High cholesterol is the best known of all the many threats to a healthy heart. When excess amounts of this waxy, fat-like substance build up along the walls of the arteries, you face a dramatically higher risk of a complete blockage, leading to a heart attack or stroke. At normal levels, cholesterol is not a bad thing. On the contrary, it's an essential raw material used by the body to build cell walls and produce hormones such as estrogen and testosterone. The body produces its own supply of cholesterol in the liver, and it's found naturally in all animal products (such as meats, eggs, milk, and cheese). It poses a problem only when the body is unable to use or eliminate excessive supplies. You are generally considered at risk of heart disease if two or more of the following factors apply to you: * Cigarette smoking * High blood pressure * Low HDL cholesterol (below 40) * A family history of early heart disease (before 55 in a man, or 65 in a woman) * Your own age (over 45 if you're man, over 55 if you're a woman)
Cholesterol is a sterol (a combination steroid and alcohol) and a lipid found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. Lesser amounts of cholesterol are also found in plant membranes. The name originates from the Greek chole- (bile) and stereos (solid), and the chemical suffix -ol for an alcohol, as researchers first identified cholesterol in solid form in gallstones in 1784. Most cholesterol is not dietary in origin; it is synthesized internally. Cholesterol is present in higher concentrations in tissues which either produce more or have more densely-packed membranes, for example, the liver, spinal cord and brain, and also in atheromata. Cholesterol plays a central role in many biochemical processes, but is best known for the association of cardiovascular disease with various lipoprotein cholesterol transport patterns and high levels of cholesterol in the blood. When doctors talk to their patients about the health concerns of cholesterol, they are often referring to "bad cholesterol", or low-density lipoprotein (LDL). "Good cholesterol" is high-density lipoprotein (HDL); this denotes the way cholesterol is bound in lipoproteins, the natural carrier molecules of the body.
