In the 6th century BC, Solon, the great Athenian legislator, drafted the first law for the protection of the olive tree excluding the uncontrolled felling. The olive tree was a symbol in ancient Greece and the olive oil was used not only for its valuable nutritional quality but also for medical purposes. The health and therapeutic benefits of olive oil were first mentioned by Hippocrates, the father of medicine, who used olive oil to treat his patients, as it is reported in ancient and modern medical texts. Hippocrates called olive oil "the great healer" and used it to cure hundreds of illnesses. Modern scientific research studies conducted by prominent European and American Universities, confirmed Hippocrates's beliefs and proved many of the therapeutic and nutritional attributes of olive oil, and the important role that it plays in our health when consumed as part of a balanced diet.
Olive Oil and Cardiovascular Diseases
Cardiovascular diseases are the top cause of death in the industrialized 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.
"… The lowest rates of death from coronary heart disease are currently recorded in the countries where olive oil is virtually the only fat consumed" states Professor Francisco Grande Covián.
Olive Oil and Arteriosclerosis
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
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.
Olive Oil and Cancer
Epidemiological studies suggest that olive oil exerts a protective effect against certain malignant tumors (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 a 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 the beneficial effects of olive oil on pre-cancerous lesions. After analyzing three types of diet, research scientists arrived at various conclusions. The olive oil diet reduced the number of cancerous lesions; the number of tumors that developed was clearly and significantly low, and the tumors 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 tumors.
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 favorable 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 centered on the protection provided by olive oil against child leukemia 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 inhibition of the growth of different types of cancer. However, according to the information available at present, olive oil could act simultaneously during the different stages involved in the process of cancer formation.
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 fiber 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 and Obesity
Olive oil is a nutrient of great biological value. Like all other fats and oils, it is high in calories (8.5 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 population, 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 and 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 affect 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 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 esophagus. Because of this, it reduces the risk of the flow or reflux of food and gastric juice up from the stomach to the esophagus. 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 favoring 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 gallbladder. Another effect is that it is cholecystokinetic, i.e. it stimulates the contraction of the gallbladder, 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 gallbladder, 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 the 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.
Olive Oil and Osteoporosis
Olive oil appears to have a favorable effect on bone calcification, and bone mineralization 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 Function
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 number 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 aging. 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 during Pregnancy and Childhood
Olive oil plays a key role in fetal 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, behavior and psychomotor reflexes. The fetus needs vitamin E to grow. The newborn baby also needs a store of vitamin E to fight against the oxidative stress caused by 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 fetus.
Olive Oil and Breastfeeding
During labor, the vitamin E in the mother's blood is concentrated in the breast glands and so, during breastfeeding, the mother continues to supply vitamin E. It is essential to maintain the levels of this vitamin during breastfeeding. Vitamin E is also recommended for premature and new-born infants with kidney or pancreas failure because of the favorable 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 hypercholesterolemia and atherosclerosis, which is a process that can begin in childhood, oleic acid also appears to exert a positive influence on growth and bone mineralization and development during infancy.
During pregnancy and breastfeeding 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 for children over this age. Forty percent 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.