Olive oil and Cholesterol and Arteriosclerosis

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.

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.