Cholesterol is a steroid alcohol that is usually found in animal cells and body fluid such as blood, milk, egg yolk, and fats and oils. Most of the cholesterol in our body is synthesized in the liver. It is a precursor to most to most steroids and hormones which include: glucocorticoids (example, cortisol- used in treatment of arthritis and other inflammatory conditions), mineralocorticoids (example, aldosterone- help in absorption of bicarbonate, sodium and chlorine ion), androgen (example, testosterone, responsible for the male character), estrogen (estrone and estradiol- regulates the menstrual cycle), progesterone (responsible for maintenance of pregnancy and also prevent ovulation during pregnancy). Cholesterol is also a precursor to bile acids (examples, cholic and chenodeoxycholic acids which help in the digestion of fats and oil), and it is also very important in the development of the structure of organs in the body. A deficiency of it in the developing foetus can result to congenital eye abnormality.
Since it is insoluble, cholesterol is not transported freely in the blood, so they combine with certain proteins called lipoproteins- which include low-density lipoproteins (LDL) and high-density lipoproteins (HDL).
LDL transports cholesterol from the liver to the cells of other tissues which possess LDL receptors. When the LDL receptors are used up due to abundant cholesterol transport, the synthesis is blocked and resumes when the cell is deficient of cholesterol. LDL molecules begin to appear in the blood when the process becomes unregulated which is caused by cells without receptors as a result of certain risk factors such as old age, lack of exercise, overconsumption of fatty foods, family history, smoking, diabetes or high blood pressure. These LDL molecules in the blood are taken up oxidized by microphages and forms foam cells. These foam cells become trapped in the walls of the blood vessels and cause blockages, leading to plaques such as arteriosclerosis (hardening of the blood vessels), heart attacks, strokes and many serious medical problems.
HDL transports excess, unused cholesterol back to the liver in order to be excreted, degraded into bile acids or to be used by tissues that synthesize hormones in reverse cholesterol transport (RCT) process.
There are about 70 to 80 percent LDL cholesterol and 20 to 30 percent HDL cholesterol in the human liver. HDL, when high, correlates better health and are termed good cholesterol while LDL are termed bad cholesterol.
The distribution of cholesterol is vital in the body as mentioned above, as our body tissues and cells cannot do without cholesterol (our body’s normal cholesterol level is between 150 to 200mg/dl). However, it is more important that there is balance in the amount of cholesterol needed by our body; that is, balance between the cholesterol we take in and that that goes out of our body, as an imbalance results in atherosclerosis (the deposition of fatty materials on the inner walls of the arteries), heart diseases, strokes and other heart-related illnesses. In that case, eating foods less in fats and oil, less sugar, regular exercises, avoidance of smoking, and maintaining healthy habits, will go a long way in regulating the balance of cholesterol in our body, and thus prevent heart diseases and other problems associated with it.