Cholesterol has a bit of an image problem. The substance flowing throughout our bodies is painted with the brush of a dangerous fat, clogging our arteries and potentially putting us at risk of heart disease and stroke.

However, that’s only half the picture. Yes, cholesterol is a fat-like substance and yes, it can be a problem… but not all the time. In fact, sometimes it’s downright essential.

“Cholesterol plays a crucial role in building cell membranes, and it is important in various hormones and other biological substances that keep us alive,” says Sir Rory Collins, head of the Nuffield Department of Population Health.

“However, the levels of cholesterol that we see, particularly in western populations, are much higher than they should be.”

There’s the problem. Its reputation as a tube-clogging fat rings true when we reach dangerous levels. Blood clots, heart disease and strokes are all associated with too much cholesterol in the body.

According to the World Heart Foundation, high cholesterol is responsible for around 4.4 million deaths a year, and research from 2022 found that the leading risk factor for strokes was caused by high cholesterol levels.

Even more worrying: in many cases, high cholesterol is symptomless – some estimates in recent years have found as many as 39 per cent of people around the world suffer from it, potentially without even knowing.

“Most people don’t have a cholesterol measurement until they’re in their forties or fifties, by which time it’s almost too late,” says Steve Humphries, professor of cardiovascular science at University College London. “Their arteries are already filled up with cholesterol.”

So, what can you do before it’s too late? How should you arm yourself against something that is both incredibly common and hard to notice?

Firstly, if you’re worried, speak to your doctor. Secondly, it helps to better understand how cholesterol actually works. Here are the biggest lessons current science can teach…

Cut the right kind

From the way we talk about cholesterol, it can feel like it’s just a case of reducing it altogether. But it’s actually about achieving a good balance. While issues associated with low levels are possible (links have been found to anxiety, depression and cancer), they are incredibly rare. 

Doctors consider a total cholesterol level of below 5mmol/l – that’s a concentration of 5 millimoles per one litre of blood –  to be healthy. That refers to your total amount of cholesterol, but it’s broken down into two types.

You’ve probably heard your total cholesterol levels can be split into ‘good’ and ‘bad’ – but that’s not entirely accurate.

The important thing to know about cholesterol is that it doesn’t move through your body freely. Instead, it hitches a ride on particles known as lipoproteins. They’re basically specialised delivery trucks that transport cholesterol and other fats through your bloodstream to various destinations in your body.

What determines whether cholesterol is ‘good’ or ‘bad’ isn’t necessarily the cholesterol itself, it’s the role these lipoproteins play. Cholesterol is just the cargo.

There are two main lipoproteins. The first is low-density lipoproteins (LDL). These move cholesterol from the liver, which produces most of your cholesterol, to places all over your body, including your arteries.

This can be useful, but too many LDLs dropping their cholesterol cargo in your arteries can become a key driver of plaque build-up. LDL particles themselves can crash and lodge themselves into your artery walls – the more of them, the likelier this will be. 

High-density lipoproteins (HDL), on the other hand, work in reverse. They’re effectively the refuse trucks, picking up excess cholesterol from your bloodstream, including from the walls of your arteries, and transporting it back to your liver. That’s why HDL cholesterol is known as ‘good’ cholesterol. 

The type of lipoproteins we have matters. We want to keep the low-density low and the high-density high. But how do you actively do that?

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Food is a drug

One of the most common misunderstandings is that most of the cholesterol in your body comes from the food you eat. 

It’s true that some foods, particularly animal products such as meat and dairy, do contain cholesterol. However, most of it is produced by your liver (what’s called ‘blood cholesterol’).

The liver actually makes enough of it to give your body all the nutrients it needs. In fact, only an estimated 20 per cent of your cholesterol is dietary – your body makes the rest. 

What does all this mean in terms of managing your cholesterol levels? Well, first there’s the obvious: keep your dietary cholesterol to a minimum. It is, after all, simply adding to a full plate of cholesterol already in your body. 

“The best way to lower your cholesterol through your diet is by avoiding animal fats – dairy and meat. Other foods contribute to your cholesterol levels, but nowhere near as much,” says Collins.

Secondly, think about the foods that could interfere with your liver function as more like drugs than grub. Even if they’re not adding cholesterol to your body directly, they can do it indirectly, encouraging your liver to produce more cholesterol.

Even worse, more LDL can be made than needed, sending more delivery trucks brimming with cholesterol to your arteries. 

An excess of animal fats, particularly fatty cuts, can create this effect. But one of the biggest culprits here is saturated fats, a cunning villain you’ve probably heard of before. Very sneakily, saturated fats can impair the function of receptors that help the liver keep your overall number of LDLs in check. 

It’s a stealth attack that’s proven deadly around the globe.

“The reason we, in Europe and North America, have high heart disease rates compared to more rural parts of the world is we have far more saturated fats. Back in the 1960s, rural China had almost no heart disease and very minimal cholesterol levels – that was during an era of mostly vegetarian diets,” says Collins. 

Indeed, the mean daily cholesterol intake in Chinese adults increased from 165.8mg per day in 1991 to 266.3mg per day in 2011. That’s a 60 per cent rise in two decades. 

