HDL, which is short for high-density lipoprotein, is the type of cholesterol often referred to as "good" cholesterol, because as it travels through the bloodstream, it removes the "bad" low-density lipoprotein cholesterol, explains WebMD. High levels of LDL cholesterol increase a person's chances of having a heart attack.
HDL cholesterol acts like a scavenger, collecting the LDL cholesterol from where it can cause harm, and transporting it to the liver, which reprocesses it, according to WebMD. HDL helps to reduce the risk of heart attacks and strokes by preventing atherosclerosis, which causes them. Atherosclerosis begins to occur when the inner walls of the blood vessels, known as endothelium, are damaged. HDL maintains the health of the endothelium by scrubbing it clean.
A person's cholesterol level is considered high if it is greater than 60 milligrams per deciliter, and low if it is less than 40 milligrams per deciliter. People with high levels of HDL are generally at lower risk for heart disease than those with low levels, states WebMD.
HDL levels can be raised by exercising for 30 to 60 minutes a day most days of the week. Maintaining a healthy weight can have the same effect. Because tobacco smoke lowers HDL, quitting smoking can increase a person's HDL levels, says WebMD.