Olive oil and Cardiovascular disease:
olive oil lowered serum cholesterol without lowering HDL-cholesterol, which plays a protective, anti-atherogenic role by encouraging the elimination of LDL-cholesterol
olive oil also has a preventive effect on thrombosis and platelet aggregation.
Cardiovascular diseases are the top cause of death in the industrialised world. A host of studies have documented that arteriosclerosis is closely linked to eating habits, lifestyle and some aspects of economic development. The progression of arteriosclerosis depends on many factors: the most important ones are high blood cholesterol, high blood pressure, diabetes and cigarette smoking.
Olive oil and arteriosclerosis:
Arteriosclerosis is the condition in which cholesterol-rich patches (known as atheromas) deposit on the walls of the arteries. This stops blood from reaching the tissues and obstructs the functioning of vital organs, such as the heart and brain.
When the heart is affected, arteriosclerosis causes angina and heart attack and it increases the risk of sudden cardiac death. When the brain is attacked, cerebral thrombosis occurs, leading to muscular paralysis, loss of cognitive capacity and the risk of dementia. The aorta and leg arteries may also be damaged, causing pain and difficulty in walking and the risk of necrosis and gangrene.
When a fatty patch bursts, for instance because of a rise in blood pressure, the small arteries in the patch also burst. This triggers a response where certain cells found in blood, known as platelets or thrombocytes, join together to form a thrombus or blood clot.
The blood clot travels through the arteries, but when it is larger than the vessel it causes blockage. Because blood cannot get through, the tissue or organ dies.
It has been demonstrated that olive oil has an effect in preventing the formation of blood clots and platelet aggregation. It has been observed that by avoiding excessive blood coagulation, olive-oil-rich diets can attenuate the effect of fatty foods in encouraging blood clot formation, thus contributing to the low incidence of heart failure in countries where olive oil is the principal fat consumed.
Olive oil and cholesterol:
Cholesterol is a fatty substance contained in foods of animal origin. Diets containing a large amount of animal fats raise blood cholesterol level, which is one of the chief risk factors of cardiovascular disease.
Fats (triglycerides) and cholesterol are transported in the blood by lipoproteins. The cholesterol bound to low-density lipoproteins [very low-density lipoproteins (VLDL) and low-density lipoproteins (LDL)] is atherogenic, damaging the vessel walls. In subsequent stages, this may lead to acute heart attack. Such cholesterol is known as "bad cholesterol". In contrast, the cholesterol bound to high-density lipoproteins (known as HDL-cholesterol) is called "good cholesterol" because it provides protection against the onset of cardiovascular diseases. The high-density lipoproteins remove free cholesterol from the cells, then esterifying it and transporting it to the liver where it is eliminated with bile.
Olive oil lowers the levels of total blood cholesterol, LDL-cholesterol and triglycerides. At the same time it does not alter the levels of HDL-cholesterol (and may even raise them), which plays a protective role and prevents the formation of fatty patches, thus stimulating the elimination of the low-density lipoproteins.
The beneficial effect of olive oil consumption with regard to cardiovascular disease has been demonstrated in primary prevention, where it reduces the risk of developing the disease, and in secondary prevention, where it prevents recurrence after a first coronary event.
At present, research is revealing the effectiveness of the Mediterranean diet in the prevention of secondary coronary events and the positive influence of olive oil on the depression associated with such events and on mood. These findings are very important in view of the high incidence of depression in the modern-day world and the great risk it poses in recurrent heart disease.
The antioxidant properties of Olive oil:
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 death.
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.
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 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.
These antioxidants 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 oil.
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.
The minor components present in its unsaponifiable fraction (vitamins and antioxidants): The polyphenols (essantialy the hydroxytyrosol) in virgin olive oil may function in vivo as protective antioxidants by exerting a protective effect against LDL oxidation; it is well known that oxidised LDLs are atherogenic whereas normal ones are not.
Important antioxidant role for this compound, which has important implications in the prevention of arteriosclerosis and its main complication (myocardial infarction and stroke).
