The Causes and Effects of Oxidized LDL Cholesterol

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Oxidized low-density lipoprotein (LDL) is a harmful type of cholesterol that is produced in your body when normal LDL cholesterol is damaged by chemical interactions with free radicals. These and a related series of inflammatory responses can result in atherosclerosis, which is the hardening of the arteries. The resulting decrease in blood flow in your arteries increases your chances of having a heart attack or a stroke. You can produce high levels of oxidized LDL if you have excessive free radical formation or simply high LDL cholesterol levels. 

How Oxidized LDL Forms

The oxidation of LDL is thought to occur when LDL cholesterol particles in your body react with free radicals, which are unstable molecules that are produced as a result of normal metabolism, a disease, or exposure to toxins.

Free radicals cause oxidation, a type of chemical destabilization of molecules such as LDL cholesterol. The oxidized LDL itself then becomes more reactive with the surrounding tissues, which can produce inflammation that leads to disease and organ damage. In particular, oxidized LDL is a threat to your cardiovascular health.

LDL cholesterol molecules are not all the same size, and some are larger than others. Smaller LDL particles are more likely to become oxidized, making them more detrimental to your health.

Some risk factors that appear to increase the levels of oxidized LDL include:

  • Consuming a diet that is high in trans fats
  • Smoking
  • Poorly controlled diabetes
  • Metabolic syndrome, which is often a precursor of diabetes
  • Exposure to toxins through pollution and preservatives
  • Stress

Once LDL becomes oxidized, it inhabits the endothelium (inner lining) of the arteries in the body, such as the carotid arteries, the coronary arteries, or the arteries that supply your legs and arms with blood.

The Effects of Oxidized LDL

The inflammation in the arteries produced by oxidized LDL is dangerous since these blood vessels carry blood to all of your organs and tissues. It promotes atherosclerosis and increases your risk of having a heart attack or a stroke.

LDL cholesterol in the endothelial lining of the arteries promotes the accumulation of inflammatory cells, such as lymphocytes (white blood cells), dendritic cells (immune cells), and macrophages (inflammatory cells) at the site of your blood vessels. Platelets, which normally help to stop bleeding by producing blood clots, can stick to these areas of inflammation within the arteries, creating plaques, which are hardened areas inside a blood vessel. More macrophages, cholesterol, and other lipids begin to accumulate at the site, which is usually sticky, allowing the plaques to grow larger. 

Over time, this can partially or completely restrict blood flow within an artery, resulting in a variety of health conditions, including coronary heart disease, peripheral vascular disease, or cerebrovascular disease. 


Routine cholesterol blood tests can measure your LDL, HDL (the good cholesterol), and triglyceride levels, but they do not measure the concentration of small versus large LDL molecules or oxidized LDL levels. 

There are some things you can do to reduce your level of small LDL and to prevent the formation of oxidized LDL:

  • Work to lower your overall LDL cholesterol level. In some cases, you may need medication to do this. Some cholesterol-lowering medications, such as statins, also possess anti-inflammatory properties that may also help prevent the inflammation that promotes atherosclerosis.
  • If you smoke, stop, and don't pick up the habit if you're already smoke-free. Smoking exposes you to chemicals that promote free radical formation, increasing oxidative damage. 
  • Exclude trans fats from your diet. Food that may contain trans fats include pastries, deep-fried foods, potato chips, and other foods cooked with lard.
  • Add fruits and vegetables to your diet, which are rich in antioxidants with natural anti-inflammatory properties that may help to reduce the oxidation of LDL.
  • If you have been diagnosed with diabetes or metabolic syndrome, aim to keep your blood sugar under control. You can do this by losing weight, eating healthy, and exercising. If lifestyle changes are not enough to manage your blood sugar level, your doctor may prescribe medications to control these conditions.
  • Try to raise your HDL levels, as this "good cholesterol" is believed to have an antioxidant effect because of its ability to deactivate lipid hydroperoxide, an enzyme that plays a role in the oxidation of LDL cholesterol. In general, exercise and eating healthy fats, which are found in nuts, avocados, and seafood, are associated with optimal HDL levels.

A Word From Verywell

High LDL cholesterol levels can place you at risk for developing cardiovascular disease, and the type of LDL circulating in your blood matters. Oxidized LDL is increasingly recognized as a contributor to heart disease, vascular disease, and stroke.

It is generally not considered helpful to do a specialized test to measure oxidized LDL. Levels of oxidized LDL generally correlate with the presence of other, easily detected risk factors, such as those listed above. Actually measuring oxidized LDL, therefore, usually doesn't add much to your doctor's ability to estimate your overall cardiovascular risk.

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