What are the main causes of low HDL levels?

Having high-density lipoprotein (HDL) cholesterol that is too low can increase your risk of heart disease and stroke, especially if your low-density lipoprotein (LDL) cholesterol is too high. This is because HDL protects your arteries by removing cholesterol and sending it to your liver for processing and excretion.

Some people have a genetic risk for cholesterol problems, but you can limit some of the risk factors when your good HDL is too low. Lifestyle changes including diet, exercise, and not smoking can help improve your levels. Medications can also help control your LDL lipoproteins.

There are seven main factors specifically linked to low HDL levels:

1. Genetic mutations

Sometimes, very low HDL is due to a genetic predisposition that runs in families. These include conditions such as Tangier disease, which is caused by mutations in the ABCA1 gene, and another condition called hereditary hypoalphalipoproteinemia, which is caused by mutations in the APOA1, ABCA1, or LCAT genes.

2. Being overweight

If you are overweight or have been diagnosed with obesity, a type of fat in your blood called triglycerides is elevated. HDL contains triglycerides, and when triglyceride levels are high, HDL undergoes changes that cause it to break down more quickly, resulting in lower numbers.

Losing 5% of your body weight is a reasonable short-term goal for addressing overweight and obesity. Long-term, losing 15% of your body weight and maintaining that weight is considered a good result. Some studies note that these goals vary from person to person.

Working with your healthcare provider, personal trainer, and/or dietitian can ensure that your weight loss plan is safe and effective.

3. Poor Diet

A diet high in refined carbohydrates (like white bread and sugar) causes the liver to produce more triglycerides, which lowers HDL. Some foods you eat are also high in triglycerides, including fried foods, processed foods, red meat, whole milk, and margarine.

To combat this, limit your intake of refined carbohydrates and saturated fats found in animal foods. Instead, replace them with whole grains and healthier monounsaturated and polyunsaturated fats found in plant foods.

4. Lack of exercise

Lack of exercise is linked to the buildup of fatty deposits in the arteries, a condition called atherosclerosis. Exercise improves HDL’s ability to collect these fatty deposits and transport them to the liver for processing (a process called cholesterol excretion).

To combat this, aim for 150 minutes of moderate-intensity exercise or 75 minutes of aerobic exercise each week. A combination of both could include moderate dancing or brisk walking, along with more vigorous jogging, faster cycling, or swimming.

5. Smoking

Chemicals in cigarette smoke can lower HDL levels in a number of ways, and studies have confirmed the impact of smoking on HDL. However, the exact reasons are not fully understood.

Quitting smoking can be difficult, but you can succeed. Talk to your healthcare provider about smoking cessation aids.

6. Uncontrolled diabetes

Low HDL levels and the risk of type 2 diabetes are strongly linked, although more research is needed to fully understand why.

Some research points to a role for apolipoprotein A1 (ApoA1), which is needed to make HDL, as it appears to influence the development of diabetes and other metabolic diseases. Low HDL levels seen in people with chronic kidney disease may also be linked to ApoA1.

Researchers are even looking at using treatments based on ApoA1 levels to control blood sugar in type 2 diabetes. It is important to avoid poorly controlled diabetes, so talk to your healthcare provider about any changes you may need to make to your diet, exercise, or diabetes medications.

7. Medications

Certain medications are known to lower HDL levels. Some of these medications are used to treat heart disease, while others affect hormones that can indirectly affect lipoprotein production.

These include: