What are antioxidants and
Oxidation is a process that
occurs not only when oil is being produced, but also inside our own bodies.
Reactions occur continually inside the body, giving rise to the formation of
free radicals (peroxidants). As a rule, free radicals do not cause severe damage
thanks to the protection provided by antioxidants, which help to keep a balance
up to a point. If the balance is spoiled, however, "oxidative stress" occurs,
leading to deterioration of normal cell functions and even cell
Oxidation is a complex, fundamental phenomenon in the process of
cell ageing. Lipid or fat peroxidation tends to be proportional to the number of
double bonds in a compound, explaining why oleic acid shows little
susceptibility to oxidation.
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.
Approximately 1.5% of
olive oil is made up of the unsaponifiable fraction, which contains
antioxidants. Virgin olive oil contains the largest quantities of these
substances and other minor components.
Antioxidants in olive
(alpha-tocopherol), carotenoids and phenolic compounds (simple phenols such as
hydroxytyrosol and complex phenols such as oleuropein) are all antioxidants
whose activity has been demonstrated in vitro and recently in
vivo, revealing further advantages in the prevention of certain diseases and
also of ageing.
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.
Oxidised LDLs are
known to be atherogenic, which is where olive oil steps in because it has a
beneficial, protective effect against LDL oxidation. Moreover, it also
strengthens other cells in the body against the toxic effects of oxidants.
The high antioxidant content of the Mediterranean diet appears to
contribute significantly to its effect on longevity.
are found in fresh fruit and vegetables. Because it is the only oil to be
obtained from a fruit, olive oil retains a host of substances, antioxidants and
vitamins that give it added nutritional value.
The explanation behind
this high content of antioxidants is probably that because the olive is a fruit
that is exposed to the air, it has to defend itself from oxygen. It therefore
synthesises a larger amount of antioxidants, which pass through to the
Virgin olive oil, i.e. olive oil that has not been refined or
industrially treated, is particularly rich in these substances and it has a
strong antioxidant effect, protecting against damage from free radicals
(scavenger activity) and against the formation of cancer.