The number one reason why the olive oil is healthy is that the molecules making up the oil are both in a fluidity friendly to vascular health and in a durability that will not be broken down by oxygen immediately. Because most of the fat molecules of olive oil, in other words, triglycerides, are composed of monounsaturated fatty acids.
Fatty acids have two main functions in the body. First is that they are used by the body as building materials. For example, our cell walls are woven with slightly modified fatty acids. The second is that they are burned as a source of energy. Another important benefit of high-quality olive oil comes from the antioxidants it contains. Just like other fresh fruits, olive oil is a rich source of antioxidants when it is fresh.
Antioxidant molecules of which function is to resist against oxidation, as befits the name, are called as polyphenols because they structurally contain phenol rings. I recommend you to read a more detailed article about polyphenols in plants from the Magazine Sarkac. Even if it is vegetable, no other oil obtained by refining has the characteristics of fresh fruit. Containing Vitamin E also, olive oil has fat-soluble molecules very similar to oleuropein, an antioxidant unique to olives. The European Food Authority (EFSA) names all these as hydroxytyrosol derivatives. It is accepted by the relevant commission decision of EFSA and the European Union that if 20 mg of quality olive oil has more than 5 mg hydroxytyrosol which has maintained its fruit freshness while being processed, and if the consumer consumes at least 5mg of these substances per day, it prevents the oxidation of bad cholesterol in the veins. Namely, an olive oil which meets these conditions is officially “beneficial to health”. (2012 EU No 432/2012 commission decision)
A triglyceride made up of three fatty acids and a glycerol, are molecules that make up more than 98% of the structure. The fatty acid at the top is saturated palmitic acid, the middle is monounsaturated oleic acid, and the bottom is polyunsaturated linoleic acid. Visual Source: https://sarkac.org/2017/07/zeytinyagi-neden-saglikli-zeynep-delen-nircan/
There are some controversies in the statement of this official decision and the standardization of measurement methods; however, it can be said that consuming 20 g or 2 tablespoons of extra virgin olive oil containing at least 250 ppm (i.e. 250 mg per kilogram and above) polyphenols per day will provide maximum health benefits. Therefore, conscious producers and consumers pay attention to the polyphenol content of the products as a quality indicator.