Does LDL Cholesterol Cause Heart Disease?
Yes. This isn't a hypothesis, we know this with the same certainty that smoking causes lung cancer.
Four independent lines of evidence prove it:
Genetics: People born with familial hypercholesterolemia have LDL levels of 8-13 mmol/L from birth and develop severe heart disease in their 20s-30s. The only difference is their cholesterol. Conversely, people with genetic variants causing lifelong low LDL have up to 88% lower cardiovascular disease risk. Their brains work fine, hormones are normal—they just don't get heart disease.
Mechanism: We understand how LDL causes disease. Particles infiltrate arterial walls, become oxidized, trigger inflammation, and form plaques. We can watch this happen in imaging studies.
Population studies: Across millions of people worldwide, for every 1.0 mmol/L increase in LDL, there's a 20% increase in cardiovascular disease risk.
Randomized trials: The Cholesterol Treatment Trialists' Collaboration analyzed over 170,000 participants across 26 trials. For every 1.0 mmol/L reduction in LDL, there's a 21% reduction in major cardiovascular events.
What About Those Studies Showing High Cholesterol Helps You Live Longer?
This is where understanding study design matters.
When people develop cancer, their cholesterol drops. When they become frail and lose weight, cholesterol drops. Heart failure, dementia, chronic inflammation—all lower cholesterol before diagnosis.
This is called reverse causality. The cholesterol isn't killing them—they have low cholesterol because they're already sick with something that will kill them.
A study of 4.5 million U.S. veterans excluded everyone who died in the first two years and adjusted for illness and frailty. The inverse relationship between cholesterol and mortality disappeared.
The Swedish centenarian study everyone quotes? The authors published a correction. High cholesterol "neither increases nor decreases the probability of living to 100 years." It's neutral, not protective.
And critically—these are people who survived to 100 despite their cholesterol. For every person with high cholesterol who made it to 100, many others died of heart attacks at 50, 60, and 70. That's survivorship bias.
The Time Factor: Cumulative Exposure
It's not just about your cholesterol level now. It's about lifetime exposure, what we call "cholesterol-years."
The average Canadian has an LDL around 3.2 mmol/L. By age 40, that's significant accumulated exposure. Coronary artery calcium scans show many people who feel perfectly fine already have atherosclerosis by 40.
Even "normal" levels (2.6-3.4 mmol/L) cause atherosclerosis over decades. This is why "I'll worry about my cholesterol when I'm older" is dangerous. Every year you wait, more damage accumulates, and plaques become harder to stabilize.
What About Dementia?
The fear that lowering cholesterol damages your brain is not supported by evidence.
Your brain is 25% cholesterol, but that cholesterol is made in the brain. Blood cholesterol doesn't cross the blood-brain barrier. Blood LDL levels have essentially no direct effect on brain cholesterol.
High cholesterol in midlife (ages 40-60) actually increases dementia risk later by damaging blood vessels feeding your brain.
Decades of statin trials with tens of thousands of patients found no increase in dementia or cognitive problems. A 2025 Korean study of 3.5 million people found LDL under 1.8 mmol/L was associated with 26% lower dementia risk compared to LDL of 2.6-3.3 mmol/L.
Essential Functions: Hormones and Cell Membranes
The argument: cholesterol is essential for testosterone, estrogen, cortisol, vitamin D, and cell membranes. Lower it too much and you'll have problems.
Essential doesn't mean more is better. Your body makes about 1,000 mg of cholesterol daily, more than enough for all essential functions. The excess LDL in your bloodstream isn't being used for these purposes. It's being deposited in arteries.
People with genetic variants causing lifelong LDL of 0.8-1.3 mmol/L have been studied extensively. Their testosterone is normal. Cortisol is normal. Estrogen is normal. Vitamin D production is fine. Cell membranes work perfectly. Brains function normally.
If the body needed high blood cholesterol for these functions, these people would be sick. They're healthier than the rest of us.
Statins and Other Options
About 10-15% report muscle symptoms on statins, but in blinded trials, muscle symptoms occur at nearly identical rates in statin and placebo groups. True statin-induced muscle damage is rare, about 1 in 1,000.
Statins do slightly increase diabetes risk (1 extra case per 1,000 people yearly), but those same 1,000 people have 5-6 fewer major cardiovascular events. The benefit vastly outweighs the risk.
And we're not limited to statins. Ezetimibe, PCSK9 inhibitors (evolocumab, alirocumab, inclisiran), and bempedoic acid all reduce cardiovascular events. If one doesn't work for you, we have options.
Why So Much Confusing Information?
If the evidence is clear, why are people saying otherwise?
Observational studies are easily misinterpreted. The cholesterol paradox in elderly is real data, but concluding high cholesterol is protective ignores reverse causality and survivorship bias.
Cherry-picking is common. The Swedish centenarian study gets quoted constantly. The 4.5 million person veterans study gets ignored.
Credentials can mislead. A PhD doesn't make someone an expert in cardiovascular disease.
Contrarian views get attention. "Everything you've been told about cholesterol is wrong!" gets more clicks than "the scientific consensus is correct."
What You Should Actually Do
Know your numbers: Get your cholesterol checked and track it over time.
Understand your risk: Cholesterol is one piece. Family history, blood pressure, diabetes, smoking, and age all matter. For intermediate risk, a coronary artery calcium scan can be useful.
Lifestyle matters: Mediterranean or plant-based diet, regular exercise (150 minutes weekly), healthy weight, not smoking. These typically lower LDL by 10-15%.
Consider medication if:
• LDL is over 5.0 mmol/L
• You have diabetes (age 40-75)
• Your cardiovascular risk is high
• Family history of early heart disease
• Evidence of atherosclerosis (positive CAC scan)
• Prior heart attack or stroke
Don't wait too long: Remember cumulative exposure. Early intervention prevents more damage than late intervention.
The Bottom Line
LDL cholesterol causes heart disease. Proven through genetics, mechanisms, epidemiology, and randomized trials.
Lowering LDL saves lives—consistently, dramatically, across all populations.
The cholesterol paradox in elderly is largely reverse causality. Sick people have low cholesterol because they're sick.
Your brain, hormones, and essential functions are not harmed by low LDL.
Earlier intervention is better. Cumulative exposure matters.
If you're considering stopping a cholesterol medication because of something online, talk to your doctor first. Bring your concerns. Ask questions. Make decisions together based on your individual situation and the totality of evidence.
Your health is too important to gamble on misinformation.
