Oxidation is a process that takes place not only during the production of oil but also in our own bodies. Reactions which activate the formation of free radicals (peroxides) are continually taking place in our bodies. As a rule, free radicals do not cause significant damage, thanks to the protection provided by antioxidants which help maintain balance up to a point. If this equilibrium is disturbed, however, this leads to “oxidative stress”, which in turn leads to the deterioration of normal cellular functions, and even to the death of cells.
Oxidation is a complex, fundamental phenomenon which is part of the process of cell aging. Lipid or fat peroxidation tends to be in proportion to the number of double bonds in a compound, which explains why oleic acid appears to have low oxidation susceptibility.
Cell membranes contain a large amount of fat and cholesterol and their composition depends on diet. When the diet contains a lot of olive oil, the cells are more resistant to oxidation, they do not deteriorate as much and ageing is slower.
About 1.5% of olive oil is unsaponifiable, and contains antioxidants. Virgin olive oil contains the largest quantities of these substances, as well as other secondary elements
The antioxidants in olive oil
Vitamin E (alpha-tocopherol), carotenoids and phenolic compounds (simple phenols, such as hydroxytyrosol and complex phenols such as oleuropein) are all antioxidants whose activity has been proven in vitro, but also more recently in clinical trials which revealed additional roles in the prevention of certain diseases and the delaying of aging.
The phenolic content of olive oils varies according to the climatic conditions in the producing area, when the olives are harvested and how ripe they are when picked. Oil production and storage methods also have an influence. Phenols have countless biological properties, for instance hydroxytyrosol inhibits platelet aggregation and it is anti-inflammatory and oleuropein encourages the formation of nitric acid, which is a powerful vasodilator and exerts a strong anti-bacterial effect.
Oxidized LDL-cholesterol is known to be potentially damaging to arteries. This is where olive oil comes into its own as it has a beneficial, protective effect against the oxidation of LDL-cholesterol. In addition, it strengthens other cells of the body against the toxic effects of oxidants.
The high content of antioxidants in the Mediterranean diet seems to contribute significantly to the longevity of Mediterranean peoples.
Antioxidants are found in fresh fruits and vegetables. As it is the only oil produced from fruit, olive oil retains many ingredients, antioxidants and vitamins, which give it extra nutritional value. The explanation behind this high antioxidant content probably lies in the fact that, because the olive is a fruit and is exposed to air, it must be protected from oxygen. Therefore, it synthesizes a large number of antioxidants, which are also found in olive oil.
Virgin olive oil, i.e. oil that is made without chemicals or industrial processing, is particularly rich in these substances and has a strong antioxidant effect, providing protection against damage caused by free radicals (cleansing action) as well as against the onset of cancer. www.internationaloliveoil.org