High density lipoprotein (HDL) is a type of lipoprotein particle that transports cholesterol through the bloodstream from peripheral tissues back to the liver, where it can be processed and excreted. This reverse cholesterol transport mechanism is thought to be one of the key ways in which HDL protects against coronary artery disease, which is why it is often referred to as ‘good cholesterol.’
Higher levels of HDL cholesterol are associated with a lower risk of heart attack and cardiac arrest. Conversely, a low HDL level (below 1.0 mmol/L in men and below 1.2 mmol/L in women) is considered an independent cardiovascular risk factor. Low HDL is often found alongside high triglycerides and abdominal obesity, a pattern associated with type 2 diabetes and metabolic syndrome.
HDL levels are raised by regular aerobic exercise, stopping smoking, and in some people by medications such as fibrates or niacin. Statins, which are primarily used to lower LDL cholesterol, have a modest effect on raising HDL.
While higher HDL is generally beneficial, some genetic conditions cause very high HDL levels that paradoxically do not protect against cardiovascular disease, suggesting that HDL functionality (how well it transports cholesterol) matters as much as the measured level. HDL is routinely measured as part of a full fasting lipid profile alongside total cholesterol, LDL cholesterol, and triglycerides.
« Back to Glossary Index