HDL cholesterol is a type of cholesterol carried through your blood by high-density lipoproteins, small protein-fat packages that pick up excess cholesterol from your tissues and ferry it back to your liver for disposal. It’s often called “good” cholesterol because this cleanup process helps keep cholesterol from building up inside artery walls. For most adults, a level of 60 mg/dL or higher is considered ideal, while levels below 40 mg/dL in men or below 50 mg/dL in women are considered low.
How HDL Protects Your Arteries
When cholesterol accumulates in artery walls, immune cells swallow it and become bloated “foam cells,” forming the fatty plaques that narrow arteries and set the stage for heart attacks. HDL particles work against this process through what scientists call reverse cholesterol transport. HDL docks with these foam cells and pulls free cholesterol out of them, essentially vacuuming plaque-building material from artery walls.
Once HDL picks up that cholesterol, an enzyme converts it into a more compact form so the particle can carry more of it. The loaded HDL then delivers its cargo to the liver in one of two ways: it can bind directly to a receptor on liver cells, or it can hand off its cholesterol to other particles that the liver clears separately. Either way, the cholesterol ends up in the liver, where it’s converted into bile acids or excreted directly into bile and eventually leaves your body through digestion. This recycling loop is what gives HDL its protective reputation.
What Your HDL Number Means
HDL shows up on a standard lipid panel, the blood test your doctor orders to check cholesterol. The results are reported in milligrams per deciliter (mg/dL). Here’s how the numbers break down for adults 20 and older:
- Low: Below 40 mg/dL for men, below 50 mg/dL for women
- Acceptable: 40 to 59 mg/dL
- Optimal: 60 mg/dL or higher
Your HDL number also factors into your non-HDL cholesterol calculation, which is simply your total cholesterol minus your HDL. Non-HDL cholesterol captures all the potentially harmful cholesterol types in a single number and is increasingly used in cardiovascular risk assessments. A higher HDL brings that non-HDL number down, which is one reason clinicians pay attention to it.
Very High HDL May Not Be Better
For decades, the assumption was simple: higher HDL means lower risk. Recent research complicates that picture considerably. A U-shaped pattern has emerged in large population studies, meaning both very low and very high HDL levels are linked to worse outcomes.
Data from the UK and Emory Cardiovascular Biobank found that people with HDL above 80 mg/dL had roughly double the risk of death from any cause and a 71% higher risk of cardiovascular death compared to people in the 40 to 60 mg/dL range. A Danish study of more than 100,000 people from the Copenhagen City Heart Study and the Copenhagen General Population Study confirmed this U-shaped curve. Researchers from the Multi-Ethnic Study of Atherosclerosis also found that people with HDL at 60 mg/dL or above showed signs of increased scarring in heart muscle tissue compared to those with normal levels.
The reasons behind this aren’t fully understood, but the takeaway is practical: an extremely high HDL reading isn’t automatically a sign of good health, and it may warrant a closer look from your doctor rather than a pat on the back.
HDL and Heart Disease Risk Varies by Race
Another layer of nuance comes from a 2022 study highlighted by the National Heart, Lung, and Blood Institute. Researchers found that low HDL predicted increased risk of heart attacks in white adults, consistent with decades of prior research, but the same association did not hold for Black adults. Higher HDL levels were not protective for either group. This was the first major study to show that HDL’s predictive value for heart disease is not universal across racial groups, raising questions about how much weight to place on any single cholesterol number in isolation.
Genetics Play a Major Role
Your HDL level is 40 to 60% inherited. That means for many people, lifestyle choices alone won’t fully explain a low or high reading. The genetic picture is complex, typically involving dozens of genes interacting with each other and with environmental factors like diet, exercise, and smoking.
In rare cases, a single gene mutation can dramatically shift HDL levels. Mutations in the ABCA1 gene cause Tangier disease, which drops HDL below 5 mg/dL. On the other end, mutations in the gene for a protein called CETP can push HDL above 120 mg/dL. These are extreme examples, but they illustrate how powerfully genetics can override everything else. Even factors that seem purely environmental, like alcohol consumption or smoking habits, have their own genetic contributors that indirectly shape your HDL.
Why Raising HDL With Drugs Hasn’t Worked
Given HDL’s reputation as “good” cholesterol, pharmaceutical companies invested heavily in drugs designed to raise it. Several classes of medications, including cholesterol transfer protein inhibitors, fibrates, and niacin, can successfully increase HDL numbers on a blood test. The problem: large clinical trials consistently showed that raising HDL through medication did not reduce heart attacks, strokes, or cardiovascular deaths.
This disconnect suggests that the number on your lab report may not capture what actually matters. HDL’s protective function, its ability to pull cholesterol from artery walls, varies from person to person. Two people with identical HDL levels can have particles that function very differently. Current research is shifting toward measuring HDL function rather than just HDL quantity, though that kind of testing isn’t part of routine clinical practice yet.
Lifestyle Changes That Raise HDL
While medications have disappointed, lifestyle changes remain the most reliable way to improve both your HDL level and, likely, HDL function. The most effective strategies are straightforward.
Regular aerobic exercise is the single most consistent HDL booster. Aim for 30 minutes of moderate to vigorous activity on most days. Running, cycling, swimming, and brisk walking all count. Losing excess weight, particularly fat stored around your waist, also raises HDL. Quitting smoking helps too, since both direct smoking and secondhand smoke exposure lower HDL.
Diet matters, but in a specific way: replacing the types of fat you eat has more impact than simply cutting fat. Limiting saturated fats from full-fat dairy, high-fat meats, butter, and lard while eating more unsaturated fats from olive oil, avocados, and nuts tends to improve HDL. Trans fats, found in some processed and fried foods, are particularly harmful to HDL levels. Cutting back on sugar and refined carbohydrates while eating more fiber from oatmeal, beans, and whole grains rounds out the dietary picture. Moderate alcohol intake may have a small positive effect on HDL, though the evidence isn’t strong enough to recommend drinking for that purpose, and excess alcohol causes weight gain that lowers HDL.