HDL, LDL and triglycerides are various types of lipids that circulate throughout your bloodstream. They perform several important functions in your body, but excess amounts of them can be harmful to your health. Your doctor can perform a blood test called a lipid profile to determine how much of each lipid your blood contains and determine whether you are at risk of heart disease.
Physiology
Cholesterol is carried throughout your body in transportation structures called lipoproteins. Lipoproteins have two compartments: inner and outer. The outer compartment is made up of proteins and phospholipids. The inner compartment contains cholesterol and other insoluble fats. Lipoproteins are categorized based on their ratio of protein and cholesterol, or their density. LDL, or low-density lipoprotein, contains small amounts of protein and large amounts of cholesterol. HDL, or high-density lipoprotein, contains large amounts of protein and small amounts of cholesterol.
LDL
The main function of LDL is to deliver cholesterol to your cells. This cholesterol is vital for allowing your body to build cell membranes and ensuring that you can synthesize bile acids, vitamin D and the sex hormones estrogen and testosterone. If you have too much LDL, however, cholesterol may deposit in your arteries and accumulate on your arterial walls, promoting atherosclerosis and increasing your risk of heart disease. An ideal LDL level for healthy individuals is below 100 mg/dL. If you have heart disease already, it is best to keep your LDL below 70 mg/dL.
HDL
The main function of HDL is to remove excess cholesterol from your blood. Because of this, HDL is considered protective against heart disease and the goal is to get your HDL numbers as high as possible. Adult men and women should have HDL levels 60 mg/dL or higher. If a man's level falls below 40 mg/dL and a woman's level falls below 50 mg/dL, it is considered poor.
Triglycerides
Triglycerides are the chemical storage form of fat in your food and your body. Your body uses triglycerides as a form of energy when your intake of calories falls short. If your blood contains too many triglycerides, however, it can increase your risk of heart disease. An ideal triglyceride level is less than 150 mg/dL. If your triglyceride levels reach 150 to 199 mg/dL, they are considered borderline high. Triglyceride between 200 and 499 mg/dL are classified as high and levels that exceed 499 mg/dL are very high.
References
- MayoClinic.com: High Cholesterol
- American Heart Association: Triglycerides
- "Nutrition and You"; Joan Salge Blake; 2008
