A runny nose, a sore throat, a tickly cough: you can spot a cold coming a mile off. Cholesterol, however, isn’t so polite.
You won’t feel it as sticky fat slowly builds up inside your arteries, but over time it raises your risk of heart disease – the world’s deadliest condition, claiming 17.9 million lives a year, or roughly one life every second and a half.
Even more worryingly, many people at risk don’t know it. Recent research suggests that more than 40 per cent of US adults with moderately high cholesterol – and one in four with very high cholesterol – are unaware.
So if you can’t feel it building, how can you tell it’s there?
The reality is, most people can’t – and that’s what makes high cholesterol so dangerous. But knowing what’s really going on beneath the surface might be the key to catching it early.
Hidden in plain sight
Staring at images of sticky plaque clogging an artery, you’d be forgiven for thinking there must be telltale signs – dizziness, a thudding heartbeat, something.
But high cholesterol – raised LDL (low-density lipoprotein) cholesterol, the ‘bad’ type – rarely gives any warning.
“If you have high cholesterol, you’re not going to feel it at all,” says Prof Riyaz Patel, a cardiologist at University College London (UCL) and Barts Health NHS Trust. “It’s a bit like blood pressure. They’re both considered silent killers.
“You will only feel it when it’s too late, if it culminates in a heart attack or stroke.”
High cholesterol can quietly wreak havoc inside your arteries, roughening and narrowing their delicate inner walls. Yet you won’t feel a thing – your blood vessels don’t have pain receptors to warn you when damage is being done.
The real danger is how slowly it happens. There’s no sudden change or sharp pain; cholesterol builds up bit by bit, year after year.
If you can stomach the image, it’s a bit like a bathroom waste pipe gradually clogging with hair and gunk.
At first, you won’t notice when a few strands get caught just beyond the plughole. But over time, as the buildup thickens, the drain starts to slow, until one day it suddenly blocks.
Fortunately, you’ll be pleased to hear, your internal pipes are more sophisticated than bathroom plumbing. Your arteries are flexible and can expand slightly to keep blood flowing, which means even sizeable cholesterol deposits might go unnoticed for years.
With around 100,000km (62,000 miles) of vessels winding through your body – enough to circle the Earth twice – there’s plenty of room for danger to hide.
The problem comes when those fatty clumps harden into plaques. As blood squeezes through the narrowed gaps, pressure rises, and the risk of a serious blockage grows.
Yet in many cases, high cholesterol causes no symptoms at all. Everything seems to be working fine, right up until the moment it isn’t.
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The eyes have it
So far, so worrying. But cholesterol isn’t always hidden. In extreme cases, it can leave visible marks on the body, particularly if you have a genetic condition that could leave you vulnerable to high levels.
Take familial hypercholesterolemia, for instance.
If you’re one of roughly one in 250 people who have inherited the condition, your liver isn’t as effective at clearing LDL (‘bad’) cholesterol from your bloodstream, shooting up your levels two or three times what’s considered healthy.
Mostly, people with familial hypercholesterolemia feel completely normal. But very occasionally, it can manifest in symptoms such as xanthelasma: small, usually harmless and painless, yellowish deposits under the skin.
These fatty deposits form when excess cholesterol seeps into the skin, creating small, waxy bumps that often collect near the eyelids or corners of the eyes.
Eyes can also offer another giveaway: a milky white or grey ring around the iris (the colourful part of your eyes). This ring, called arcus senilis, is made up of cholesterol deposits that build up at the edge of the cornea, the transparent layer that covers the front of the eye.
While it’s common in older adults and often harmless, spotting this ring in younger people can be a warning sign of familial hypercholesterolemia and high cholesterol.
“They would typically be seen at the more extreme ends of high cholesterol levels, as opposed to mildly high cholesterol, which a lot of people have,” Patel says.
Elsewhere in the body, high cholesterol sometimes leaves small physical clues in surprising places: small, fatty lumps called xanthomas. These subtle bumps often form around tendons – usually on the hands, elbows, knees or ankles – and are easy to miss.
So easy, in fact, that you’ve probably missed them when they’ve been staring at you from the world’s most famous painting, the Mona Lisa.
Some researchers believe that Leonardo da Vinci’s muse shows subtle xanthoma lumps on her hands, a possible hint that the world’s most famous smile may have belonged to someone living with high cholesterol.
The same researchers also suggest that the Mona Lisa shows subtle xanthelasma at the inner corner of her left eye.
These signs usually show up in people with familial hypercholesterolemia, but they can sometimes appear in anyone whose cholesterol levels skyrocket when following an extreme diet.
A Florida man in his 40s, following the carnivore diet, learned the risks first-hand.
In 2024, he was admitted to Tampa General Hospital after developing yellowish nodules on his palms, feet, and elbows. Doctors identified them as xanthomas, those fatty deposits caused by exceedingly high cholesterol – so high it was practically seeping through his skin.
This was an extreme case. For months, he had been eating whole sticks of butter, 2–4 kg (6–9lb) of cheese, and burgers loaded with extra fat every single day.
“This patient was not aware that his cholesterol was that high,” Dr Kostas Marmagkiolis, who treated the patient, told US media at the time.
Noting the patient had normal cholesterol levels for years beforehand, Marmagkiolis added: “We have to assume – based on the history of this patient – that those lesions were directly caused by the high cholesterol, which was directly caused by the type of diet that he was [eating].”
All in all, another reason, if you needed one, not to demolish a mountain of cheese for dinner tonight.
Measure to manage
For the majority of us, high cholesterol levels won’t cause yellowish marks or milky rings. There will likely be no symptoms at all. And that’s why Patel stresses the importance of getting your levels checked by a doctor.
“We always say, know your numbers,” he says. “Get your cholesterol checked. If you’re aged 40 or over in the UK, you are eligible for an NHS health check with your doctor.”
In the US, the Centers for Disease Control and Prevention (CDC) advises that healthy adults should get their cholesterol checked every four to six years.
“If you’re over 40, know your cholesterol and blood pressure numbers,” Patel says.
“And if you’re under 40, you should definitely know it if you’ve got any family history, of either very high cholesterol or early heart disease or stroke before the age of 60.”
So, when you get tested, what numbers should you be aiming for?
Ideally, your total cholesterol should be at or below 6 mmol/L (230 mg/dL), and your LDL (the so-called ‘bad’ cholesterol) should stay under 3 mmol/L (115 mg/dL). Staying within these ranges helps keep your arteries clear and your risk of heart disease lower.
But getting your numbers isn’t the finish line – it’s the starting point. They’re a signal to talk with your doctor about how you can fine-tune your diet, exercise, and lifestyle to bring those levels down.
If your results are higher than expected, they could even reveal a genetic condition you didn’t know you had, such as familial hypercholesterolemia. But knowing this can help stop your cholesterol from turning into something far more serious.
You’re not bound by your genes – you just need to know what you’re working with.
As cardiologist Dr Scott Murray puts it: “Genetics may load the gun, but lifestyle pulls the trigger. Don’t sleepwalk into the six-foot trench your DNA dug for you.”
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