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Digestion
Infants
Ageing
Arteriosclerosis and Cholesterol
Frying with olive oil
An important
aspect: Health Benefits
The following
is based on information has been provided by the IOOC.
Consumers have growing access to ever more comprehensive product information. Often this
is supplied in publicity by the companies producing the product, in which case it is
always subjective. Other times the sources are more objective, such as the media,
reports by consumer organizations, and scientific or technical studies, although this
last type of information takes longer to reach the general public. Consumers pay more
attention to food products because the consequences they have can be beneficial or
harmful to health.
Any information on olive oil would be incomplete if it did not take into account this
important facet, especially when the beneficial effects of consuming olive oil are
backed by lengthy, painstaking scientific research. The fat and oil sector is very
complex. Fats and oils have a common denominator which is their energy value - 9
calories per gram - but the metabolism of each one or each group differs greatly from
the rest. Olive oil contains a series of compounds that are very beneficial to most
functions of the human body. Highly-qualified members of the scientific profession now
discuss these on the basis of studies and experiments.
Olive oil's biological and therapeutic value is related in many aspects to its chemical
structure. The first aspect is its triglyceride composition, made up of fatty acids.
Olive oil has a prevalence (54 - 83%) of monounsaturated fat, oleic acid principally,
while animal fats are fundamentally made up of saturated fatty acids and seed oils of
polyunsaturated (50 - 72% in soybean and sunflower oil). Monounsaturated fatty acids are
much more stable than polyunsaturated ones vis-à-vis the oxidative processes that, if
produced, lead to rancidity. Olive oil also has a low percentage of polyunsaturated fats
varying between 3.5 and 22.5%. These are essential fatty acids that cannot be
synthesized by the body. However, a normal diet covers the essential fatty acid
requirements of both adults and infants and has the best linoleic acid to linolenic acid
ratio. Both olive oil and olive-pomace oil have an identical glyceridic structure, which
means they share the same beneficial properties.
Secondly, olive oil's beneficial properties lie in its minor components. The most
salient ones are the tocopherols, among them alpha-tocopherol which acts as vitamin E
and carotene as provitamin A, and the polyphenols. All of these components have a major
antioxidant function and are closely connected with virgin olive oils because refining
processes alter and partially remove them in the other types.
Olive oil and the digestive system
According to Char bonnier, olive oil is the oil that is best tolerated by the
stomach due to its high oleic acid content.
The tone of the sphincter which separates the stomach and esophagus and which impedes
the reflux of gastric juices is less affected by olive oil. Butter is the least
tolerated fat, while sunflower oil has intermediate effects. Gastric emptying time is
affected in the same way by these three types of fat.
Since ancient times olive oil has been described as having a beneficial effect on
hyperchlorohydric gastritis and gastroduodenaal ulcers, which is attributed to its
protective function. When animal fats were replaced by olive oil in the diets of
patients suffering from ulcers the result was a reduction of lesions in 33% of the cases
and cicatrlzatlon in 55% (Taits). However, prescribing olive oil does not eliminate the
need for drugs therapy.
Two tablespoons of olive oil taken in the morning on an empty stomach appear to have a
positive effect on chronic constipation.
Olive oil has a very positive effect on atony of the gallbladder in that It has a more
acute, gentle and prolonged action than prescribed drugs and other foods that have
similar effects It inhibits hepatobiliary secretion during gallbladder emptying time and
is therefore a pure cholagogue and can be used as a medicinal food. This effect has been
known since ancient times and has been confirmed recently in numerous studies.
Cholelithiasis (gallstones) is a wide spread illness. It is related to the metabolism of
fats and is found to a greater extent in more economically developed countries. Overall
excess dietary intake, particularly of saturated fats and cholesterol, leads to
increased biliary excretion of cholesterol and a reduction in bile acids and lecithin.
It appears that high plasma cholesterol levels increase the risk of lithiasis because
they simultaneously raise the fraction of cholesterol transported by the low-density
lipoproteins (LDL) that inhibit the hepatic synthesis of cholesterol. It is also true,
however, that the cholesterol transported by the high-density lipoproteins (HDL) is more
easily metabolized into bile acids than it is excreted with bile, When a patient with a
high cholesterol level undergoes treatment, plasma cholesterol has to be lowered by
increasing its elimination via the biliary tract. For that reason, the majority of
experts agree that foods rich in saturated and polyunsaturated fats play a possible role
in the formation of calculi, while monounsaturated-rich olive oil would not appear to
play such a role. Olive oil can be said to have a protective effect against the
formation of gallstones, due to the way in which it activates bile flow and increases
HDL, as well as to its balanced saturates: polyunsaturated ratio and its high content of
monounsaturated. Messini and Cairella have demonstrated that there is a lower incidence
of biliary calculi in areas of Italy where olive oil consumption is higher.
