What is Cholesterol?

Maulik Sarin

What is LDL?

LDL is a microscopic blob that's made up of an outer rim of lipoprotein that surrounds a cholesterol center. Its full name is "low-density lipoprotein."


LDL Cholesterol: How It Effects Your Heart Disease Risk. (n.d.). Retrieved from http://www.webmd.com/cholesterol-management/ldl-cholesterol-the-bad-cholesterol

What is HDL?

HDL removes harmful bad cholesterol from where it doesn't belong. High HDL levels reduce the risk for heart disease, but low levels increase the risk. HDL is short for high-density lipoprotein. Each bit of HDL cholesterol is a microscopic blob that consists of a rim of lipoprotein surrounding a cholesterol center. The HDL cholesterol particle is dense compared to other types of cholesterol particles, so it's called high-density. HDL cholesterol scavenges and removes LDL. HDL reduces, reuses, and recycles LDL cholesterol by transporting it to the liver where it can be reprocessed. HDL cholesterol acts as a maintenance crew for the inner walls (endothelium) of blood vessels. Damage to the inner walls is the first step in the process of atherosclerosis, which causes heart attacks and strokes. HDL scrubs the wall clean and keeps it healthy.


HDL Cholesterol: "The Good Cholesterol" (n.d.). Retrieved from http://www.webmd.com/cholesterol-management/hdl-cholesterol-the-good-cholesterol

How do LDL and HDL differ structurally?

All types of lipoproteins contain both lipids and proteins, but the relative composition of each lipoprotein varies. The main structural difference between LDL and HDL is their compositions. Approximately 50 percent of the weight of an LDL particle is cholesterol and only 25 percent is protein. High-density lipoprotein particles, on the other hand, consist of 20 percent cholesterol by weight and 50 percent protein. Since protein is more dense than fat, HDL particles are more dense than LDL particles, hence the names "high-density" and "low-density" lipoproteins. The other major structural difference between LDL and HDL relates to the types of protein they contain. Low-density lipoproteins contain proteins called B-100 proteins, while HDL particles contain mostly A-I and A-II proteins. The type of protein is significant because it determines the function of the lipoprotein particle.


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

How do LDL and HDL differ functionally?

Low-density lipoproteins and high-density lipoproteins both transport cholesterol in the blood, but the main functional difference between the two is they deliver cholesterol to different parts of your body. Low-density lipoproteins -- the primary carriers of cholesterol -- bring cholesterol to cells throughout your body and can cause cholesterol to buildup within your arteries. This buildup can eventually lead to arterial blockage and an increased risk for heart disease and stroke. High-density lipoproteins, on the other hand, can benefit your health because these particles carry cholesterol away from your heart and other organs and deliver it back to your liver, where it is passed from your body.


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

Why do doctors monitor the concentrations of LDL and HDL in patients’ blood?

Too much LDL in the bloodstream can result in cholesterol plaques forming inside arteries. This results in atherosclerosis, or hardening of the arteries, and can lead to heart attack and stroke. Low levels of LDL cholesterol are associated with good cardiovascular health and a low risk of heart disease. Since HDL carries cholesterol away from cells and toward the liver, it helps combat the action of LDL. Doctors measure HDL to ensure that levels are high enough to promote good cardiovascular health.


Henrickson, K. (2015, April 23). Why Do Doctors Monitor the Concentration of LDL & HDL? Retrieved from http://www.livestrong.com/article/144497-why-do-doctors-monitor-the-concentration-of-ldl-hdl/

How are the concentrations of LDL and HDL associated with the risk for heart disease and associated disorders?

Low levels of LDL cholesterol are associated with good cardiovascular health and a low risk of heart disease. Doctors measure HDL to ensure that levels are high enough to promote good cardiovascular health.


Henrickson, K. (2015, April 23). Why Do Doctors Monitor the Concentration of LDL & HDL? Retrieved from http://www.livestrong.com/article/144497-why-do-doctors-monitor-the-concentration-of-ldl-hdl/

What other molecules in a patient’s blood are monitored along with LDL and HDL?

Other molecules monitored along with LDL and HDL in a patient's blood include triglycerides, low density lipoproteins, and high density lipoproteins. Triglycerides are a type of fat found in the bloodstream inside of cholesterol molecules, therefore, high levels of triglyceride increase the risk for heart disease.


What Other Molecules in a Patient's Blood Are Monitored Along With LDL and HDL? - What is Cholesterol? (n.d.). Retrieved from https://sites.google.com/site/whatischolesterolhss/what-other-molecules-in-a-patient-s-blood-are-monitored-along-with-ldl-and-hdl

What do the results of a cholesterol test mean? How do patients interpret each value?

Total blood cholesterol level:

High risk: 240 mg/dL and above

Borderline high risk: 200-239 mg/dL

Desirable: Less than 200 mg/dL


LDL cholesterol levels:

190 mg/dL and above represents a high risk for heart disease and is a strong indicator that the individual can benefit from intensive treatment, including life style changes, diet, and statin therapy for reducing that risk.


For LDL levels that are equal to or less than 189 mg/dL, the guidelines recommend strategies for lowering LDL by 30% to 50% depending on what other risk factors you have that can affect the health of your heart and blood vessels.


HDL cholesterol:

High risk: Less than 40 mg/dL


Triglyceride levels:

Very high risk: 500 mg/dL and above

High risk: 200-499 mg/dL

Borderline high risk: 150-199 mg/dL

Normal: Less than 150 mg/dL


Cholesterol Tests: Understand Your Results. (n.d.). Retrieved from http://www.webmd.com/cholesterol-management/cholesterol-tests-understand-your-results?page=2#1

What can patients do to change the levels of LDL and HDL in their blood?

A healthy diet will higher HDL and lower LDL. Saturated fat intake should be limited to 7% or less of total calories. Cholesterol should be 200mg or less per day. Omega 3 fatty acids will increase HDL. Exercise can raise HDL levels by as much as 5%. However, the activity needs to be consistent with at least 30 minutes a day and for at least five days a week. About every 6 pounds lost can raise HDL by one and lower LDL by one. Medications can also be used to increase HDL and/or LDL levels.


What can patients do to change the levels of LDL and HDL in their blood? (n.d.). Retrieved from http://cholesterolinformationforyou.weebly.com/what-can-patients-do-to-change-the-levels-of-ldl-and-hdl-in-their-blood.html

How does intake of unsaturated, saturated, and trans fats affect cholesterol levels and overall health?

Too much saturated, unsaturated, and trans fats and cause a person's LDL levels to increase. This could then lead to arterial hardening. If there is more LDL than HDL can uptake on, then a person could suffer from a heart attack or stroke. Unsaturated fats are called good fats because they can improve blood cholesterol levels, ease inflammation, stabilize heart rhythms, and play a number of other beneficial roles. Unsaturated fats are predominantly found in foods from plants, such as vegetable oils, nuts, and seeds. They are liquids at room temperature. Trans fatty acids, more commonly called trans fats, are made by heating liquid vegetable oils in the presence of hydrogen gas and a catalyst, a process called hydrogenation. Hydrogenation is used in restaurants and the food industry for frying, baked foods, and processed snack foods and margarines.


How does intake of unsaturated, saturated, and trans fats affect cholesterol levels in overall health? (n.d.). Retrieved from http://cholesterolinformationforyou.weebly.com/how-does-intake-of-unsaturated-saturated-and-trans-fats-affect-cholesterol-levels-in-overall-health.html