Understanding Cholesterol

(Cholesterol, LDL, HDL)

What is cholesterol and where does it come from?

Cholesterol is a substance which is made in the body by the liver but is also found in some foods. It plays a vital role in how every cell works and is also needed to make Vitamin D, some hormones and bile for digestion. However, too much cholesterol in the blood can increase your risk of getting heart and circulatory diseases. Cholesterol is carried in the blood attached to proteins called lipoproteins. There are two main forms, LDL and HDL.

What is LDL and HDL?

LDL cholesterol can build up on the walls of your arteries and increase your chances of getting heart disease. That is why LDL cholesterol is referred to as "bad" cholesterol. The lower your LDL cholesterol number, the lower your risk.If your LDL is 190 or more, it is considered very high.When it comes to HDL cholesterol -- "good" cholesterol – a higher number means lower risk. This is because HDL cholesterol protects against heart disease by taking the "bad" cholesterol out of your blood and keeping it from building up in your arteries. A statin can slightly increase your HDL, as can exercise.

Difference between LDL and HDL

LDL structure is composed of around 50% cholesterol and 25% protein. LDL molecules are much smaller and denser than HDL molecules. Since they are smaller and less dense, they are more likely to go through oxidation and accumulate on on arterial walls as plaque. LDL proteins contain "B-100" proteins. HDL contain mainly A-1 and A-II proteins.The main function of LDL is to carry cholesterol to different parts of the body. Since it takes cholesterol to different parts of the body, it is more likely to build up on arterial walls. This leads to an increased risk of heart disease.HDL's main function is to take cholesterol from your heart and other organs to the liver to be disposed of.

Why do doctors monitor the concentrations of LDL and HDL in patient's blood?

During a blood test, LDL and HDL are both monitored along with other things because they are used to help evaluate the patient's risk of heart disease. Whether more cholesterol is being taken to or from cells can be determined during a blood test. HDL levels should be at least 40mg/dL or closer to 60mg/dL. LDL should be lower than 129mg/dL or even lower for people that are at higher risks for heart disease.

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

An excess of LDL can result in plaque buildup on arterial walls which can ultimately result in atheroscerlosis. That is the hardening of the arteries and can lead to heart diseases like a heart attack or stroke. Unlike LDL, higher HDL levels can actually lower the risk of heart disease.

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

A healthy diet with reduced fat and cholesterol will increase HDL levels and decrease LDL levels. Saturated fat intake should be limited 7% or less of total calories, cholesterol should be 200mg per day or less, and Omega 3 fatty acids will increase HDL levels. It has been found that physical activity can raise HDL levels 5%. The activity needs to be consistent with at least 30 minutes a day for 5 days a week. An estimated every six pounds that are lost can increase HDL by one and lower LDL by one. Medication can also be used with the other things above.