What is cholesterol, and why do we need to be concerned about it if the level is considered high? If your doctor tells you your cholesterol is 250, for example, what does that mean?
In addition to being manufactured in the body, cholesterol is also found in foods derived from animal sources. Cholesterol serves many important functions in our bodies. It’s an integral part of the cell membrane that surrounds every cell in our bodies, keeping all the structures inside the cell from leaking out. It is a building block of other molecules that our bodies need to function, such as vitamin D, and many hormones. Cholesterol is used to make bile acids, which assist in digestion.
Cholesterol circulates in the blood bound to special proteins called lipoproteins, which are classified according to their density. (Lipos is a Greek word meaning “fat.”) So LDL cholesterol is low-density lipoprotein cholesterol (“bad cholesterol”), and HDL cholesterol is high-density lipoprotein (“good cholesterol”). VLDL cholesterol, made up mostly of triglycerides, is very-lowdensity lipoprotein that, when elevated, increases the risk of ASCVD. Taken together, these lipoproteins are referred to as blood fats or blood lipids.
Although cholesterol is absolutely essential for life, high levels of certain lipoproteins (and low levels of HDL cholesterol) can be harmful because they increase the risk of developing plaque in the arteries, the blood vessels through which oxygenated blood reaches all the body’s cells. Atherosclerosis, the name for this process, underlies most heart attacks and strokes.
Our lipoprotein levels are determined both by our genes and by our lifestyles. For example, people who consume diets that are high in starchy carbohydrates will often have high triglyceride levels. Those who eat large amounts of animal fat (found in meat and dairy products such as milk, butter, and yogurt) will often have high levels of LDL cholesterol. There are some people with a rare familial form of high cholesterol who have very high levels of LDL cholesterol even if they are strict vegetarians.