Cholesterol

Cholesterol, a naturally occurring substance produced by the liver within the body, is essential for the maintenance of healthy cells and the synthesis of bile and steroid hormones. Too much cholesterol in the circulation however, is a major risk factor for the development of cardiovascular disease (CVD), currently the most significant cause of mortality in Ireland.

Blood cholesterol levels are typically reported as total cholesterol, high density lipoprotein (HDL) cholesterol, and low density lipoprotein (LDL) cholesterol in units of mmol/l. However, the terms LDL cholesterol and HDL cholesterol are actually something of a misnomer. More accurately they are particles of fat and protein which transport cholesterol around the body, as opposed to being cholesterol themselves. LDLs facilitate the movement of cholesterol to tissues of the body and, due to their high fat and low protein composition (hence, low-density), are implicated in the development of arterial plaques, or atheromas, a build up of rigid material on the internal wall of an artery. Such plaques can restrict, or even block blood flow entirely to major organs such as the heart and brain, thus contributing to heart attack or stroke events. Conversely, HDLs, with their low proportion of fat to protein (thus, high-density) have protective effects, transporting cholesterol away from tissues and back to the liver where it can be re-used or broken down for excretion. For these reasons, high levels of LDL may increase your risk of developing CVD, even if your total cholesterol is low, while high levels of HDL may decrease your risk, regardless of total cholesterol levels.