The hydroxytyrosol is responsible for the antinflammatory and chemopreventive effects of olive oil at the intestinal level, and can induce apoptosis.
Frying with olive oil:
Frying is one of the few characteristics common to the entire Mediterranean area, be it European, Asian or African, and to the three religions practised, Christian, Muslim and Jewish. It is one of the oldest methods in existence of cooking food.
Recent investigations have shown that frying is beneficial to the organism, particularly from the physiological point of view. Because of this, it has extended to areas where formerly it was not as popular. Whether the food fried is digested easily or lies heavily on the stomach depends to a great extent on the type of oil used, the temperature of the oil and the manner in which the food was fried. Studies undertaken on healthy subjects and patients with gastroduodenal problems (gastritis, ulcer, liver and biliary complaints) have shown that there is no relationship between food fried in olive oil and these illnesses.
The alteration undergone by vegetable oils when heated for frying is quicker and more atty acids (seed oils), and the higher the initial acidity of the oil (it is more stable if it has a high content of natural antioxidants - vitamin E). This alteration also varies according to temperature and length of time heated, number of times used, manner of frying (in continuous frying it changes less), and the type of food being fried (frying fish, especially oily fish, increases the polyunsaturated acid content of the oil, facilitating its decomposition).
Olive oil is ideal for frying. In proper temperature conditions, without over-heating, it undergoes no substantial structural change and keeps its nutritional value better than other oils, not only because of the antioxidants but also due to its high levels of oleic acid. Its high smoking point (210ºC) is substantially higher than the ideal temperature for frying food (180ºC). Those fats with lower critical points, such as corn and butter, break down at this temperature and form toxic products.
Another advantage of using olive oil for frying is that it forms a crust on the surface of the food that impedes the penetration of oil and improves its flavour. Food fried in olive oil has a lower fat content than food fried in other oils, making olive oil more suitable for weight control. Olive oil, therefore, is the most suitable, the lightest and the tastiest medium for frying.
It goes further than other oils, and not only can it be re-used more often than others, it also increases in volume when reheated, so less is required for cooking and frying.
The digestibility of heated olive oil does not change even when re-used for frying several times.
Olive oil should not be mixed with other fats or vegetable oils and should not generally be used more than four or five times.
The oil used for frying should always be hot; if it is cold the food will soak up the oil.
There should always be plenty of oil in the pan when deep frying. If only a small amount is used, not only will it burn more easily but the food being fried will be undercooked on top and overcooked on the bottom.
When heated, olive oil is the most stable fat, which means it stands up well to high frying temperatures. Its high smoking point (210º C) is well above the ideal temperature for frying food (180º C). The digestibility of olive oil is not affected when it is heated, even when it is re-used several times for frying.
Olive oil is more resistant to heat than any other fat so it is the best for frying
olive oil can be re-used for frying without undergoing hydrogenation or isomerisation processes that cancel out its beneficial effects on lipid metabolism. It is the lightest and tastiest fat for frying
Olive oil and blood pressure:It has not yet been clearly established what elements of the Mediterranean diet are responsible for its effects in reducing blood pressure. It has been demonstrated, however, that the addition of olive oil to a diet that is not changed in any other way has a clear lowering effect on blood pressure, which seems to be specific to this oil. Regular consumption of olive oil decreases both systolic (maximum) and diastolic (minimum) blood pressure.
There is recent evidence that when olive oil is consumed the daily dose of drugs needed to control blood pressure in hypertensive patients can be decreased, possibly because of a reduction in nitric acid caused by polyphenols
Olive oil and diabetes:
An olive-oil-rich diet is not only a good alternative in the treatment of diabetes; it may also help to prevent or delay the onset of the disease. How it does so is by preventing insulin resistance and its possible pernicious implications by raising HDL-cholesterol, lowering triglycerides, and ensuring better blood sugar level control and lower blood pressure. It has been demonstrated that a diet that is rich in olive oil, low in saturated fats, moderately rich in carbohydrates and soluble fibre from fruit, vegetables, pulses and grains is the most effective approach for diabetics. Besides lowering the "bad" low-density lipoproteins, this type of diet improves blood sugar control and enhances insulin sensitivity.