Which foods should we point the finger at? Due to their saturated fat content, foods such as tropical oils (palm or coconut oil), baked goods, sweets and foods that have been fried all contribute to an increase of ‘bad’ cholesterol.

Processed meats – think sausages, bacon and hot dogs – also contain a high amount of saturated fat. According to one review involving 614,000 participants, each additional 50g (1.8oz) serving of processed meat per day is linked to a 42 per cent higher chance of heart disease.

Then there’s sugar. It also acts like a drug on your liver, encouraging it to produce more LDLs and fewer HDLs. A 15-year study found that participants who took in 25 per cent or more of their daily calories in sugar were more than twice as likely to die from heart disease, with cholesterol playing a key role.

So, what’s the solution? Well, if you’re eating lots of it already, scaling back on saturated fats and sugary foods will have the biggest effect. But what you replace them with can be key.

Foods rich in fibre are an excellent substitute. This includes oats and whole grains, nuts, seeds, beans and legumes. 

Replacing your morning bacon sarnie with porridge could significantly help to lower LDL cholesterol in a number of ways. Foods high in soluble fibre (like oats or whole grains) can bind to dietary cholesterol in the small intestine, preventing it from entering your bloodstream. 

Healthy fats, such as those found in salmon and sardines, are high in Omega-3. This has the effect of increasing the size and density of LDL cholesterol particles, making them less likely to stick to artery walls. Omega-3 can also give your liver the signal to produce more HDL. 

Eating these foods can help manage your cholesterol. Although – full disclosure – the impact may be marginal. When it comes to your diet, the key is to focus on bringing down unhealthy fats.

Exercise is critical

The other arm of cholesterol reduction is exercise. Cardio has, for a long time, been a key part of prevention.

Why? As a major review of 39 studies found, aerobic exercise can significantly improve HDL levels. By reducing inflammation, it turns out such workouts can create conditions that encourage the production of your body’s cholesterol clean-up particles.

Equally, recent research has shown that the more active you are, the more saturated fat your muscles use for energy. And this means there is less saturated fat circulating in the body.

“Having that higher HDL level will help to balance out your overall cholesterol, which, along with improving your heart muscle and stopping you from being overweight, helps fend off cholesterol-related health concerns,” says Humphries. 

But it’s not just cardio. Research shows the importance of weight training as well – one 2012 study showed the effectiveness of resistance training in lowering LDL. The more weight you lift, the greater this effect could be.

The pills can work

You might want to sit down for this: in some cases, exercise and a good diet won’t cut it. Other hidden factors could be playing a larger hand in your cholesterol levels. 

First of all: age. As we get older and our liver function declines, our risk of high cholesterol increases. One NHS study found that 72 per cent of UK participants aged between 45 and 64 had high cholesterol. 

In younger groups, males are at a higher risk of high cholesterol levels. In the same blood sample study, women under the age of 45 had a 7 per cent lower risk than men of the same age.

However, this switches to an increased risk for women over the age of 45. In older age, women were 12 per cent more likely than men to have increased cholesterol levels. Studies have linked this increase to menopause where, as oestrogen levels decrease, so do the number of HDL particles.

While diet and exercise can manage cholesterol levels for the majority of people, it becomes harder to manage as we get older or, in some rare cases, when genetic disorders raise our risk. In these cases, drugs might be necessary (ask your doctor if you’re concerned).

The main treatment drug is statins. They work by slowing the body’s cholesterol production process, binding to a specific enzyme in the liver (known as HMG-CoA reductase).

Statins are prescribed when an individual’s risk of heart disease or stroke becomes a danger. Or, more commonly, for anyone who has already had a heart attack or stroke.

While statins, in theory, reduce the amount of cholesterol the body produces, they do have side effects. These can include headaches, dizziness, muscle pains and fatigue.

“Muscle problems, especially in older versions of statins, can occur. Roughly 1 in 10,000 people, typically in the first year of treatment, get this so it is rare,” says Collins. “Because doctors are required to tell people about this risk, there is a tendency for people to attribute muscle pains to the drugs.” 

“We know through placebo trials that most of the time people are reporting muscle pains, it is not caused by the drug. Statins have also been linked to a very minor increase in the chances of diabetes occurring. This is mostly an issue for people right on the cusp, but the risk is small.”

Collins highlights that with cholesterol issues, a personalised approach is best – your needs may differ from others. While there are higher risks with drugs compared to exercise and diets, the benefits vastly outweigh the concerns in serious cases.

But remember, if you have any concerns, best chew the fat with your doctor.

About our experts

Prof Sir Rory Collins is the head of the Nuffield Department of Population Health and professor of medicine and epidemiology at the University of Oxford. He received his knighthood for services to science in 2011. You can find his work published in various journals including Circulation, Lancet Public Health and Heart Protection Study Collaborative Group.

Prof Steve Humphries is an emeritus professor of cardiovascular science at University College London. He has been published in European Journal of Preventive Cardiology, International Journal of Molecular Sciences and Current Opinion in Lipidology, to name a few journals.

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