What are Roles of High-density lipoprotein – HDL?

Introduction of High-density lipoprotein

The cholesterol required by using peripheral tissues, along with vascular cells, is provided both by new synthesis in the cells and by a delivery from low-density lipoproteins (LDL). When the level of LDL is high, they accumulate in the artery wall where they’re oxidized and taken up by foam cells in a process that leads to the development and progression of atherosclerosis. High-density lipoproteins (HDL) oppose atherosclerosis directly, by removing cholesterol from foam cells, by inhibiting the oxidation of LDL, and by limiting the inflammatory processes that underlie atherosclerosis. HDL also has antithrombotic properties. As a result, HDL-cholesterol interrupts the process of atherogenesis at several key stages.

High-density lipoprotein

The cholesterol transported in high-density lipoprotein (HDL) is – ‘good’ cholesterol. One of the important functions of HDL is to transport cholesterol from the cells and tissue back to the liver. High HDL-cholesterol is good as it takes cholesterol out of cells and the blood and helps to prevent excess cholesterol. HDL also removes cholesterol deposited in the walls of blood vessels.

What is HDL?

HDL is the smallest and densest of the lipoproteins, containing the highest proportion of protein to cholesterol. In a normal healthy individual, HDL carries about 1 / 4 of the total amount of cholesterol inside the blood, whereas most of the remainder is carried in LDL (low-density lipoprotein) “bad cholesterol” particles. The framework of LDL is a single protein known as apolipoprotein B (Apo B), whereas HDL contains many proteins, the most important being apolipoprotein A1 (Apo A1). HDL is important for the synthesis of steroid hormones but it is better known for its protective role against cardiovascular disease.

A low HDL is thought to speed up the rate at which arteries fur up. HDL has 3 main benefits:-

  • High-density lipoprotein has a positive anti-oxidant effect, which helps protect blood cells and important chemical messengers in the blood from being broken down.
  • HDL removes excess cholesterol from the tissues and arteries, and returns it back to the liver for recycling and removal from the body, known as “reverse cholesterol transport”.
  • Also helps protects the artery walls against LDL cholesterol (an anti-inflammatory effect).

Together these effects prevent arteries from furring up. Atherosclerosis, specialist use this term to describe this process. It happens over many years and is caused by initial damage to the artery wall followed by fatty substances getting into the artery wall and causing fatty deposits known as plaques. Over time these fatty deposits can cause severe enough narrowing to reduce the flow of blood, or they can break up, causing sudden clots and blockages, resulting in heart attacks and strokes.

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What is the function of HDL?

HDL, the “good” cholesterol because it carries cholesterol to the liver, eliminates it from the body. High levels of HDL (especially over 60), believed to protect against heart disease, while low levels (less than 40) increase the risk of heart disease and possibly the risk of stroke.

Lipoproteins are complex chemicals that contain a core globule of fat surrounded by proteins – called apoproteins – that make them soluble in your body. Each class of lipoprotein contains different amounts and proportions of fats in the core, as well as specific apoproteins on their surface.

HDL, which stands for high-density lipoprotein, is the smallest and densest of the lipoproteins. The density of a lipoprotein depends on the relative amounts of lipid and protein in the particles. HDL is the densest lipoprotein because it contains a relatively low amount of fat compared to its protein content. HDL particles contain primarily cholesterol in their core and apoprotein A1 and A2 at their surface.

HDL Good or Bad?

It is a complex lipoprotein with a number of functions. One among its most essential function, as reverse cholesterol transport. As cells die, replaced by new cells, they release cholesterol into your blood. HDL binds the excess cholesterol and transfers it to other lipoproteins, such as LDL.

HDL, gets rid of cholesterol in the walls of your arteries and takes it to the liver, to remove it from your body through the intestines. Also called “good” cholesterol because of its protective effect against atherosclerosis – the build-up of fatty plaques in your arteries. Higher HDL concentrations correlate with lower rates of atherosclerosis and a lower risk for heart disease and stroke.

People who have naturally higher levels of HDL cholesterol are at lower risk of heart attacks and stroke. However, it’s less clear whether that same benefit holds true for people who increase their HDL levels with medications. Interventions known to increase HDL have shown to lower the risk of heart attacks, like exercise, quitting smoking or improving the diet. However, medications that specifically increase HDL have failed to reduce the rate of heart attacks.

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How to improve your HDL levels?

HDL levels are typically lower in people who have metabolic syndrome — a cluster of conditions that include obesity, increased blood pressure and high blood sugar levels.

  • Stop smoking
  • Limit animal fats (e.g. butter, cream, cheese, fried foods, Red meat)
  • Eat more fibre (e.g. fruit, vegetables, cereals, baked beans), follow the DASH diet.
  • Eat more fish
  • Drink less alcohol
  • Maintain a healthy weight
  • Increase physical activity – aim for 30 minutes or more of moderate intensity physical activity every day of the week

High-density lipoprotein

  • Take medicine every day as directed by your doctor – medication can help reduce your cholesterol if it’s too high


Cholesterol is a kind of fats, in the bloodstream. Your body needs a few cholesterols to work efficaciously. Cholesterol has many good uses but is a trouble when there’s an excessive amount of it inside the blood. High cholesterol can clog the blood vessels that supply the heart and different parts of the body.

This will reduce the flow of blood to the heart and cause a heart attack. Consult with you doctor about, risk factors and what you may do to reduce your risk of heart disorder. Often, the actions you are taking to control one risk component help reduce others as well.

For example, losing weight enables to reduce your blood cholesterol levels and high blood pressure, and helps to control diabetes. Physical activities assists, to lose weight and enhance the health of your heart and lungs, also help in lowering danger of heart disease.


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