In 1954, revolutionary scientific studies (Keys, Anderson, Grande) published a comparison of the number of cardiovascular deaths in the Mediterranean compared to the rest of Europe, with an emphasis on food intake, especially fats, across countries. As a result of these studies, the hypothesis that the significantly lower mortality from cardiovascular disease in the Mediterranean is related primarily to a substantially different fat composition in the Mediterranean diet. In connection with this hypothesis, the term "Mediterranean diet", which is characterized by a high content of cereals, vegetables, pulses and fruits, fish with olive oil as the main source of fats, began to be used. Since then, several studies have emerged to deepen the concept of the Mediterranean diet and its beneficial effect on the human body.
OLIVE OIL COMPOSITION
97% of the oil is triglycerides and free fatty acids (acidity). Of these, 60-83% are monounsaturated fatty acids (oleic acid), 5-22% polyunsaturated and 13-20% saturated fatty acids. Olive oil is recognised as the richest natural source of monounsaturated acids.
The remaining 3% consists of a wide range of substances responsible for antioxidant and organoleptic, especially aromatic, oils. These include, inter alia, vitamin E, the need for which is routinely consumed by olive oil, polyphenols and beta carotenes, all of which have a very strong antioxidant capacity (polyphenols are also anti-inflammatory). It is important to note that during the refining process, which makes virgin oil non-virgin, most of the substances responsible not only for aroma and taste but also for its antioxidant effects are degraded.
Therefore the key benefits of consuming olive oil are limited to virgin oil types as the only beneficial substance still found in non-virgin oils after refinement is oleic acid. The ratio of antioxidants to total oil volume also decreases depending on the ripeness of the olives.
The recommended fat intake should not exceed 35%. An adult should have an energy supply of approx. 2500 Kcal, of which fats 875 Kcal. Of which 15-20% monounsaturated fats. ie about 55g (4-5 tablespoons) of olive oil per day.
Diet is one of the factors influencing the hardening of arteries. A high proportion of monounsaturated fatty acids contribute to lowering the level of "bad" LDL cholesterol, reducing arterial hypertension, while increasing the level of "good" cholesterol HDL in blood plasma and reducing the risk of thrombosis.
The risk factors for high blood pressure include excessive intake of sodium, alcohol, saturated fats and lack of calcium. However, by increasing the intake of polyunsaturated acids, which are contained in olive oil and to a lesser extent, in animal fats, contributes to reducing the risk. The Meditteranean diet also combines this with frequent consumption of fish from the blue fish group (which includes tuna, mackerel and sardines) which are also rich in polyunsaturated fats.
DIGESTIVE TRACT DISEASES
Olive oil has a positive effect on gastric, pancreatic and bile secretion due to the stimulatory effect of oleic acid in the breakdown of fats. Epidemiological studies have also shown that instances of gallstones are lower in countries with higher olive oil consumption. Studies have also shown that a regular diet with a predominant amount of monounsaturated fats can reduce stomach acidity. And finally, the anti-inflammatory effect of virgin olive oil in connection with gastrointestinal disorders has been reported in scientific studies of patients suffering from inflammatory bowel disease.
Epidemiological studies have shown that the Mediterranean diet reduces the risk of type 2 diabetes and reduces the risk of secondary complications in patients suffering from the disease. Obesity is a risk factor for diabetes, which, based on statistical data, is most often related to excessive intake of saturated fats. It is recommended to maximise the proportion of monounsaturated fatty acids as the total proportion of fat in the diet and olive oil is the richest natural source of this beneficial fatty acid.
OXIDATIVE STRESS AND FREE RADICALS
Free radicals are atoms or groups of atoms with an unpaired number of electrons. They arise naturally within normal metabolic processes but can also be produced by external sources such as radiation, smoking, chemicals, air pollution, etc. Free radicals are highly reactive due to electron imbalance and, if not regulated by antioxidants they can damage lipids, proteins and DNA and cause a variety of diseases.
Oxidative stress arises from an imbalance between free radicals and antioxidants in the body. Low content of antioxidants does not allow the regulation of free radicals and therefore does not prevent their negative effect on the human body. Oxidative stress is linked to serious diseases such as Parkinson's disease, heart failure, heart attack, Alzheimer's disease, chronic fatigue syndrome, etc.
Antioxidants are molecules that are stable enough to pass on the free radical the missing electron and thus neutralize it. Some antioxidants are metabolic products, others are ingested in the diet. Unlike refined oils, virgin olive oil is a rich source of strong antioxidants. Among the most important antioxidants taken in olive oil are vitamins E, C, polyphenols and beta carotene.
The positive effect of olive oil in reducing the risk of cancer is still less well-known than the effects on other diseases. Studies in this area focus mainly on the low incidence of breast cancer in Spain, which is about 40% lower than in the US and northern European countries. This is mainly attributed to the composition of fats in the Mediterranean diet. Similar results are shown when comparing instances of ovarian cancer, and again, these suggest the influence of the Mediterranean diet in reducing the risk without detailing a specific mechanism.
In a large-scale study conducted in 7 European countries involving 13,000 people correlating diet and cardiovascular disease, a correlation was identified between long-term increased monounsaturated fatty acid intake and life expectancy.