A small amount of cholesterol circulates in the blood in complex particles called lipoproteins. Each particle contains a combination of protein, cholesterol, triglyceride, and phospholipid molecules and the particles are classified by their density into high-density lipoproteins (HDL), low-density lipoproteins (LDL), and very low-density lipoproteins (VLDL). HDL-C particles, sometimes called "good" cholesterol, carry excess cholesterol away for disposal and LDL-C particles, or "bad" cholesterol, deposit cholesterol in tissues and organs.
Monitoring and maintaining healthy levels of cholesterol is important for staying healthy. The body produces the cholesterol needed to work properly, but the source for some cholesterol is diet. If an individual has an inherited predisposition for high cholesterol levels or eats too much of the foods that are high in saturated fats and trans unsaturated fats (trans fats), then the level of cholesterol in that person's blood may increase and have a negative impact on the person's health. The extra cholesterol in the blood may be deposited in plaques on the walls of blood vessels. Plaques can narrow or eventually block the opening of blood vessels, leading to hardening of the arteries (atherosclerosis) and increased risk of numerous health problems, including heart disease and stroke.