Cholesterol: The Good, The Bad, and The Essential

Over the years, you’ve heard about how cholesterol can negatively affect your health. But cholesterol actually also plays an essential role in staying healthy—it is an essential building block for cells. Different types of cholesterol—low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides—play their own role in the body.

This animated sequence shows the first step in how LDL molecules work to improve the functioning of your body’s cells. The LDL molecules bind to receptors on a cell’s surface, resulting in a vesicle (bubble of liquid) that then brings the LDL into the cell. 

The animation to the left starts inside of a cell in your body. In it, you can see the LDL molecules being transported to what’s called the “endoplasmic reticulum.” There, the LDL molecules are broken down into smaller pieces, then transported by vesicles to the cell’s surface, where they will be used to help build the cell wall.

Cholesterol is a building block for healthy tissue and membranes. It enables cells to adapt to temperature changes; maintains membranes within the nervous system, brain, spinal cord, and peripheral nerves; and protects the myelin sheath that insulates nerves from surrounding tissue. 

The structure of HDL and LDL differs significantly. Smaller HDLs contain a higher concentration of protein molecules. A shell of phospholipids and unesterfied cholesterol surrounds larger LDLs. The difference in coatings means that these two types of molecules travel to different places in the body and do different things. Because blood has a watery composition and cholesterol is fatty, the two don’t mix well. High levels of LDL tend to accumulate in the blood vessels and cause damage.

By moving the slider to the left, you’ll be able to see the difference in the phospholipid coating that encapsulates LDL and HDL particles.

Cholesterol is important to the proper growth of cell walls because cholesterol molecules contain large amounts of phospholipids—the same material that makes up cell membranes. What cholesterol essentially does in the body is replenish the body’s cells’ phospholipids.

In the animation to the left, we can see how the pieces of the original LDL molecule (“free cholesterol”), held in a vesicle, float back to the surface of the cell and rejoin the cell membrane. The merging of cholesterol with the membrane strengthens the cell walls, keeping them healthy and functioning properly.

HDLs and LDLs are part of a complex biochemical process that takes place constantly inside the body. When you eat something, the microvilli of the small intestine digest the food particles and transport them through the lymphatic system to the bloodstream. After the food is partially digested, particles of fat enter cells lining the first section of the small intestine, where they are repackaged as fat—a lipid inside a protein or “lipoprotein”—so that they can travel through the bloodstream to the liver, where they will be converted to usable cholesterol. This animated sequence shows this process in action.

Lipoproteins travel through your entire body, eventually reaching your liver. Once in the liver, these particles are processed into other forms of lipoprotein that your body can use, including HDL and LDL cholesterol. Your liver produces more than three-quarters of the cholesterol in your body. The remaining amount comes from the food you eat. Red meat, poultry, fish, seafood and dairy products are the primary sources of dietary cholesterol. Typically, for about 8 hours after a meal, your liver breaks down dietary cholesterol and triglycerides from the bloodstream.

Blood cholesterol level is expressed in milligrams per deciliter (mg/dL). Healthcare professionals consider an HDL level above 40 in males and 50 in females and an LDL level below 100 as desirable. Total cholesterol should be less than 200 and triglycerides should be less than 150.

Move the slider from left to right to see how an increase in LDL (“bad”) cholesterol can lead to a buildup and clogging of the arteries, significantly raising the risk of heart disease. 

On the other hand, it is important to keep your HDL levels up. By moving the slider from left to right, you can see how an increase in HDL simultaneously lowers LDL levels—thereby lowering the overall amount of artery-clogging cholesterol in your bloodstream. HDL cholesterol protects against heart attacks and lowers your risk of heart disease.

The best way to manage cholesterol is to establish a healthy diet, exercise regularly, and avoid smoking. Niacin and other substances—including Omega-3 fatty acids, green tea extract, and certain foods—can have a positive effect on both HDL and LDL cholesterol levels.

Now that you know what cholesterol does in your body, the next step is going back to your charts (or your doctor) and looking at your own numbers. Figure out where you stand—where you are doing well, and where you can improve.

Then take the next step: make a concentrated effort to eat better, exercise more, and stay motivated to lower your cholesterol. By doing so, you'll add years to your life.