Cholesterol- LDL and HDL

By Tashiara Nichols

What is it?

Cholesterol is carried in the blood attached to proteins called lipoproteins. There are two main forms, LDL (low density lipoprotein) and HDL (high density lipoprotein). These two forms are similar to good vs bad. The LDL cholesterol is often referred as bad cholesterol while, HDL cholesterol is referred as good cholesterol. LDL cholesterol is often referred to as "bad cholesterol" because too much is unhealthy. HDL is often referred to as “good cholesterol” because it is protective.

Cholesterol Functions:

  • Critical component of cell membranes.
  • Precursor to all steroid hormones.
  • A precursor to vitamin D.
  • The limiting factor that brain cells need to make connections with one another called synapses.

LDL Cholesterol

It contributes to plaque, a thick, hard deposit that can clog arteries and make them less flexible. This condition is known as atherosclerosis.


A clog could result in:


  • Heart Attack
  • Stroke
  • Peripheral artery disease

HDL Cholesterol

It helps remove LDL cholesterol from the arteries.It carries LDL cholesterol away from the arteries and back to the liver, where it is broken down and passed from the body.1/4 to 1/3 of blood cholesterol is carried by HDL.


A healthy level of HDL Cholesterol may protect against:



  • Heart Attacks
  • Stroke
  • Peripheral Artery Disease

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. They both transport cholesterol in the blood, but the main functional difference between the two is they deliver cholesterol to different parts of your body.


  • Also, the type of protein is significant because it determines the function of the lipoprotein particle.

Structure and Function of LDL Cholesterol

This is the primary carrier of cholesterol. It brings cholesterol to cells throughout your body and can cause cholesterol to build up within your arteries. Approximately 50% of the weight of an LDL particle is cholesterol and only 25% is protein. LDL particles are less than HDL particles. LDL Cholesterol also contains proteins called B-100 proteins.

Structure and Function of HDL Cholesterol

HDL 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. HDL particles consists of 20% cholesterol by weight and 50% protein. HDL particles are more dense than LDL particles. HDL Cholesterol contains mostly A-I and A-II proteins.

Why is it crucial for doctors to monitor the concentrations of LDL and HDL in patients’ blood?

Physicians monitor these two factors because their levels in the blood help doctors to evaluate a person’s health status and to determine whether a person is at risk for cardiovascular disease. Too much LDL in the bloodstream can result in cholesterol plaques forming. Doctors measure HDL because they need to make sure that the levels are high enough to promote good cardiovascular health.

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The Concentrations of LDL and HDL are Associated with the Risk for Heart Disease and Associated Disorders

High levels of LDL cholesterol lead to atherosclerosis increasing the risk of heart attack and ischemic stroke. HDL cholesterol reduces the risk of cardiovascular disease as it carries cholesterol away from the blood stream.

Other Molecules in a Patients' Blood That are Monitored Along with LDL and HDL

Lipoprotein analysis (lipoprotein profile or lipid profile) measures blood levels of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides. Triglycerides are a type of fat the body uses to store energy and give energy to muscles. Only small amounts are found in the blood. Having a high triglyceride level along with a high LDL cholesterol may increase your chances of having heart disease more than having only a high LDL cholesterol level.

Results of a Cholesterol Test

Your test report will show your cholesterol levels in milligrams per deciliter of blood (mg/dL). To determine how your cholesterol levels affect your risk of heart disease, your doctor will also take into account other risk factors such as age, family history, smoking and high blood pressure. Standard cholesterol test (called a "lipid panel") measures three specific kinds of fat: LDL, HDL and Triglycerides.


Your total cholesterol score is calculated using the following equation: HDL + LDL + 20 percent of your triglyceride level.


Desirable Blood Cholesterol --

  • Total blood cholesterol level less than 200 mg/dL.
  • HDL level 35 mg/dL or greater.
  • LDL level less than 130 mg/dL.

What Patients Can Do to Change their Levels of LDL and HDL in Their Blood

  • A healthy diet.
  • Saturated fat intake should be limited to 7% or less of total calories.
  • Cholesterol should be 200mg or less per day.
  • More Omega 3 fatty acids to increase HDL.
  • Exercise to increase HDL. At least 30 min a day over a total of 5 days a week.
  • Also, a variety of medicine can increase/ decrease HDL and LDL levels.

How does How Does the Intake of Unsaturated, Saturated, and Trans Fats affect Cholesterol Levels and Overall Health?

Too much saturated, unsaturated and trans fats can cause a person's LDL levels to increase. Which could be fatal.


Unsaturated Fats:


  1. Can improve blood cholesterol levels.
  2. Can ease inflammation.
  3. Can stabilize heart rhythms.
  4. And play a number of beneficial roles.
  • Only the Right Amount