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Olive Knowledge

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

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, report show 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.

    

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