Found among the bloodstream lipids
(fats), and all cells in the human body, cholesterol is a soft and waxy substance that is important to form cell membranes, some hormones, and is needed for other essential bodily functions. High levels of blood cholesterol, known as hypercholesterolemia
, is a major risk factor for coronary heart disease
(the cause of heart attacks). Cholesterol does not dissolve in the blood, and has to be carried to and from cells by lipoproteins
. Although there are many kinds of lipoproteins, two are important to know about: low-density lipoprotein
(LDL), and high-density lipoproteins (HDL).
Low-density lipoprotein (LDL) is the major carrier of cholesterol in the blood. LDL cholesterol is commonly known as "bad cholesterol". Too much LDL will build up with other substances along the artery
walls that feed the heart and brain. They combine to form plaque, which is hard, thick deposits that clog the arteries. This condition is called atherosclerosis
High-density lipoprotein cholesterol carries about one-third to one-fourth of the blood cholesterol in the body. HDL cholesterol is known as "good cholesterol" because many experts believe that HDL cholesterol carries cholesterol back from the arteries, to the liver, where it is passed from the body, and removes excess cholesterol from plaques, slowing their growth.