Can Your Good Cholesterol Go Bad?

by and | Updated May 22, 2023 | Blood Vessels & Heart Health, Heart Health

Nearly half of the people who get heart attacks have healthy cholesterol levels. Up to 65% of cardiovascular deaths cannot be prevented by assumed or supposed LDL-C lowering agents.1 Multiple clinical studies have identified individuals with a significant coronary artery disease despite normal or elevated levels of HDL. Conversely, some populations with very low levels of HDL-C have paradoxically lower rates of heart disease.2 Why?

Some Cholesterol is Good

Your body needs a certain amount of cholesterol for the cell membranes, nerve insulation, and steroid hormones (sex hormones, cortisol, and vitamin D hormone). In fact, it makes all you need. You just don’t want it to clog your arteries or suppress your immune system as it becomes oxidized. Since cholesterol cannot dissolve in water, it is carried by trucks known as lipoproteins in the blood. Low-density lipoproteins (LDLs) take cholesterol to the cells and blood vessels. We need a certain amount of LDLs. An elevated LDL level, however, is a risk factor for coronary artery disease. HDLs (high density lipoproteins), as little trucks, transport cholesterol from your arteries to your liver. Put simply, HDL fights the “bad” cholesterol. HDL is a family; some members protect from bad cholesterol, whereas others do not. HDL-C is protective against heart disease under certain circumstances.

HDL Contributions:

High-density lipoproteins are super heroes, right? After all, HDLs defend the arteries from cholesterol build up.

  • They act as cholesterol scavengers, pull cholesterol out of arteries, and carry cholesterol to the liver where it is converted into bile.
  • HDLs exert anti-inflammatory activity.3 (Inflammation plays a major role in atherosclerosis.)
  • HDLs also protect the innermost lining (endothelium) of arteries and reduce the risk of undesirable clot formation.4
  • They stimulate the production of nitric oxide.5 In moderation, nitric oxide improves the ability of blood vessels to dilate.
  • HDLs protect from free radical damage. Normal HDL helps to reduce oxidation of cholesterol. Oxidized cholesterol is toxic to the lining inside the arteries and suppresses the immune system.

Know Your Numbers, But Don’t Get Fooled

According to the Mayo Clinic your “good” cholesterol (HDL) should be 40 to 49 mg/dL if you are a man and 50 to 59 mg/dL if you are a woman. Above 60 is ideal for HDL. A low HDL is considered as under 40 milligrams per deciliter of blood (mg/dL). High levels of HDL are generally associated with lower risks for stroke and heart disease whereas lower levels are associated with a substantial increased risk. As mentioned in our first paragraph, this might not always be true. In fact, just measuring the HDL-C level is probably not a good predictor of its cardiovascular benefits. Methods to evaluate HDL functions are required.6,7,8 Hold tight because in a few minutes we will address the lifestyle factors and medical conditions that can turn your good HDLs into dysfunctional HDLs.

Lifestyle Factors That Increase HDL:

  • Stop smoking. Quitting smoking can increase your HDL cholesterol by up to 10 percent.9
  • Weight loss (if obese). For every 6 pounds (2.7 kilograms) you lose, your HDL may increase by 1 mg/dL (0.03 mmol/L).10
  • Regular or frequent aerobic exercise can increase HDL cholesterol by about 5 percent in otherwise healthy, sedentary adults.11
  • Garlic, onions, and chromium help increase HDL.
  • Monounsaturated and polyunsaturated fats — found in olive, peanut, and canola oils — tend to improve HDL’s anti-inflammatory abilities.

Please note: Inflammation is involved in all the developmental stages of atherosclerosis. Just reducing elevated LDL cholesterol levels without reducing the inflammation is not going to get at the problem sufficiently. Inflammation must also be confronted. Fortunately, many of the same lifestyle strategies that reduce cholesterol also exert a beneficial anti-inflammatory effect. One caveat though: No vitamin pill can replace the thousands of antioxidants and anti-inflammatory compounds found in plant foods!

