There are two main types of cholesterol: LDL, or low-density lipoprotein, and HDL, or high-density lipoprotein. LDL is considered the "bad" cholesterol, and HDL is the "good" cholesterol. HDL is made up of more proteins and less lipids than LDL. HDL is good cholesterol because it removes cholesterol from circulation in the bloodstream and returns it back to the liver to be excreted or re-packaged.
Cholesterol Basics
Cholesterol comes from both your body and food. Your body's cholesterol is produced mainly by the liver; dietary cholesterol comes from only animal products. Cholesterol is involved in building and maintaining cellular membranes and is necessary for cell signaling, transport and nerve signaling. Cholesterol is made up of proteins and lipids. The density of proteins and lipids in the cholesterol molecule determines whether the cholesterol is "good" or "bad." LDL cholesterol is a low density lipoprotein, making it more harmful to the body because of its higher lipid, or fat, content. HDL cholesterol is a high density lipoprotein, which means it has a higher protein content than LDL and is more beneficial to the body.
Functions of HDL
HDL is a small, dense particle made up of mainly protein with some lipid particles. HDL can protect against atherosclerosis, or the thickening and hardening of the artery walls that can lead to heart attacks and stroke. In atherosclerosis, LDL cholesterol and fats build up in the artery walls and form plaque. HDL can remove the LDL and fats from the artery walls in order to lower the risk of atherosclerosis by preventing the build up of plaque. HDL also inhibits oxidation, platelet aggregation and inflammation, which helps protect against heart disease and stroke. HDL transports LDL from circulation back to the liver to be excreted or re-synthesized. The less LDL there is in circulation, the lower the risk for heart disease and its components, which are high blood pressure and high cholesterol.
Cholesterol Levels
You should aim for your total cholesterol to be less than 200 mg/dL. This number includes HDL and LDL levels. You want HDL levels to be high -- 60 mg/dL or higher, and LDL levels to be low -- less than 100 mg/dL. If HDL levels are less than 40 mg/dL, they are considered low. Doctors use cholesterol levels and the ratio of HDL to LDL to determine heart disease risk.
Increasing HDL Levels
You can increase HDL levels, and in turn decrease LDL levels, by making lifestyle changes through diet and exercise. Twenty to 30 minutes of aerobic exercise daily can increase HDL levels, as well as help you lose weight which also raises HDL levels. Even a small increase in HDL levels can decrease the risk for heart disease. Supplementing with omega-3 fatty acids or fish oils can increase HDL levels. Follow the dosage instruction on the supplement you choose. Adding sources of soluble fiber to your diet can also improve HDL levels and lower LDL levels. These types of food include oats, fruits and vegetables. You should consume 20 to 35 g of fiber daily, with at least 2 to 3 servings being from soluble fiber sources. Smoking cessation and alcohol in moderation can also improve HDL levels.
Drug Therapy
If lifestyle modifications are not enough to improve HDL levels and possibly lower LDL levels, you can turn to certain cholesterol-lowering medications. These medications will lower LDL levels, and in turn, increase HDL levels. Statins inhibit liver production of cholesterol. They lower LDL and have moderate effects on raising HDL. Fibrates have shown some effects of raising HDL levels and are usually paired with a statin. Niacin, or nicotinic acid, affects the liver and its production of blood fats to lower LDL and increase HDL.
