What Causes Low HDL Cholesterol Levels?

There are a variety of factors that can cause your "good" high-density lipoprotein (HDL) cholesterol to be too low. These include genetic factors that you can't change and lifestyle factors that you can alter, including a high-fat diet, a lack of exercise, and smoking.

A low HDL count is a concern because it is linked to an increased risk of heart disease. The same is true if your "bad" low-density lipoprotein (LDL) cholesterol is high. Together, a low HDL and high LDL place you at increased risk of having a heart attack or stroke.

This article explains the causes of low HDL, what the optimal levels are, and how HDL plays a role in your overall health. It also covers ways to raise your HDL levels.

Causes of Low HDL

There are factors that cause your HDL to drop below the expected range of values (referred to as HDL deficiency). These include non-modifiable elements you can't control and modifiable ones that you can control.

There are five key factors linked specifically to HDL deficiency:

Genetic Mutations

Sometimes, a very low HDL count is caused by genes that run in families. These include conditions like Tangier’s disease, caused by mutations in the ABCA1 gene, and another called familial hypoalphalipoproteinemia, caused by mutations of the APOA1, ABCA1, or LCAT genes.

Excess Weight

If you are overweight or have obesity, a type of blood fat called triglycerides will increase. HDL is composed of triglycerides and, when triglyceride levels are high, HDL will undergo changes that cause it to break down faster, leading to a lower count.

If you are overweight or have obesity, losing 5% of your body weight is a reasonable short-term goal. Over the longer term, losing 15% of your body weight and remaining at this weight is considered a good result.

Working with a healthcare provider, personal trainer, and/or nutritionist can ensure that the weight-loss plan is safe and effective.

Poor Diet

A diet high in refined carbohydrates (such as white bread and sugar) causes the liver to produce more triglycerides, resulting in a drop in HDL.

Some foods you eat are also rich in triglycerides, including fried foods, processed foods, red meat, high-fat dairy, and margarine. Dietary triglycerides also affect HDL counts.

To counter this, limit your intake of refined carbs and saturated fats (found in animal-derived foods) and substitute with whole grains and healthier monounsaturated and polyunsaturated fats, (found in plant-based foods).

Inactivity

A lack of exercise is associated with the buildup of fatty deposits in arteries called atherosclerosis. Exercise improves HDL's ability to scoop up these fatty deposits and move them to the liver for disposal (a process known as cholesterol efflux).

Aerobic exercise is known to increase HDL levels in a dose–dependent manner. Studies have shown that the duration of aerobic exercise, as opposed to intensity, is the main factor associated with the increase.

To counter this, try doing aerobic exercises 40 minutes a day, three or four times a week. These include swimming, brisk walking, running, bicycling, and dancing.

Smoking

The chemicals in tobacco smoke can lower HDL levels in different ways. They reduce proteins called cholesterol ester transfer protein (CETP) and fats called lecithin, both of which are needed to build HDL. Smoking also impairs the liver's ability to clear excess triglycerides from the blood.

Quitting cigarettes can be hard, but speak with your healthcare provider about smoking cession aids, many of which are fully covered by health insurance under the Affordable Care Act.

Uncontrolled Diabetes

Hyperglycemia (high blood sugar) caused by poorly controlled diabetes can lead to the breakdown of a protein called apolipoprotein AI (ApoA-I) that makes up HDL particles, causing levels to drop.

Hyperglycemia also triggers a process called glycation in which excess sugar molecules bind to proteins in HDL and, by doing so, reduce cholesterol efflux and the overall function of HDL.

If you cannot manage your blood sugar, speak with your healthcare provider. Your condition may improve if you make strategic changes to your diet, increase your exercise routine, and improve your adherence to treatment. An adjustment of your medication or medication dose may also help.

Medicines

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

These include:

• Beta-blockers: Most often used to treat irregular heartbeats and angina
• Thiazide diuretics: A type of "water pill" used to treat high blood pressure
• Androgens: Male hormones, most specifically testosterone
• Progesterone: Commonly used in hormonal birth control
• Anabolic steroids: Used for rapid muscle growth and bodybuilding

Do not stop any prescribed drug or alter the dose without first speaking with your healthcare provider.

Why HDL Matters

HDL removes cholesterol from your arteries and takes it to the liver to be removed from the body. By doing so, it protects you from clogged arteries that lead to a heart attack or stroke.

Studies have shown that low HDL cholesterol levels are linked to an increased risk of heart disease. This is especially true if other fats (lipids) in your blood are high, including LDL cholesterol and triglycerides.

Research also suggests that, to a certain extent, high HDL levels are linked to a lower risk of heart disease.

Optimal HDL Levels

Cholesterol levels are checked with a simple blood test called a lipid panel. HDL counts are described in milligrams per deciliter of blood (mg/dL).

Optimal HDL levels can vary by a person's age and/or assigned sex at birth, as follows:

• People 19 and under: Greater than 45 mg/dL
• Males over 20: Greater than 40 mg/dL
• Females over 20: Greater than 50 mg/dL

Anything below these values is considered HDL deficiency.

In interpreting the results, healthcare providers tend to focus less on the actual HDL number and more on how it factors into your 10-year and lifelong risk of heart disease. This is referred to as a cardiovascular risk assessment.

The assessment involves not only modifiable and non-modifiable risk factors for heart disease but also social and economic factors that can influence your overall risk.

Depending on the methodology used, the assessment may include:

• Your age
• Your assigned sex at birth
• Your family history of heart disease
• Your personal history of heart disease
• Your blood pressure
• Your blood glucose
• Your body mass index (BMI)
• Your HDL count
• Your total cholesterol count
• Your smoking status
• Your diet
• Your stress levels
• Your exercise levels
• Your socioeconomic status

While an HDL count only offers a glimpse into your overall health, it remains an important tool by which to determine your short- and long-term risk of heart attack and stroke.

The HDL count also directs which actions should be taken to reduce your risk, including smoking cessation, changes in diet, and medications called statins used to reduce "bad" cholesterol.

Cholesterol Healthcare Provider Discussion Guide

Get our printable guide for your next healthcare provider's appointment to help you ask the right questions.

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Summary

HDL is the "good" cholesterol that helps remove cholesterol from your arteries. Higher levels are considered better for heart health. Normal levels are at least 40md/dL for adult males and 50 mg/dL for adult males.

Your HDL level is important, but your healthcare provider will likely focus less on the number and more on what it indicates. That may mean lifestyle changes, which can put you in control of your weight, diet, smoking habits, and other contributing factors.