LDL Cholesterol

Cholesterol is a chemical that is considered to be a lipid (a compound dissolvable in organic solvents but not in water) and a sterol (combination steroid and alcohol) which is vital in the construction and maintenance of cell membranes.

Triglycerides are compounds which consist of three fatty acids joined together into one big molecule. They are an important cellular energy source and the origin of most of the fat in the human body.

Because neither of cholesterol or triglycerides are soluble in blood (which is mostly made up of water), organisms need a way of getting them to become soluble in water so they can be transported from the liver (which metabolizes proteins, carbohydrates and fats, turning them into substances that are used to sustain life) as needed throughout the body.

Enter the Lipoproteins

Low-density lipoproteins (known popularly as LDL cholesterol or LDLs) are packets which basically consist of an apolipoprotein molecule which encircles its cargo of fatty acids, thus, enabling them to travel in aqueous solution. Its structure consists of a hydrophobic core of linoleate and cholesterol and a shell made up of phospholipids, the B-100 apolipoprotein molecule, and more cholesterol. They are derived from precursors known as VLDLs, which turn into LDLs after they have lost a portion of their triglyceride load.

Phew... now with the scientific explanation out of the way. :-) The diagram below can give a good bird's eye view of the manner in which LDLs are stored in the arteries.

Why the focus on LDL?

LDL is a major focus of health programs, doctors, nutritionists, epidemiologists, and other experts today because it has been implicated in the promotion of heart disease, a leading cause of death in today's relatively sedentary society. More specifically, excessive levels of LDL and low levels of HDL contribute to atherosclerosis, or the formation of atheromas, fatty deposits in the walls of arteries. Over time, these deposits can build up, constricting the arterial passage and leading to reduced blood flow and such conditions as heart failure, peripheral vascular disease, and ischemic events such as heart attacks and strokes.

LDL is colloquially known also as 'bad cholesterol,' for its association with heart disease, even though the cholesterol it carries is no different than that carried by high-density lipoproteins (HDLs).

What LDL Levels Should I Have?

Health organizations such as the National Institute of Health and the American Heart Association recommend a fasting level of LDL cholesterol of less than 100 mg/dL. This represents the optimal amount for a reduced risk of developing heart disease. Their guidelines also state that an LDL level greater than 190 mg/dL poses the greatest risk to a person of developing heart disease. For people who are already at increased risk, they recommend an even more drastic reduction of LDL levels, based on mortality rates of people who have taken cholesterol-reducing drugs such as statins.