What is LDL (low-density lipoproteins)?

Introduction of low-density lipoproteins

Cholesterol isn’t simply something that sits on your body like fats around your waist. It’s carried through your bloodstream by using carriers made of fats (lipid) and proteins. Those are called – no big surprise – lipoproteins.

Types of lipoproteins carry cholesterol to and from cells. One is low-density lipoprotein or LDL. The other is high-density lipoprotein or HDL. The amount of each kind of cholesterol in your blood may be measured by a blood test.

LDL cholesterol is known as “bad” cholesterol. Consider it as less desirable or even lousy cholesterol, because it contributes to fatty build-ups in arteries (atherosclerosis). Plaque build-ups narrow arteries and raise the risk for heart attack, stroke and peripheral artery disease (narrowed arteries in the legs).

What is LDL (low-density lipoproteins) cholesterol?

LDL – low-density lipoprotein is said because it contains a low density of or low amount of proteins and is mostly fat. And labeled as the “bad cholesterol”, is a mixture of a moderate portion of proteins, a touch of triglycerides and a major percentage (approximately 50%) of cholesterol.

It is called the bad cholesterol because higher than normal LDL levels can give rise to serious health complications, which besides others include heart attack, stroke, and peripheral vascular disease. You find it especially in the blood, the tissue cells, and approximately 80% of it is produced in the liver. The body makes the rest of the 20% of the foods that we eat. LDL is a type of cholesterol, which again is a type of a lipid (fat).

Cholesterol, defined as the most common type of steroid compound in the body. It is a soft and waxy substance in nature and does not dissolve in blood. It, therefore, needs a vehicle or a carrier to transport itself through the blood. The soluble proteins in the blood do the task and help the cholesterol to reach the cells in the various parts of the body and carry out its functions, which incidentally are absolutely essential to us.

Cholesterol piggy rides on the protein to facilitate its transport via the blood and this combination is referred to as Lipoprotein (lipo meaning fat).Low-density lipoproteins transport the cholesterol from the liver through the blood for uptake by the body cells of various tissues. This helps in the formation of the cell wall and also keeps up the cell nutrition.

Types of Lipoproteins?

There are 3 main types of lipoproteins moving in the bloodstream:

  • LDL – Low-Density Lipoproteins, the bad cholesterol
  • HDL – high-Density Lipoproteins, the good cholesterol
  • VLDL –Very Low-Density Lipoproteins, once more the bad cholesterol

All these types of lipoproteins don’t simply carry the cholesterol, in addition, they also carry triglycerides, phospholipids, fat-soluble vitamins, antioxidants, and of course the proteins.

low-density lipoproteins

What are the level, structure, and functions of LDL?

LDL accommodates of 10% triglycerides, 45% cholesterol, 22% phospholipid, and 25% protein. As you can see, cholesterol makes up the majority of LDL. LDL particles average 22 nm in diameter with about 3000 lipid molecules in overall, and they contain about 170 triacylglycerols (a systematic chemical name for triglyceride), 1600 cholesterol esters, and 200 unesterified cholesterol molecules. Ester is nothing but organic compounds in which the hydrogen of the acid, replaced by an alkyl or another organic group.

LDL cholesterol is transforms into cholesteryl esters to more efficaciously transport both the dietary and synthesized cholesterol thru the bloodstream.  Free cholesterol, present in the lipoproteins only confines to the outer surface of the lipoprotein particle. It convertes into the form of cholesteryl esters and it is being packed into the interior of the lipoprotein particle. This vastly increases the capacity of lipoproteins to transport cholesterol via the blood.

In 2004, a panel of physicians lowered the “safe” level of LDL cholesterol from 130 to 100 mg/dL and further recommended that people who are at high risk of developing cardiovascular disease should aim to lower their LDL levels to 70 mg/dL.

LDL cholesterol levels after 9 to 12-hour fasting as per the Adult Treatment Panel III (ATP III) guidelines are as follows:-

  • 100 mg/ dL – Optimal
  • 100-129 mg/dL – Near-optimal
  • 130-159 mg/dL – Borderline high
  • 160-189 mg/dL – High
  • 190 mg/dL – Very high

LDL is the primary cholesterol transporter in your bloodstream. Your body uses cholesterol to produce protective walls around your cells and steroid hormones – chemicals that help control many body functions. After delivering cholesterol to your tissues, most of the remaining LDL, your liver removes it or take it up by scavenger cells called macrophages. Too much LDL causes a number of problems.

For example, LDL particles and the macrophages that engulf them can bind to your artery walls. This sets off a cascade of events that may lead to the formation of atherosclerotic plaques, which can grow over time and clog your arteries. LDL – referred to as “bad” cholesterol because elevated levels, associated with a higher rate of atherosclerosis and cardiovascular disease risk increases .

Functions of LDL in brief:-

  • LDL Cholesterol helps to synthesize vitamin D in the skin from sunlight exposure.
  • The precursor to the production of the steroid hormone pregnenolone.
  • It plays a vital role in cognitive function.
  • LDL helps in the formation of the cell wall.
  • It helps in the absorption of fat-soluble vitamins A, D, E, and K. Without LDL cholesterol, your body will deprive, of these essential vitamins.
  • LDL plays a vital role in nerve cells (neurons) communicating with each other and exchanging electrical signals.

However, letting your LDL blood levels rise is definitely something you do not want, just keep those levels within healthy limits and let the LDL do its job.

The non-medical or natural ways to lower LDL cholesterol levels include:-


  • Avoid high saturated fat foods
  • Follow the low cholesterol diet
  • Aerobic exercise daily
  • Have a healthy lifestyle
  • Eat natural foods that have cholesterol-lowering properties.

low-density lipoproteins


Because of its “badness”, high levels of LDL need to be lowered and taken down within its normal blood levels. There are medical methods to do it with drugs and there are non-medical or natural ways to do it. Individual give first preference to the non-medical way because cholesterol medication (statins) once start growing, grows to be a lifelong commitment and secondly, and have side effects which include liver and muscle damage plus neurological problems.

Very high LDL levels, also require treatment with medication without delay. The American heart association describes the parameters of LDL levels and the risk factors in patients who should start with statins immediately.

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