These benefits have been documented in child and adult diabetes.
Olive oil significantly improves cell glucose utilisation and lowers triglycerides, and it is more pleasing to the palate than a high-carbohydrate diet containing the same amount of fibre
Olive oil and cancer:
Epidemiological studies suggest that olive oil exerts a protective effect against certain malignant tumours (breast, prostate, endometrium, digestive tract, …).
A number of research studies have documented that olive oil reduces the risk of breast cancer. Eating a healthy diet with olive oil as the main source of fat could considerably lower cancer incidence. The reason is that the cell mutations caused by cancer are partly due to toxins which, when consumed through the diet, attack DNA. On passing through the liver, these toxins produce free radicals that then attack DNA. To combat such free radicals, the body needs vitamins and antioxidants like those contained in olive oil.
It has also been reported that an olive-oil-rich diet is associated with reduced risk of bowel cancer. The protective effect of olive oil is irrespective of the amount of fruit and vegetables eaten in the diet.
Recent studies have demonstrated that olive oil provides protection against cancer of the colon. Lately, research has been looking into the metabolic implications of fats, more specifically the protective role of olive oil in chronic liver disease and in the disorder of the intestines known as Crohn's disease. Results point to beneficial effects of olive oil on pre-cancerous lesions. After analysing three types of diet, research scientists arrived at various conclusions. The olive oil diet reduced the number of cancerous lesions; the number of tumours that developed was clearly and significantly low; and the tumours were less aggressive and had a better prognosis.
This beneficial effect could be related to oleic acid, the predominant monounsaturated fatty acid in olive oil. It has been observed that this fatty acid lowers the production of prostaglandins derived from arachidonic acid, which in turn plays a significant part in the production and development of tumours.
However, it is not excluded that other constituents of olive oil, such as antioxidants, flavonoids, polyphenols and squalene may also have a positive influence. Squalene is believed to have a favourable effect on the skin by reducing the incidence of melanomas.
Olive oil also adds to the taste of vegetables and pulses whose benefits in cancer prevention have been amply proved.
Some very promising, current research is centred on the protection provided by olive oil against child leukaemia and various cancers, such as oesophageal squamous cell cancer.
Much has still to be discovered about how olive oil affects cancer and concrete data are still lacking on the mechanisms behind the beneficial role it plays in the prevention or inhibitionof the growth of different types of cancer. However, according to the information available at present, olive oil could actsimultaneously during the different stages involved in the process of cancer formation.
Olive oil and ageing
Olive oil is rich in various antioxidants (vitamin E, polyphenols, …) which play a positive, biological role in eliminating free radicals, the molecules involved in some chronic diseases and ageing, and in extending life expectancy, which has been demonstrated in several epidemiological studies.
Many ageing-related diseases are influenced by diet, in particular osteoporosis and deteriorated cognitive function.
Osteoporosis is a reduction in bone tissue mass that increases the risk of fractures. There are two types. Type I occurs in middle-aged, post-menopausal women and type II in the elderly.
Olive oil and osteoporosis:
Olive oil appears to have a favourable effect on bone calcification, and bone mineralisation is better the more olive oil is consumed. It helps calcium absorption, thereby playing an important part during the period of growth and in the prevention of osteoporosis.
Olive oil and cognitive functions
Olive-oil-rich diets may prevent memory loss in healthy elderly people. Less possibility of suffering age-related cognitive decline has been observed in a study conducted on elderly people administered diets containing a large amount of monounsaturated fats, the case of olive oil particularly.
Exactly how large quantities of these fats prevent cognitive decline is not known. However, this effect is believed to occur because the monounsaturated fatty acids may help to maintain the structure of the brain cell membranes since the demand for these acids appears to grow during ageing.
The same study observed that the quantity of olive oil consumed was inversely proportional to age-related cognitive decline and memory loss, dementia and Alzheimer's disease.
