are ideal for a person at high risk of cardiovascular disease, says Spanish dietician Marta Guasch-Ferre, who is in Australia to present the findings of a major research project.
The risk of cardiovascular disease is reduced by 10 per cent for every two teaspoons, according to her study, which was published on Wednesday in the journal BMC Medicine.
The oil should make up around 10 per cent of the calories in a diet rich in legumes, fruit, vegetables, nuts, seeds, fish and unprocessed white meat.
The oil is better raw, but heat is not a major issue, she says.
Low-fat dairy, nuts and fruit can be used for a healthy desert, but sugar, refined carbohydrates and animal fats should be limited.
"Different types of olive oil are associated with different levels of risk reduction," said Ms Guasch-Ferre, a speaker at the World Forum for Nutrition Research, being hosted in Brisbane by the Dietitians Association of Australia (DAA).
Extra virgin or virgin oil is extracted gently from ripe olives and is far more protective than processed types.
"When olive oil is processed and refined it loses some of its beneficial properties," said Ms Guasch-Ferre, whose group re-analysed death, diet and disease statistics among 7216 people aged 55 to 80 years who are part of a Spanish Mediterranean diet study known as PREDIMED.
All the people in the study are considered to be at high risk of cardiovascular disease and are tracked for an average of five years.
Another study by Ms Guasch-Ferre's group shows longevity benefits of polyphenols found in grape skin, red wine, olives, virgin olive oil, flax seed, sesame seed and whole grains.
The findings suggest people who have a high risk of heart disease can improve their health by making small dietary and lifestyle changes, said DAA CEO Claire Hewat.