HDL cholesterol has been referred to for years as the “good” cholesterol. High levels of HDL cholesterol have been associated with decreased risk of heart disease. There are no medications available that improve our HDL cholesterol and result in decreased risk of heart disease. And yet, I get asked time and again by patients how to raise their HDL cholesterol. So, should we be worried about low HDL cholesterol? Should we work on lifestyle factors that can increase good cholesterol?

What is HDL cholesterol? What are optimal levels?

High-density lipoprotein (HDL) particles are small, cholesterol carrying particles that typically carry cholesterol away from the arteries and back to the liver, where it can be broken down and eventually eliminated from the body. HDL may also protect against inflammation and oxidation of bad cholesterol.

The HDL cholesterol number that you see on your lipid panel is the amount of cholesterol contained within these HDL particles. HDL cholesterol is considered to be low when it is < 50 mg/dL in women and < 40 mg/dL in men.

What causes low HDL cholesterol?

HDL cholesterol is frequently genetically determined

Other causes of low HDL cholesterol include smoking, diabetes, and poor physical fitness. Medications, including beta blockers (ie metoprolol) and anabolic steroids can lower HDL. We also see low HDL in the setting of inflammation and acute infection.

Low HDL as a risk factor for heart disease

Multiple population studies have found an inverse relationship between HDL cholesterol and heart disease risk - meaning, low levels of HDL have been associated with an increased risk of heart disease. It appears to be an independent risk factor for heart disease, which means that even after adjusting for other risk factors for heart disease (ie level of LDL cholesterol), the associated risk remains.

In the other direction, elevated levels of HDL cholesterol (particularly if above 60 mg/dL) has been found to be associated with decreased risk of heart disease.

Despite this association, there are several levels of evidence that low HDL cholesterol in and of itself may not actually cause increased risk of heart disease.

1. Low HDL often occurs in the setting of metabolic syndrome, glucose intolerance and type 2 diabetes - sometimes it is seen prior to a formal diagnosis of diabetes by years. In this setting, HDL is low and triglycerides are elevated. LDL cholesterol can be borderline appearing, but the LDL particle concentration typically is elevated (I discuss the difference here). Several studies have shown that after adjusting for LDL particle concentration (not just LDL cholesterol), the risk associated with low HDL decreases significantly

2. Some genetic causes of low HDL are not associated with increased risk of heart disease. Others are.

3. Medications that have been developed to increase HDL cholesterol have not resulted in improved cardiovascular outcomes like decreased risk of heart attack. So it’s not simply enough to just artificially raise HDL cholesterol.

So is my HDL cholesterol important at all?

HDL is a very complex particle with many different sizes and composition. It is thought the heart disease risk associated with HDL cholesterol is much more likely to be related to its functionality (or “efflux capacity”) - essentially its ability to do its job properly.

Research is suggestive that HDL cholesterol efflux capacity is associated with risk for cardiovascular disease. It is not yet available clinically.

So what should I do if I have low HDL cholesterol?

Given there is no solid evidence that increasing HDL cholesterol improves outcomes, major guidelines do not recommend focusing on raising it at this time, particularly not with any medications that are currently available.

Of note, it is included in the 10 year risk calculator your doctor may use in assessing your risk of heart disease, and so depending on your other risk factors, it may indicate a need for more aggressive lowering of your LDL cholesterol.

While we don’t currently recommend medications to raise your HDL cholesterol, there are several overall heart healthy lifestyle factors that can increase HDL cholesterol that you could consider focusing on.

• regular exercise

• maintaining a normal body weight

• smoking cessation

• increased monounsaturated and omega-3 fat intake (subbing out refined grains and trans fat in particular)

That said, until we learn more about HDL functionality, the main focus should be on overall heart healthy lifestyle changes, particularly those that decrease LDL cholesterol.

Interested in working directly with Dr Harkin to optimize your heart health and create a personalized plan?