Olive oil in infancy
Fat intake is important to both the new-born baby and the weaned infant; even more
important is the appropriate intake of essential fatty acids. Breast-fed babies receive
4 - 5% of their calories in the form of polyunsaturated acids, while babies fed on cow's
milk receive substantially less. Low linoleic acid intake can delay growth and produce
skin, hepatic and metabolic disorders. Seed oils, which are rich in polyunsaturates, are
not recommended in large quantities for children because it is not advisable to lower
their cholesterol level and because these oils promote peroxidative phenomena,
especially in youngsters with low vitamin E reserves. Hence, it is important to strike a
balance between the dietary supply of linoleic and linolenic acids because too much of
the former can cause disorders of the nervous system. In his comparison of the effects
of olive oil, sunflower oil and saturated fats on growing rats, Galli detected
modifications in the structural lipids of the brain and liver among the groups treated
with saturated fats and sunflower oil. There were none, however, in the group treated
with olive oil. Olive oil provides a relatively low amount of essential fatty acids but
has a balanced linoleic:linolenic ratio similar to that found in breast milk.
As regards the influence of olive oil on bone mineralization and development, a study by
Laval-Jeantet demonstrates the need for fats. The most positive effects are obtained
with the intake of oleic glycerides to which a minimum amount of polyunsaturates is
added, and so the best diets for this purpose are those containing olive oil.
Olive oil and old age
From the very outset, food provides human beings with the energy necessary for the
renewal and continuation of life. Each cell inherits a program that dictates its
biological activity and that can be repeated an unlimited number of times. Successive
repetition, however, produces errors that are corrected at first, but which over time
become consolidated and give rise to incorrect information to which other errors are
added. A diet rich in polyunsaturated fatty acids can lead to peroxidative phenomena,
which expose cells to this production of errors. On the other hand, the presence of
antioxidant substances, such as vitamin E, provides a defense mechanism. Mice fed on
olive oil have a longer life expectancy than those fed on sunflower and corn oil. This
is explained by the better ratio between vitamin E and polyunsaturated fatty acids in
olive oil. When applied to man, this research makes for caution in the indiscriminate
use of polyunsaturated-rich oils and leads to a preference for olive oil over other
dietary fats because of its balanced content of linoleic acid, linolenic acid and
anti-oxidant substances.
In a study on skin changes over time, Pinkey reported that people on a diet consisting
of more than 10% polyunsaturates showed signs of aging. 60% of the cases had skin
lesions removed that were suspected of being malignant.
Bone calcification is another problem common in the elderly. Olive oil seems to have a
positive effect, which appears to be dose-dependent, because the more olive oil ingested
the better the bone mineralization obtained. The explanation might lie in the large
amount of oleates in the structural lipids of bones. According to French researchers,
olive oil would appear to be necessary during growth and later in adulthood to avoid
calcium loss.
Old age brings with it reduced digestive capacity and poor absorption of nutrients,
especially of vitamins and mineral salts. Olive oil has the best characteristics as
regards digestibility and absorption and has a mild laxative effect. Whether consumed
cooked, fried, or better yet raw, in order to make the most of its vitamin and
anti-oxidant content, olive oil helps make food more appetizing and aids digestion.
Olive oil and Arteriosclerosis and Cholesterol
Arteriosclerosis is one of the most widespread diseases in industrialized countries
in which it is the leading cause of death. Together with genetic predisposition, there
are other risk factors that cause the lesion to appear or become aggravated: smoking,
arterial hypertension and hypercholesterolemia. Additional contributing factors are age,
sex (male), diabetes, gout, a high triglyceride level, oral contraceptives and physical
inactivity.
Cholesterol belongs to the sterol group and is a lipid that is abundant in animal
tissue, insoluble in water and soluble in organic solvents. It forms part of cell
membranes and in many cases constitutes a stable complex with phospholipids. In the
body, cholesterol serves as the basis for the synthesis of other steroids involved in
important processes such as the formation of bile acids that emulsify dietary fats so
that they can be absorbed by the intestinal epithelium, or in the regulation of vitamin
D.