Good Guys Turned Into Villains

The quality of HDL can be compromised. Unfortunately, under some conditions HDLs become dysfunctional and can actually promote atherosclerosis instead of protecting the arteries from it.12

Oxidized cholesterol pushes inflammation inside the arteries and encourages the development of atherosclerosis. Even though HDL is considered protective against atherosclerosis, HDL itself can become oxidized from smoking, a deficient diet, or a pro-inflammatory condition such as obesity, pre-diabetes, and diabetes. When HDL becomes oxidized, it becomes dysfunctional and cannot remove cholesterol from arteries. It loses its ability to protect cholesterol from oxidation. Dysfunctional HDL-C does not promote heart and blood vessel health even if HDL-C is present in high levels.13

Dysfunctional HDLs, especially when coupled with oxidized LDL, accelerate the development of atherosclerosis. This duo also increases the risk for undesirable clot formation. As we will soon see, a person’s diet and medical history should be carefully evaluated even when the cholesterol numbers are within normal levels.

What Causes HDL to Turn Bad?


In both metabolic syndrome and diabetes mellitus, the HDL particles undergo diverse structural modifications that change its function.14


Inflammation from influenza, infections, and other diseases can change and profoundly transform athero-protective HDLs to pro-atherogenic HDLs.15,16

Lipid Peroxides

The lipid classification includes fats, cholesterol, and phosphor-lipids. Free radicals damage fats. When fats are oxidized, they produce lipid peroxides and more free radicals that alter HDL function.17

One way to reduce this lipid peroxidation is to use cold-pressed, virgin, vegetable oils rather than regular commercial oil. The more an oil is heated, the more lipid peroxides are produced. Oxidation attacks the double bonds of fats, so monounsaturated fats like oleic acid in olives and plant-based omega-3 fats are superior to fish oil, for most people, because they have only one double bond.18 Fat-soluble antioxidants also help to reduce lipid peroxides.

Cigarette Smoking

Not only does smoking lower the HDL level, it can strip the protective portions of HDL. LCAT is an enzyme that is crucial for the maintenance of normal HDL metabolism. Smoking decreases LCAT. Smoking also encourages lipid peroxidation.19

Intake of Fats

Consumption of saturated fats reduces the anti-inflammatory potential of HDL and impairs the ability of blood vessels to dilate. In contrast, the anti-inflammatory activity of HDL improves after consumption of polyunsaturated fat.20

Medical Conditions

Besides pre-diabetes and diabetes, other medical conditions can convert our HDL superheroes into HDL villains. Certain auto-immune conditions: lupus erythematosus, rheumatoid arthritis, scleroderma can change the anti-inflammatory HDL into a pro-inflammatory HDL.21 Obstructive sleep apnea can also contribute to HDL dysfunction.

Elevated Homocysteine Levels

A high meat diet, deficiency in B12 and folic acid, low thyroid hormone, and kidney disease can elevate homocysteine levels. An elevated homocysteine level promotes both dysfunctional HDL and pushes inflammation inside the artery. 22

Environmental Pollutants

Breathing motor vehicle emissions triggers a change in high-density lipoprotein (HDL) cholesterol, altering its cardiovascular protective qualities so that it actually contributes to clogged arteries.23


Do you know your risk factors for coronary artery disease? Although your HDL number is important, it can fool you into false security if you have any condition that renders HDLs dysfunctional. Healthful lifestyle strategies can help to prevent and reverse atherosclerosis. Please work with your doctor and health care team to correct any unhealthy lifestyle practices and get any needed treatments.

© 2023, Wildwood Sanitarium. All rights reserved.

Disclaimer: The information in this article is helpful and is educational. It is not the author’s or authors’ or Wildwood Health Institute’s intent to substitute the blog article for diagnosis, counseling, or treatment by a qualified health professional.


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© 2023, Wildwood Sanitarium. All rights reserved.

Disclaimer: The information in this article is educational and general in nature. Neither Wildwood Lifestyle Center, its entities, nor author intend this article as a substitute for medical diagnosis, counsel, or treatment by a qualified health professional.

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