Very high HDL did not protect men; it appeared to harm them.
For generations, medicine held that higher HDL cholesterol meant a safer heart — a reassuring equation that shaped clinical advice and drove pharmaceutical ambition. A large study drawing on nearly half a million UK Biobank participants now complicates that story, finding that men with very high HDL levels face nearly double the risk of cardiovascular and all-cause death, while women with the same elevated levels show no such penalty. The findings suggest that cholesterol, like most things in biology, resists simple arithmetic — and that the meaning of a number depends deeply on the body in which it lives.
- A study of nearly 500,000 people has upended one of medicine's most durable assumptions: that raising HDL cholesterol reliably protects the heart.
- Men with HDL levels above 80 mg per 100 milliliters faced almost twice the mortality risk of those with normal levels — a finding that held even after controlling for smoking, weight, diabetes, and alcohol.
- Women with identically elevated HDL showed no increased risk at all, pointing to profound sex-based differences in how the body processes and deploys lipid particles.
- Very high HDL may signal structurally compromised particles that promote inflammation rather than prevent it, turning a supposed shield into a potential liability.
- The results cast a long shadow over decades of drug development aimed at boosting HDL, helping explain why those therapies have repeatedly failed to improve patient outcomes in clinical trials.
- Clinicians are now confronted with the need to look beyond a single lab number and reckon with the full biological complexity of cardiovascular risk.
For decades, the medical consensus held that HDL — the so-called good cholesterol — was something to maximize. A new study published in the American Journal of Cardiology, drawing on nearly 500,000 participants from the UK Biobank followed for an average of nine years, challenges that assumption in ways that are difficult to dismiss.
Researchers sorted participants into six HDL categories and tracked deaths from cardiovascular causes and all causes. Among men, those with very high HDL levels — above 80 mg per 100 milliliters — faced nearly double the mortality risk compared to men with normal levels. This group made up just 2 percent of male participants, yet their elevated cholesterol offered no protection; it appeared to work against them. Women told a different story entirely. Even though 11 percent of female participants fell into the very high HDL category, they showed no increased mortality risk whatsoever.
The researchers found that very high HDL often corresponds to structurally abnormal particles — malformed in ways that may tip the immune system toward inflammation rather than away from it. HDL particles carry both pro- and anti-inflammatory properties, and in excess, they may do more harm than good, even when standard inflammatory markers like C-reactive protein appear low.
The implications reach well beyond the clinic. If elevated HDL does not reliably protect against cardiovascular death, then the many drugs developed to raise it may have been built on a flawed foundation — a conclusion that aligns with their consistent failure in clinical trials. The study's message is pointed: HDL cholesterol is not a simple proxy for heart health, its meaning shifts with sex and biology, and more is not always better.
For decades, doctors have told patients that higher HDL cholesterol—the so-called good cholesterol—protects the heart. Raise your HDL, the thinking went, and you lower your risk of dying from cardiovascular disease. A new study from the UK Biobank challenges that assumption, at least for men, and the findings are stark enough to reshape how clinicians interpret cholesterol numbers in routine practice.
Researchers publishing in the American Journal of Cardiology examined nearly 500,000 people enrolled in the UK Biobank between 2006 and 2010, all of whom were free from coronary artery disease at the start. Over an average of nine years of follow-up, they tracked deaths from all causes and specifically from cardiovascular events. The team divided participants into six categories based on HDL cholesterol levels, ranging from below 30 mg per 100 milliliters all the way up to above 100 mg per 100 milliliters. The normal range, used as the comparison point, was 40 to 60 mg per 100 milliliters.
The results revealed a troubling pattern in men. Those with very high HDL levels—above 80 mg per 100 milliliters—faced nearly double the risk of dying from cardiovascular causes or any cause compared to men with normal HDL levels. This group represented only 2 percent of the male population in the biobank, but their elevated cholesterol did not protect them; it appeared to harm them. Women, by contrast, showed no such penalty. Even though 11 percent of women in the study had very high HDL levels, they experienced no increased mortality risk when compared to women with normal HDL. The gender difference was striking and consistent.
What makes this finding particularly significant is what it suggests about the nature of HDL itself. The researchers discovered that people with very high HDL levels often had HDL particles that were structurally compromised—malformed in ways that altered how they functioned in the body. HDL particles have both pro-inflammatory and anti-inflammatory properties, meaning they influence the immune system directly. Very high levels of these particles, even if they appear protective on paper, may actually trigger elevated systemic inflammation that increases death risk. The study noted that C-reactive protein, a marker of inflammation, was actually lower in the highest HDL group, likely because these individuals had fewer traditional cardiovascular risk factors to begin with—they tended to be women with lower body weight and lower triglycerides, without diabetes or high blood pressure.
The findings raise uncomfortable questions about decades of clinical practice and pharmaceutical development. If raising HDL cholesterol does not reliably protect against cardiovascular death, then the numerous drugs developed specifically to boost HDL levels may have been built on a flawed premise. The authors note that their results help explain why interventions targeting HDL increase have largely failed to improve outcomes in clinical trials. HDL cholesterol, it turns out, is not a simple marker of heart health. The relationship between the amount of HDL in the blood and actual cardiovascular protection is far more complex, and it appears to operate differently depending on sex.
The study controlled for multiple confounding factors—alcohol consumption, smoking, weight, blood pressure, diabetes status—and the association between very high HDL and increased mortality risk in men persisted. Even when the researchers accounted for genetic variants known to influence HDL levels, the pattern held. This suggests the risk is real and not merely an artifact of measurement or statistical error. The implication for clinical practice is sobering: HDL cholesterol levels should no longer be treated as a straightforward indicator of cardiovascular risk in the general population, particularly in men. Doctors will need to look beyond the number on a lab report and consider the full picture of a patient's health, the structure and function of their HDL particles, and the emerging evidence that more is not always better.
Citas Notables
Very high HDL-C levels are markers of high risk in men alone, and high HDL-C levels are not deemed a reliable marker of heart protection in current clinical practice.— Study authors, American Journal of Cardiology
La Conversación del Hearth Otra perspectiva de la historia
So the study found that very high HDL is actually risky for men. But HDL has been called good cholesterol for so long—how did we get this so wrong?
We didn't get it entirely wrong, but we oversimplified it. The genetic variants that raise HDL do seem to protect against heart disease in many people. The problem is that very high levels—above 80—appear to be a different phenomenon. The particles themselves become dysfunctional.
Dysfunctional how?
They lose their normal structure. HDL particles are supposed to have anti-inflammatory effects, but when there are too many of them, or when they're malformed, they can actually trigger inflammation in the body. It's like having too much of something that's normally helpful.
And this only happens in men?
That's what the data shows. Women have naturally higher HDL levels than men, and their bodies seem to handle very high levels without the same mortality penalty. There's something about female physiology—possibly hormonal, possibly genetic—that protects them from this risk.
Does this mean all those HDL-raising drugs were a waste?
It helps explain why they haven't worked as well as hoped. If the problem isn't simply the amount of HDL but its quality and function, then just raising the number won't help. You might even make things worse.
What should doctors do differently now?
They need to stop treating HDL as a simple good-versus-bad marker. A high number doesn't automatically mean lower risk, especially in men. The full clinical picture matters—weight, inflammation markers, other lipids. The number alone is no longer reliable.