Learning about extra virgin olive oil > Olive Oil in Cooking
At high temperatures, and in the presence of the atmospheric oxygen, the phenomena of oxidation, which fats undergo even at room temperature, has a marked acceleration. The intensity of the process of oxidation is proportional to the degree of unsaturation of the fat (to its content in mono- and polyunsaturated fats), while its action is countered by the presence of antioxidant substances; only olive oil has a stable reaction to the combined attack of oxygen and high temperatures.
The entity of the alterations suffered by the fats when they are exposed to cooking depends on two other decisive factors:
 The higher the temperature, the more likely it is to have alterations of the fats, which in extreme cases, may be responsible for toxic effects.
Every fat possesses a specific level of tolerance to high temperatures, defined smoke point: beyond that thermal level, glycerol, which with fatty acids forms triglycerides, decomposes to form acrolein, a substance which is extremely dangerous for the liver. One should never exceed this level; it should be remembered that olive oil, with a smoke point among the highest of all oils, tolerates temperatures of up to 200°C.
An even more decisive argument than the thermal level is the duration of cooking time: after 20 minutes’ exposure to not particularly high temperatures we have the first alterations in fats, whereas only after lengthy heating actual toxic effects are produced, with the formation of products of degradation such as cyclical monomers and peroxides; also in these cases olive oil has a much lower degradation index than other vegetable oils.
The Mediterranean diet
In February 1952, when the American professor Ancel Keys landed at Naples with his wife and a car full of laboratory equipment, a suggestion was made to carry out a survey on eating habits which could supply details to be compared with those he had gathered in the United States in relation to the risk of cardiocirculatory diseases. In a few months it was established that the “alimentary regime in Naples was poor in fats and that only rich people suffered from heart attacks.”
A few years later he went to Crete, and there too he ascertained the almost total absence of coronary diseases, despite the fact that the average alimentary regime derived almost 40% of calories from fats.
The famous Seven Countries Study began from this point, a study which compared the diets of 14 sample people, aged between 40 and 59, for a total of 12,000 cases, in seven countries of three continents (Finland, Japan, Greece, Italy, Holland, United States and Yugoslavia).
From 1960 onwards medical studies have compared the daily diet of the subjects under examination with the incidence of ischemic heart disease (infarction and thrombosis), in search of precious clues relative to the best diet for avoiding or reducing the risk of these conditions, which in the Western world represent the main cause of death.
The resulting figures are clear: among the populations of the Mediterranean basin, whose diet is based mainly on paste, fish, fruit and vegetables and who use exclusively olive oil as a condiment, the percentage of mortality due to ischemic heart disease is much lower than among people from countries such as Finland, where the daily diet includes large quantities of saturated fats (butter, lard, milk, red meat).
The conclusions of this study (backed up by other epidemiologic surveys, for example one carried out in Japan, in which the local eating habits are compared with those of Japanese immigrants to Hawaii and the United States who had “westernized” their diet) are indisputable: there is a link between a diet poor in saturated fats and a lower risk of infarction.
Moreover, the life expectancy of Italians and Greeks is on average longer than that of Finns and the Dutch. A Mediterranean type diet is not necessarily “poor”; rather, the calorific contribution of fats is fairly high, but it is represented almost totally by olive oil: on this basis the diet is better balanced than many “slimming diets” offered by publicity as a solution for every problem.
The beneficial effects of olive oil
 Galeno, a Greek doctor who lived in the II Century a.D. and who is considered to be the “father” of medicine, attributed to olive oil therapeutic virtues in fighting the “ills of the belly”, while Dioscoride considered it particularly suitable for use in making up ointments; he also thought it good for the stomach “being a corrector”. Used in beauty care because it prevents the skin from the effects of ageing, the scalp from the formation of dandruff and from the loss of hair, it was in more recent times advised for the treatment of arthritis, gout and rheumatism in general. Modern science recognizes the indisputable merits and virtues of olive oil, however more in the alimentary-medicament field than as a component of medical products. It is considered a natural defence against diseases of the digestive tract, ageing of the bones, cardiovascular diseases, arteriosclerosis and certain types of tumours.
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