HDL and LDL are the common abbreviations for the two types of compounds that carry blood cholesterol. Cholesterol produced in the liver cells must travel through the blood to get to cells throughout the body. Because cholesterol is a fatty substance and blood is 78 percent water, the two cannot mix together. Therefore specialized proteins known as lipoproteins bind to the cholesterol to carry it in the blood. Hhigh-density lipoprotein known as HDL carries about one-third to one-fourth of the body's cholesterol supply while low-density lipoprotine, LDL, carries the majority of it.
Role of HDL
Doctors often refer to HDL as the "good" cholesterol because of the role it plays in the body. The HDL carries the cholesterol bound to it back to the liver where it gets broken down and excreted from the body in the waste. Because HDL removes cholesterol from the body, you want your HDL levels to increase because higher levels actually protect against heart disease.
Role of LDL
In contrast, the cholesterol bound to LDL remains in the blood, giving it the label of "bad" cholesterol. When doctors stress the importance of lowering your cholesterol levels to promote a healthy heart, they are referring to the LDL levels. Because your body makes all the cholesterol it needs to support normal functions, the dietary cholesterol and fats you consume in foods can lead to high blood cholesterol levels.
Relationship
HDL and LDL exhibit an inverse relationship because, typically, as LDL levels increase, HDL levels drop. Consuming too much saturated fat and trans fat not only increases the level of LDL but also decreases the level of HDL. Because your body needs some fat, make sure the majority of your fat intake consists of unsaturated fats, which are known to decrease LDL levels and increase HDL levels. Smoking, a major risk factor for heart disease, decreases your HDL level which increases the portion of LDL in the total cholesterol. Factors that increase your HDL levels help to reduce your LDL levels, therefore decreasing your overall risk for heart disease. Participating in regular physical activity helps to increase HDL levels. In addition, consuming foods that contain omega-3 fatty acids, such as nuts and fish, can help to increase HDL levels.
Healthy Cholesterol Levels
Your total cholesterol -- the amount of HDL and LDL added together -- should remain less than 200 mg/dL for optimal heart health. As your total cholesterol reaches more than 240 mg/dL, your risk of developing heart disease increases. The relationship of HDL and LDL plays a major role in obtaining and maintaining healthy cholesterol levels. For optimal heart health maintain your LDL level at less than 100 mg/dL. LDL levels of 130 mg/dL to 159 mg/dL borderline on high while those over 160 mg/dL can lead to additional health problems. HDL levels that fall below 40 mg/dL contribute to heart disease while those levels at 60 mg/dL or higher actually protect against heart disease.
