HDL is high-density lipoprotein, the smallest and densest class of particle that carries fat and cholesterol through the blood; on a lipid panel, “HDL cholesterol” is the amount of cholesterol those particles are carrying. HDL collects cholesterol from tissues, including the artery wall, and returns it to the liver for disposal, which is how it earned the nickname “good” cholesterol. That nickname has aged badly: a low HDL level is still a reliable warning sign, but raising the number with drugs has not produced the benefit the label implies. The partner reference entry HDL — high-density lipoprotein sets out the normal ranges for men and women and what a low result means.
What it measures
The value comes from a venous blood draw, reported as HDL cholesterol (HDL-C) in mg/dL in the United States and in mmol/L in most other countries. The lab does not count particles. It blocks or removes the apolipoprotein B lipoproteins and measures the cholesterol left behind, nearly all of which sits inside HDL. Fasting is not required for an accurate HDL result, though it still matters for triglycerides and a calculated LDL on the same panel.
Two things the test does not tell you: how many HDL particles you carry, and how well they work, since the capacity to pull cholesterol out of artery-wall macrophages varies between people with identical HDL-C. The number is also subtracted from total cholesterol to give non-HDL cholesterol, a stand-in for the atherogenic particles counted as LDL (LDL, “bad” cholesterol) plus remnant lipoproteins.
Typical values
US lipid panels usually flag HDL cholesterol against sex-specific bands:
| Band | mg/dL | mmol/L (approx.) |
|---|---|---|
| Low, men | Below 40 | Below about 1.0 |
| Low, women | Below 50 | Below about 1.3 |
| Once labeled protective | 60 and above | About 1.55 and above |
Treat these as labels rather than targets. Reference intervals differ by lab and assay, women run higher than men across the whole distribution, and the old rule that 60 mg/dL and above counts as a protective factor is no longer built into current risk calculators, which take HDL as one continuous input.
Why it matters for longevity
In large observational cohorts, lower HDL cholesterol is associated with more coronary heart disease, more stroke and higher all-cause mortality, and the association survives adjustment for the usual risk factors. Low HDL is also one of the five components of metabolic syndrome, alongside waist circumference, blood pressure, fasting glucose and Triglycerides.
Causality is a different question. Genetic studies of variants that raise HDL cholesterol have generally not found the lower heart-disease risk the observational data predicts, and drugs that raise it, including niacin added to a statin and the CETP inhibitors, lifted the number in trials without reducing cardiovascular events. Several cohorts also describe a U-shaped curve, with unusually high HDL cholesterol tracking higher mortality rather than lower.
The practical reading: low HDL is most useful as a marker of what surrounds it, such as insulin resistance, excess visceral fat, inactivity, smoking and high triglycerides, rather than as a target to raise on its own.
What changes it
Regular aerobic exercise raises HDL cholesterol modestly, with the effect tied more to weekly volume than to intensity. Losing excess weight, quitting smoking, and replacing refined carbohydrate and trans fat with unsaturated fat from olive oil, nuts and fish move it in the same direction, usually as triglycerides fall. Alcohol raises HDL cholesterol too, which is not a reason to drink: the harm elsewhere outweighs that one lipid effect.
Part of your level is not yours to set. Common gene variants explain much of the spread between healthy people, and rare ones can produce very low or very high values on their own. Anabolic steroids lower HDL sharply. Statins raise it slightly and fibrates raise it more, but those drugs are prescribed for their effect on LDL and triglycerides; on current evidence, HDL itself is not a target worth medicating.
Related reading
- Heart Health: A Prevention Guide for Longevity
- Which Blood Tests Reflect Aging and How to Read Them
- How to Improve Metabolic Health: A Practical Guide
- Cholesterol (total)
Disclaimer. This article is for information only and does not replace medical advice. Talk to a qualified clinician before changing anything about your health.