Cholesterol is a fat-like substance produced mostly in the liver and important in the structure of cells throughout the body as well as the manufacture of various hormones. Cholesterol is a major constituent of the waxy atherosclerotic deposits that gradually can clog up the inside of the arteries, usually raising the blood pressure (hypertension). When these deposit develop in crucial arteries, such as the coronary vessels of the heart, they can lead to heart attacks and strokes.
Cholesterol is a very important part of the body and to good health. It is a structural molecule that is an essential part of every single cell membrane. It is used to make steroid hormones such as testosterone, oestrogen and cortisol; helps metabolism work efficiently; and produces bile acids, which helps the body digest fat and absorb important nutrients.
Cholesterol in the blood comes in two forms: "high density lipoprotein" (HDL) and "low density liporotein" (LDL) and the balance of the two in the body may be as important as the amount. LDL is further narrowed down to two subtypes: dense, small particles and large, fluffy particles. The dense small-particle LDL type has been identified as a risk factor for increasing heart disease risk, while large LDL particles constitute a lower risk.
There are two ways cholesterol gets to the blood stream. The liver produces cholesterol and adjusts the blood cholesterol level according to essential needs for cholesterol. A diet high in saturated fats can lead to elevated levels of low-density lipoprotein (LDL or "bad") cholesterol and reduced levels of high-density lipoprotein (HDL or "good") cholesterol. However, despite being vilified for decades, dietary cholesterol is understood to be far less detrimental to health than scientists once thought. The effect of cholesterol in food on the level of cholesterol in our blood is actually quite small.
In 1994 it was reported that the link between cholesterol and heart disease is at least twice as strong as previously thought. The new studies say that a 10% fall in cholesterol translates into a cut in the death risk of 50% by age 40, by 40% by 50, and by 30% at age 60. Although there is little benefit seen in the first two years, the reduction in risk is apparent after 5 years. A Scottish study from 1995 showed that lowering one's cholesterol by 20% with a drug reduced the risk of heart attack by 28% even in those who had no previous known heart trouble.