Cholesterol is a natural lipophilic alcohol contained in the cell membranes of all living organisms. Cholesterol is insoluble in water, soluble in fats and organic solvents. Nearly 80% of cholesterol is produced by the organism (liver, intestines, kidneys, adrenals, gonads), the remaining 20% comes with food. Approximately 80% of free cholesterol and 20% of bound cholesterol are found in the organism. Cholesterol provides stability of cellular membranes, is important for synthesis of vitamin D, production of steroid hormones, including cortisol, cortisone, aldosterone, female sex hormones estrogen and progesterone, male sex hormone testosterone. Also according to recent data it plays an important role in the brain synapses and the immune system, including protection against cancer.
Cholesterol acts as a modifier of the cellular wall bilayer, giving it a certain stiffness by increasing the density of packing the molecules of phospholipids. Cholesterol is stabilizer of plasma membrane fluidity.
As cholesterol is poorly soluble in water and therefore it can not be delivered to tissues in the free form. That is why in the blood cholesterol exists in the form of soluble complex compounds with specific protein transporters called apolipoprotein. Such complexes are called lipoproteins.
There are several types of apolipoproteins with different molecular weight, degree of affinity to cholesterol and degree of solubility of the complex compound with cholesterol (a tendency to precipitation of cholesterol crystals and the formation of atherosclerotic plaques).
There are the following cholesterol types :
Studies have established the relationship between the amount of various type of lipoproteins and human health. High blood levels of LDL is related atherosclerotic disorders in the body. For this reason this type of cholesterol is called bad. Low density lipoproteins are poorly soluble and tend to release in the sediment of cholesterol crystals and the formation of atherosclerotic plaques in blood vessels, thereby increasing the risk of heart attack or stroke and other cardiovascular complications.
Elevated levels of bad cholesterol can also be observed in some liver and kidney diseases accompanied by disorders of high density lipoprotein biosynthesis. High LDL levels can have a hereditary origin. This condition is known as family dyslipoproteinemia.
Factors that can lower the amount of low density lipoproteins include:
In certain cases herbal and synthetic cholesterol medications are required.