By James M. Rippe

A lipoprotein is a cross between a lipid, such as cholesterol or triglycerides, and a protein. Because fats and water don’t mix well, lipoprotein serves as the mode of transportation for cholesterol and other lipids through the bloodstream, which is mostly water.

Lipoproteins are sort of like a cruise ship steaming across the Atlantic Ocean. View the ship as the proteins, and all the passengers on board (including the Family Cholesterol) as the lipids. Not a perfect analogy, but you get the point.

Lipoproteins can be separated and measured according to their weight and density. They range from very low density to high density. They also range in size from small to large. Lipoproteins also have many different constituent proteins called apoproteins (apo, for short). But you need not get that deep into biochemistry to understand how two types of lipoprotein function in creating or fighting atherosclerosis.

One particularly dangerous form is called LDL or low-density lipoprotein. LDLis dangerous, because it contains more fat and less protein and easily adheres to artery walls, particularly where they are damaged, and enters into plaque formation. Because LDL cholesterol plays such a major role in forming atherosclerotic plaque, lowering LDL levels in the blood is an important goal in controlling cholesterol.

On the other hand, a beneficial type of lipoprotein called HDL, or high-density lipoprotein, can actually help protect your heart from heart disease. HDL doesn’t adhere to artery walls. Instead, it actually helps carry cholesterol away from artery walls.

This effect is particularly important for the coronary arteries. Research also suggests that HDL is an antioxidant and anti-inflammatory regulator that prevents oxidation of LDL and helps block its plaque-forming properties. Thus, keeping HDL at recommended levels helps control overall cholesterol and its potential negative effects.

When you have a checkup, your doctor may look at the results of your blood tests and say, “Well, you need to work on raising your good cholesterol and lowering your bad cholesterol.” That can be a little confusing until you realize that their names offer you a tip for keeping track of which is which.

You want to keep your high-density lipoproteins (HDLs) high and your low-density lipoproteins (LDLs) low. Repeat: High, high! Low, low! Forgetting this mantra can result in ugly consequences for your arteries.