Olive oil and health

CHOLESTEROL
An important action of olive oil is the prevention of cardiovascular diseases. 
In fact, there are two types of cholesterol in our body: HDL (the "good cholesterol" a real cleaner of arteries, which removes cholesterol form artery walls and brings it back to the liver, where it contributes to bile formation, whose function, in digestion, is to emulsify fat) at high lipoprotein density, and LDL (the "bad cholesterol") at low intensity.
Polyunsaturated fatty acids reduce both LDL and HDL cholesterol. They are highly unstable, quickly oxidise, and form dangerous free radicals for human body. Monounsaturated fatty acids, which are abundant in olive oil, reduce the LDL but not HDL, and better resist oxidation.
A diet including high olive oil content helps keeping LDL levels low, while it does not reduce HDL, which is protected by high content of monounsaturated fatty acids in olive oil. This is a way for prevention against cardiovascular diseases, arteriosclerosis, myocardial infarction, avoiding the accumulation of fat in artery walls.

VITAMINS
Olive oil is very important for our body, also because it contains many vitamins: A and D, and E in particular. Vitamin E, if it is in a good ratio with linoleic acid and polyunsaturated acid, helps reducing the risk of thrombosis, and contrasts fat oxidation (avoiding the formation of endoperoxides); in the human body, it also fights against the formation of free radicals and aging processes. The best effects are obtained with the Vitamin E/linoleic acid ratios >0.79: it is 1.87 for olive oil, and approximately 0.5 for seed oils.

OTHER PROPERTIES
Olive oil facilitates bile secretion to the intestine, lubricates the intestinal walls, has a laxative action, and protects gastric mucous membrane. 
It contains linoleic and linolenic acid, essential acids (that the human body cannot synthesise) prostaglandin precursors (with anti-inflammatory, vasostimulating, and immune action), which carry fat-soluble vitamins, with plastic activities for cells and platelet aggregation regulators, and for synthesis of hormone substances. Olive oil also contains phospholipids, which are necessary for fat digestion, and antioxidant substances acting against free radicals, which cause cellular degenerations. Olive oil also has tonic, anti-anaemic, emollient, energetic, and hypoglycaemic properties.