Olive oil is rich in vitamin E, which plays a positive biological role in removing free radicals, which are the molecules involved in certain chronic diseases and in the ageing process. Hence, olive oil is believed to play a part in increasing life expectancy.
Olive oil consumption provides protection against deterioration of the cognitive functions related to ageing and age-related memory loss.
Olive oil and the digestive system:
Olive oil is the fat that is best digested and absorbed; it has excellent properties in this respect and a mild laxative effect that helps to combat constipation
As soon as we eat olive oil it has a number of effects all the way along the digestive system.
As far back as in ancient times it was recommended for assorted digestive disorders, and its beneficial properties are now being corroborated by epidemiological studies and a wealth of scientific data.
Olive oil and the stomach:
When olive oil reaches the stomach it does not reduce the tonus of the muscular ring or sphincter at the base of the oesophagus. Because of this, it reduces the risk of the flow or reflux of food and gastric juice up from the stomach to the oesophagus.
Olive oil also partially inhibits gastric motility. As a result, the gastric content of the stomach is released more slowly and gradually into the duodenum, giving a greater sensation of "fullness", and favouring the digestion and absorption of nutrients in the intestine.
Olive oil and the hepato-biliary system:
One of the effects of olive oil on the hepato-biliary system is that it is a cholagogue, ensuring optimal bile drainage and full emptying of the gall bladder. Another effect is that it is cholecystokinetic, i.e. it stimulates the contraction of the gall bladder, which is extremely helpful in the treatment and prevention of disorders of the bile ducts. It stimulates the synthesis of bile salts in the liver and it increases the amount of cholesterol excreted by the liver.
In short, owing to its beneficial effect on the muscle tone and activity of the gall bladder, olive oil stimulates the digestion of lipids, because they are emulsified by the bile, and it prevents the onset of gallstones.
Olive oil and the pancreas:
When consumed, olive oil produces a small amount of secretion by the pancreas, making this organ "work" little, but efficiently and enough to carry out all its digestive functions. Olive oil is recommended in diseases where pancreatic function has to be maintained, such as pancreas failure, chronic pancreatitis, cystic fibrosis, malabsorption syndromes, etc.
Olive oil and the intestines :
Owing to the sitosterol it contains, olive oil partially prevents cholesterol absorption by the small intestine. It also stimulates the absorption of various nutrients (calcium, iron, magnesium, etc.).
Olive oil, therefore, is a fat that is digested and absorbed really well. It has choice properties and a mild laxative effect that helps to combat constipation and bad breath.
Obesity and olive oil:
Obesity is a major health issue in the West because people eat large amounts and get little physical exercise. Nowadays, in cities especially, people are adopting a sedentary, stressful life. Over half the population of some industrialised countries is overweight, leading to increased risk of high blood pressure, diabetes, high cholesterol and triglycerides, all factors that increase the risk of cardiovascular diseases.
Obesity or overweight is when energy reserves, primarily in the form of fat, are excessive. It occurs when the amount of energy obtained through the diet is greater than the amount of energy expended. It is corrected by ensuring that energy expenditure (physical exercise, basal metabolic rate, etc.) is greater than energy intake.
Olive oil is a nutrient of great biological value. Like all other fats and oils it is high in calories (9 Kcal per gram), which could make one think that it would contribute to obesity. However, experience shows that there is less obesity amongst the Mediterranean peoples, who consume the most olive oil.
It has been demonstrated that an olive-oil-rich diet leads to greater and longer-lasting weight loss than a low-fat diet. It is accepted better because it tastes good and it is a stimulus to eat vegetables.
Olive oil is a very healthy nutrient that has a high calorie value, which might lead to the belief that its consumption encourages obesity. Experience shows, however, that people who consume most olive oil, suffer less from obesity.
Olive oil and the immune system:
It has also been demonstrated that olive oil plays an importantrole in the immune system.
It has been documented that olive oil intake bolsters the immune system against external attacks from microorganisms, bacteria or viruses.
It has been known for some time that mineral and vitamin deficiencies can have an adverse effect on the immune system.
