What is Cholesterol?

By: Liz Harmon


LDL (low-density lipoprotein) is considered the "bad" cholesterol because it leaves cholesterol in the blood vessels. LDL can contribute to the build up of plaque which is a hard, thick deposit that can clog arteries. HDL (high-density lipoprotein) is considered the "good" cholesterol because it removes harmful cholesterol from the blood stream. HDL scavenges through the blood stream to find the LDL and carry it out of the blood stream.

How are they Difference?

LDL is made up of 50% cholesterol and 25% protein while HDL is made up of only 20% cholesterol and 50% protein. Since LDL has less protein in the particle it is less dense while HDL has more protein in the particles making it more dense. LDL is made up of a different protein than HDL. LDL is made up of a protein called B-100 while HDL is made up of a protein called A-I and A-II. This is important because they type of protein determines the function of the lipoprotein particle.

The main difference between the two functions is the particles deliver cholesterol to different parts of the body. LDL brings cholesterol to the cells which can cause buildups in the arteries. Buildups can lead to blockages in the arteries which can also lead to heart disease or even stroke.

At the Doctors

Doctors monitor HDL and LDL factors because a person's levels can help a doctor to evaluate a person's health. The doctor can also use the levels to determine if a person is at risk for heart disease. Doctors use the information to know whether more cholesterol is being carried to or from the cells.

Doctors also monitor triglycerides in the blood along with cholesterol levels. Triglycerides are another fat in the blood stream that is used to store energy and give energy to the muscles. Too much can increase the chances of having heart disease.

What the Cholesterol Test Means and How it is Related to Heart Disease

For the total cholesterol levels (HDL and LDL), someone with 240 mg/dL and above is at a high risk for heart disease. Anyone at 200-239 mg/dL is borderline, and anyone less than 200 mg/dL is in the desirable range and is not at risk for heart disease. For total LDL, 190 mg/dL and above mean that you are at a high risk for heart disease. This indicates that an individual should start intensive treatment which can include life style changes, diets and exercise. For total HDL, less than 40 mg/dL means that there is a high risk of heart disease. There needs to be more HDL in the blood stream to carry out the LDL cholesterol.

LDL can build up in the walls of your arteries which makes the arteries narrowed and blood flow is blocked or stopped to the heart. Blood carries oxygen to the heart, so when blood supply is cut off, it can lead to heart problems. Too little HDL means that there is more LDL in the blood stream, so there is a higher chance of heart disease. There needs to be more HDL than LDL in the blood stream to stay healthy.

Healthy Lifestyles

To change HDL and LDL levels, maintaining a healthy diet and regular physical activity can change LDL and HDL levels. A healthy diet will reduce fat and cholesterol will increase HDL levels and decrease LDL levels. Healthy food choices include oatmeal, beans, strawberries, nuts, apples, etc. Too much saturated and trans fats can cause LDL level to increase. Saturated fats include any animal products including butter, milk, beef, poultry and more. Lowering the amount of saturated fats you eat can lower your cholesterol levels. Unsaturated fats can help improve blood cholesterol levels when used in place of saturated and trans fats. Unsaturated fats include fish, salmon and trout, avocados, olives, walnuts and liquid vegetable oils. Trans fats are found in fried foods and pastries including french fries, cheeseburgers, cookies and more. Trans fats raise your LDL levels and lower your HDL levels increasing risk for heart disease.


American Heart Association. (2016). Good vs. Bad Cholesterol. Retrieved March 10, 2016, from http://www.heart.org/HEARTORG/Conditions/Cholesterol/AboutCholesterol/Good-vs-Bad-Cholesterol_UCM_305561_Article.jsp#.VuG4CPkrLIU

Kamps, A. (n.d.). How Do LDL and HDL Differ Structurally and Functionally? Retrieved March 11, 2016, from http://healthyeating.sfgate.com/ldl-hdl-differ-structurally-functionally-2003.htm

American Heart Association. "Know Your Fats." Know Your Fats. N.p., 2016. Web. 13 Mar. 2016. <http://www.heart.org/HEARTORG/Conditions/Cholesterol/PreventionTreatmentofHighCholesterol/Know-Your-Fats_UCM_305628_Article.jsp#.VuWOMPkrKM8>.