Cholesterol travels through your blood in packages called lipoproteins. Lipoproteins contain a fat component and a protein component. Apolipoproteins form the protein component of a lipoprotein and lipids form the fat component. HDL and LDL particles are two kinds of lipoproteins and both transport cholesterol. However, each of these lipoproteins has different transport functions in your body.
HDL Form and Function
HDL stands for high-density lipoprotein. The diameter of HDL particles ranges from eight to 11 nm. HDLs are the smallest and most dense lipoproteins in your body and contain a higher proportion of protein than other lipoproteins. HDLs circulate through your bloodstream and increase in size as they travel and pick up excess cholesterol. Cholesterol-carrying HDL packages move cholesterol from your body tissues to your liver. Your liver removes cholesterol from HDL particles and uses the cholesterol to make bile fluid. According to the Harvard Health website, HDLs may reduce your risk of heart disease because they can promote excretion of excess cholesterol by taking it to your liver. Higher HDL cholesterol levels may reduce your risk of premature coronary heart disease. HDL particles also transport other apolipoproteins to and from lipoproteins during lipoprotein catabolism, a metabolic process that involves breaking down lipoproteins. HDL particles contain antioxidant molecules that may prevent the formation of other lipoproteins that can cause heart disease.
LDL Form and Function
LDL stands for low-density lipoprotein. The diameter of these particles ranges from 18 to 25 nm. Unlike HDLs, LDL particles transport cholesterol to extrahepatic tissues, which are body tissues outside of your liver. The Harvard Health website reports that LDL particles carry 60 to 70 percent of your cholesterol to parts of your body that need it but too much LDL is undesirable, because LDLs deposit cholesterol in your arteries. Cholesterol deposits in your arteries can form plaques that can cause blockages and heart attacks or make your arteries harder. LDL particles are known as "bad" cholesterol, because excessively high LDL levels increase your risk for these undesirable effects.
Healthy Levels
Your doctor can determine your HDL and LDL levels by performing a fasting cholesterol screening. Higher HDL and lower LDL levels promote optimum health. According to the American Heart Association, a man's risk for heart disease increases when his HDL levels fall below 40 mg/dL and a woman's risk goes up if her HDL levels fall below 50 mg/dL. Other risk factors for heart disease and stroke help determine what LDL level is necessary for optimum health, so you should discuss your levels and risk factors with your doctor. Generally, optimal LDL levels are below 100 mg/dL.
Controlling HDL
According to the American Heart Association, lifestyle practices affect your HDL levels. Foods that contain trans fatty acids can reduce your HDL levels. Obesity and smoking may also lower your HDL levels. You can increase your HDL levels by performing 30 to 60 minutes of regular physical activity most days of the week. Exercise and practicing a balanced diet can help your body produce more HDLs. Your healthcare practitioner may prescribe medication that specifically increases your HDL levels if lifestyle changes are not adequate.
Controlling LDL
Genetics can predispose someone to have unhealthy or particularly high LDL levels. Lifestyle modifications and medication can help control your LDLs. Your diet also influences your LDL levels. According to the Harvard Health website, you may be able to reduce your LDL levels by practicing a reduced-fat diet. You may be able to lower your LDL levels by reducing or eliminating foods that contain saturated fat, trans fat and dietary cholesterol from your diet.