Recent research has concluded that the fatty acids in the make-up of olive oil are good allies in lowering important immunological parameters such as the proliferation of lymphocytes induced by specific mitogens of both B- and T-cells.
These fatty acids have been reported to play an important part in various immune functions. They are involved in regulating inflammatory processes and they may be effective in the treatment of some autoimmune diseases and in the regulation of the immune system in general.
Olive oil and rheumatoid arthritis:
Rheumatoid arthritis is a chronic inflammatory immune disease of unknown causes that affects the joints. Genes, infective factors, hormones and diet have been suggested as possible associates in its onset. Although some studies had suggested that olive oil could help to alleviate its symptoms they did not provide confirmation of such a protective effect.
Now, the results of a recently published study suggest that regular consumption of olive oil may reduce the risk of developing rheumatoid arthritis.
According to the authors of the study, the people on diets containing high levels of olive oil had less risk of suffering this disease. The study found that the people who consumed less olive oil had 2.5 times more possibility of developing rheumatoid arthritis than those who consumed it more frequently.
Although the mechanism involved is not yet clear, antioxidants are suspected to exert a beneficial effect.
Olive oil during pregnancy and childhood:
Olive oil plays a key role in foetal development during pregnancy and a shortage may have pernicious effects on the baby's subsequent development.
It has been demonstrated that the post-natal development of babies of mothers who consumed olive oil when pregnant is better in terms of height, weight, behaviour and psychomotor reflexes.
The foetus needs vitamin E to grow. The newborn baby also needs a store of vitamin E to fight against the oxidative stress caused on entering an oxygen atmosphere. Although not very abundant in olive oil, it is present in sufficient quantity thanks to the resistance of olive oil to oxidation.
So, both the amount and the type of food consumed in the diet during pregnancy play a key part in the metabolic adaptations that occur in the mother and in her functional relationship with the foetus.
During labour, the vitamin E in the mother's blood is concentrated in the breast glands and so, during breast feeding, the mother continues to supply vitamin E. It is essential to maintain the levels of this vitamin during breast feeding.
Vitamin E is also recommended for premature and new-born infants with kidney or pancreas failure because of the favourable effect it has on the hepato-biliary system.
But olive oil not only provides enough essential fatty acids for the development of the new-born child; its ratio of linoleic acid to linolenic acid (essential fatty acids) is similar to that of breast milk.
The beneficial effect of oleic acid lasts beyond pregnancy. Besides its documented effectiveness in preventing hypercholesterolaemia and atherosclerosis, which is a process that can begin in childhood, oleic acid also appears to exert a positive influence on growth and bone mineralisation and development during infancy.
During pregnancy and breast feeding it is advisable to consume more fat, primarily monounsaturated fat, while reducing saturated fat and cholesterol as far as possible. General dietary guidelines should be followed and calorie intake should be controlled to avoid excessive weight gain.
Under-three-year-olds have different dietary requirements to children over this age. Forty per cent of the energy they consume comes from fat, whether it be in breast milk or any other kind of milk. It is recommended to maintain this dietary pattern and to ensure that energy and nutritional intake cover the developmental requirements of the child.
Olive oil and skin:
External factors, such as the sun's rays, speed up ageing by generating free radicals. Though cells are equipped with mechanisms that neutralise their action, it is possible to reduce cell damage by using inhibitors that lower the risk. One such natural inhibitor is olive oil, whose lipid profile is very similar to that of human skin.
On top of polyphenols, olive oil has a large proportion of vitamins A, D and K, as well as vitamin E, the main source of protection against the free radicals that produce cell oxidation. This makes it a good aid in specific therapies to treat skin disorders such as acne, psoriasis and seborrheic eczemas.
It has also been suggested that because of its pronounced antioxidant effect, olive oil could play a choice part in the prevention of continuous oxidation, one of the processes that influences the development of certain types of skin cancer. Vitamin E studies have begun, but these kinds of observations take a long time, which means that conclusive data are not yet available. However, the theory is that oleic acid is believed to play a major part in counteracting continuous oxidation