The incidence of arteriosclerosis is closely linked to dietary habits. A diet rich in
animal fats tends to raise plas-ma cholesterol. On the other hand, vegetable oils rich
in polyunsaturated acids have an anti-atherogenic, protective action against
cholesterol, and lower cholesterol levels.
As previously mentioned not all plasma cholesterol is atherogenic. The cholesterol
transported by the low-density lipoproteins (LDL-cholesterol) is particularly so,
whereas the cholesterol carried by the high-density lipoproteins (HDL-cholesterol)
appears to have a protective effect since their function is to eliminate free
cholesterol in the cells and to esterify and carry it to the liver where it is emptied
with the bile.
Numerous studies have confirmed a negative correlation between plasma HDL levels and
arteriosclerosis and a positive correlation between HDL and a longer life expectancy.
Any treatment of hypercholesterolemia must begin by lowering saturated fat intake. The
suppression of these fats produces a reduction in plasma cholesterol double that
obtained through the addition of an equal amount of polyunsaturated-rich lipids (Keys,
Grande Covian et al.). If the substitution is with olive oil, which is rich in
monounsaturates, the total cholesterol level is approximately equal to that obtained
through the reduction of saturated fat intake. The positive effect of monounsaturated
fats is not limited to a similar substitution effect as for polyunsaturated fats. It
also increases HDL cholesterol and helps protect against coronary mortality. A
comparative study of deaths from coronary disease in 10,000 men has indicated that at
the same plasma cholesterol levels, the risk of developing this type of disease was
approximately the same in American and Finnish men, while it was much lower in
Mediterranean men who consumed a high percentage of olive oil among other fats.
When eaten in excess, polyunsaturate-rich vegetable oils peroxidize easily and for that
reason can become atherogenic. This is a possible cause of endothelial lesions and
platelet hyperaggregation.
A fitting conclusion to this chapter is to point out that the most important step in the
prevention of arteriosclerosis is to lower animal fats - visible and invisible - and to
replace them by monounsaturated-rich olive oil, which also contains a balanced amount of
polyunsaturated adequately protected by anti-oxidants like alpha-tocopherol or
polyphenols. This dietary approach, which has been confirmed by experimental and
epidemiological research, will permit rational disease prevention and satisfactory
control of plasma cholesterol, without the risk of undesirable side effects.
Olive oil and frying
To make food more appetizing, man uses cooking methods like boiling, baking, smoking and
frying, with the highest temperatures being reached during frying.
The temperature inside fried food remains almost constant at 100 degrees C until its
water content evaporates. At that point the hot oil can penetrate. The food cooks
quickly and the loss of nutritional value is lesser than with other cooking methods,
according to studies by Varela. A crust forms on the outside as a result of the
reaction with the hot oil, which coagulates proteins and caramelizes the glycides. Less
fat is consumed than with other cooking methods, as the oil is not absorbed by the food.
Fats are subjected to auto-oxidative phenomena that are accelerated as temperatures
rise. These phenomena are heightened by the degree of un-saturation of the fat and the
presence of pro-oxidant substances, while they are checked by antioxidants. Some of the
products of deterioration formed are volatile and easily eliminated; others (polymers)
are poorly absorbed and some of those that remain can be toxic and can affect different
organs and detract from the nutritive value of the food.
Animal fats, which have a low degree of un-saturation, do not contain antioxidants and
soon undergo auto-oxidation. Seed oils are highly unsaturated and oxidize rapidly. On
the contrary, olive oil is very stable because of its intermediate degree of
un-saturation and the anti-oxidants if contains. Besides being affected by the type of
fat, deterioration is related to the temperature reached, heating time, type of food
involved, and the presence of catalysts.
Fedeli has demonstrated the stability of olive oil at high frying temperatures, and
Varela has proven that food digestibility is not modified by frying in olive oil,
not even when the same oil was used 10 times over to fry meat and sardines. This
research would appear to indicate that olive oil is the oil best suited to frying owing
to its higher resistance to oxidative deterioration.
To sum up this entire chapter, we can conclude that owing to its fatty acid structure,
Its content in vitamin E and other anti-oxidants, its balanced contents of other
components, and its aroma and flavor, olive oil is the oil that is best suited to human
consumption -whether raw or cooked - and has a protective effect on human health. |