For decades, doctors believed high cholesterol was a clear warning sign of an impending heart attack and early death. 

Medical experts have long warned patients to not eat too much red meat, cheese and eggs, believing cholesterol in food raises cholesterol in the body, and that those high levels then cause a myriad of harmful health problems.

Cholesterol is a waxy substance that builds cells, synthesizes vitamins and produces hormones like estrogen and testosterone. There are two types: HDL – the ‘good’ kind – and LDL – the ‘bad’ kind. 

LDL can form plaques that buildup and block arteries, raising the risk of heart disease, heart attack and stroke. HDL is meant to clear that by moving it from the bloodstream to the liver where it gets filtered out of the body. When HDL levels fall too low, LDL can build up unchecked.

But scientists are now discovering the real danger isn’t indulging in cholesterol-high foods and increasing LDL levels – a medical myth that has led to billions of dollars in pharmaceutical and fad diet sales across decades – it’s actually when HDL levels fall too low.

The idea that high cholesterol alone could drive up the risk of heart disease took off in the 1950s and was considered medical orthodoxy until recently, as more scientists have come to realize that Americans were fed a half-truth for decades.

As it persisted, the diet industry continued to flourish. It helped spawn the $8.4 billion diet food market, produced multiple generations of cardiologists advising against cholesterol-rich foods and fueled a $47 billion drug market. 

But now, researchers are challenging that long-held belief, arguing cholesterol levels aren’t the medical ‘check engine light’ they’ve long been made out to be and there are other ways to protect yourself that don’t include skipping a steak dinner and taking a pill every day.

 For years, doctors have viewed high LDL cholesterol as a clear indicator of heart attack risk, often reacting urgently to extremely elevated levels. But some people with cholesterol levels between 200 and 500 mg/dL show no signs of artery clogging—so long as they are lean and healthy

Around 30 million Americans have high cholesterol and 128 million have heart disease. 

High LDL cholesterol has been linked to a 20 to 30 percent higher risk a death due to heart disease.

And one in six Americans takes a statin – a class of cholesterol medications – to lower LDL, but millions may not actually need one. 

LDL cholesterol has been vilified as ‘bad’ cholesterol for decades as multiple large-scale investigations showed links between high levels of the sticky substance and heart disease. 

In the 1960s, the famous Framingham Heart Study revealed higher total cholesterol levels were associated with a significantly increased risk of developing coronary heart disease (CHD), which includes heart attacks.

However, early research made no distinction between large, buoyant LDL particles that move through the body without building up and forming plaques and the dense pellet-like LDL particles that more easily stick to artery walls.

And so the idea that cholesterol is a cause of heart disease dominated mainstream medicine for decades.

But researchers are beginning to understand that the medical field has drastically oversimplified cholesterol and its role in the body. 

The graph shows no link between LDL and plaque growth over one year in healthy people on the keto diet who were fit but started out with high LDL cholesterol

Dr Nick Norwitz, a specialist in metabolic disorder research, had been seeing a patient in her 60s for over 10 years who had dangerously high levels of ‘bad’ LDL cholesterol. 

Her results were so high, in fact, that when doctors see numbers at those levels, they typically believe the lab made a mistake. 

However, his patient’s tests weren’t wrong. 

But what shocked Dr Norwitz was that despite her ‘astronomical’ cholesterol, ‘she has no plaque whatsoever in her arteries,’ and was healthy overall, he told DailyMail.com. 

Dr Nick Norwitz is challenging the assumption that high cholesterol is a reliable warning sign for heart attack risk

His patient was defying the laws of traditional medicine. 

Now, Dr Norwitz has co-authored a study on very high cholesterol levels in healthy and fit adults.

These people followed a strict low-carb and high-fat keto diet, a diet doctors approach with caution over fears of increasing cholesterol.

But researchers found no evidence of worsening artery plaque, a key indicator of heart disease risk. 

Dr Norwitz has found extremely high cholesterol alone might not be as influential in driving heart disease as scientists have long thought.

Some people with shockingly high cholesterol that would prompt quick action from a doctor showed zero artery clogging over time. 

But there was a caveat: these people were lean, healthy, and followers of the keto diet, a meal plan much loved in the corner of the wellness field that centers on boosting testosterone. 

They had perfect blood sugar, sky-high ‘good’ HDL cholesterol, and virtually no inflammation. Instead of being a heart attack warning sign, soaring LDL was a harmless byproduct of their body burning fat for fuel. 

High cholesterol is still risky for people with obesity, diabetes, or insulin resistance, as well as people with certain genetic disorders

The cholesterol myth helped fuel a flourishing $20 billion market of statin drugs that lower blood cholesterol by blocking an enzyme in the liver that produces it and increasing the number of LDL receptors on cells

Dr Norwitz’s research found that, unlike people with genetic cholesterol disorders —where faulty metabolism leads to dangerous arterial clogging — these keto dieters with high LDL cholesterol were metabolically pristine, without signs of obesity, diabetes, or insulin resistance.

The 100 dieters in Dr Norwitz’s study showed their liver was producing large, buoyant LDL particles that were less likely to stick to artery walls than the typical waxy cholesterol that forms dangerous plaques. 

The participants also had fully functioning LDL receptors and didn’t need to be put on a statin. 

The study concluded not all LDL cholesterol is equal and is not a standalone predictor of heart disease. 

In the absence of blaming LDL for heart disease, other contributors could be genetics, smoking, inactivity, high blood pressure, obesity and diabetes. 

Dr Norwitz told DailyMail.com: ‘We focus in medicine a lot on biomarkers we can act upon, that we have drugs for, rather than things like overall metabolic health. So, for better or worse, LDL cholesterol has been the focus, and there’s just a big assumption built in that it alone is sufficient to drive cardiovascular risk.

‘But we’ve never had a human population where they only have high LDL, they’re metabolically healthy, and they don’t have an underlying genetic cause.’ 

He added: ‘One paper can’t overturn [this prevailing idea], but it exposes a major blind spot and the prevailing model because if you can have a population of patients with cholesterol this high who, as a population, aren’t at very high risk for heart disease, it means there’s something we’re missing.’