It is a potentially deadly health condition that plagues more than half of all British adults.

High cholesterol causes a sticky form of fat to build up in the arteries, blocking blood flow. Left untreated, it can raise the risk of a heart attack, stroke and even dementia.

And the problem is only growing more common, with an increasing number of young people, aged 30 and under, being diagnosed.

As a result, nearly eight million people in the UK and around 92 million in the US are on statins – a daily tablet which lowers so-called ‘bad’ cholesterol levels.

For many, statins are lifesaving. But the drug is not without side effects, with common ones including muscle pain, digestive issues and headaches.

And, for others, statins are not enough. Half of those taking the pills fail to reach healthy cholesterol levels after two years.

Now experts have told The Mail on Sunday that millions could benefit from a highly effective plant-based diet that could lower cholesterol nearly as much as medication.

The Portfolio diet, coined by Canadian researchers in 2002, focuses on four major food groups which are known to reduce cholesterol: fibre, unsaturated fats, nuts and legumes.

Each has previously been shown to work independently to remove excess cholesterol from the body.

But Dr David Jenkins, the plant-based diet’s creator, who is professor of nutritional sciences at Toronto University, says that, combined, these foods can work similarly to a financial portfolio – taking multiple approaches to maximise returns.

The numbers seem to speak for themselves. Studies show that the Portfolio diet can lower levels of LDL – or ‘bad’ – cholesterol by up to 35 per cent in just one month – roughly the same reduction as some forms of statins provide.

For years, researchers disagreed over the long-term impact of the diet on heart health. But recent research has settled this debate.

A Harvard study, which looked at the diet of nearly 210,000 health professionals in the US over 30 years, found that those who stuck most closely to the Portfolio diet had a 14 per cent lower risk of cardiovascular disease than those who followed it the least closely.

Prof Jenkins says: ‘More and more people have raised cholesterol. But not all of them require a heavy cholesterol reduction – as many of the newer, stronger statins provide. For most people, in fact, a smaller cholesterol reduction – like that provided by the diet – will do. And it benefits anyone trying to eat more healthily, not just those looking to reduce their cholesterol.’

So what is the Portfolio diet and why does it have such a profound effect on cholesterol levels?

Firstly, it’s important to understand the nature of cholesterol. There are several different types of the waxy substance in the body. But the two most important ones are high-density lipoprotein, or HDL, the ‘good’ kind, and low-density lipoprotein, or LDL, the ‘bad’ kind.

LDL can form plaques which block arteries, raising the risk of deadly complications. HDL, meanwhile, is meant to clear LDL 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.

It has long been known that diet can impact this balance, with foods high in saturated fat, such as red meats and dairy products, shown to spike levels of LDL in the blood.

And while some cases of high cholesterol are based on genetics, the most common cause of high LDL cholesterol is poor lifestyle habits. These can include drinking too much alcohol, smoking, not getting enough exercise and eating a diet high in fat.

Certain dietary changes, therefore, have been shown to be particularly effective at reducing cholesterol levels.

Stopping or significantly reducing red meat consumption can lower LDL cholesterol by about 10 per cent, for example. And the renowned Mediterranean diet, which emphasises fruits, vegetables, whole grains, nuts and fish, can typically achieve a 13 per cent reduction over a couple of months.

But some experts now say that none of these dietary changes can rival the cholesterol reduction provided by the Portfolio diet.

Its benefits lie in its combined approach, says Dell Stanford, senior dietician at the British Heart Foundation. She adds: ‘A lot of different foods can lower bad cholesterol, whether that’s oats, beans or certain vegetables. But these tend to only lower it individually by a relatively small amount.

‘The idea behind the Portfolio diet is that combining as many of these individual foods together will result in a large reduction in cholesterol. And studies have shown this, with the bigger reduction occurring for patients who adhere to the diet the most strictly.’

The first food group it focuses on, says Professor Jenkins, is fibre. Or more specifically, a subtype known as viscous fibre.

It is already well known that fibre, a form of carbohydrate, has various health benefits. Studies have shown it can help with weight loss, regulates blood sugar levels and even reduces the risk of bowel cancer. But experts say this specific type of fibre, found in foods such as oats, barley, beans, lentils, aubergines, sweet potatoes, apples and citrus fruits, and seeds such as flax and chia, has particular heart benefits.

This is because it forms a gel in the digestive tract. This sticky substance then binds to cholesterol and bile acids, preventing their absorption into the bloodstream and forcing the body to excrete them as a waste product.

To replace the excreted bile acids, the liver instead takes more cholesterol from the blood, further lowering LDL cholesterol levels.

The second most crucial food group is plant proteins.

Professor Jenkins says: ‘Plant proteins like tofu or tempeh, as well as nuts, seeds and pulses, seem to work by reducing the amount of cholesterol made in the liver.’

As plant-based sources of protein are also low in saturated fat, and tend to be high in fibre, they make for a heart-healthy replacement for animal sources of protein. Unsaturated fats, particularly monounsaturated fats like extra virgin olive oil, have a similar effect, producing much less cholesterol than saturated fats like butter when metabolised in the liver.

A large Spanish trial, published in 2013, found following a healthy Mediterranean-style diet, supplemented with nuts or extra virgin olive oil, significantly reduced the risk of cardiovascular death compared with a low-fat diet.

Other heart-healthy options include canola, soybean or sunflower oils, adds Prof Jenkins.

Finally, a natural compound found in plants, known as sterols, rounds off the Portfolio diet. Structurally similar to cholesterol, plant sterols effectively take its place in order to block its absorption. They exist naturally in nuts, peas and canola oil, which can be used to cook with, but they can also be found in certain enriched foods.

The food firm Benecol, which specialises in cholesterol-lowering food, sells margarine and fruit yogurts which are fortified with plant sterols. ‘Combined, these all work to increase the amount of bad cholesterol excreted by the body as well as reducing its reabsorption back into the body,’ says Professor Jenkins. ‘That’s why the diet is able to have a similar effect to a statin.’

The diet’s benefits don’t stop at cholesterol, however, say experts. A 2023 study by researchers in Canada found that post-menopausal women following the diet had a 31 per cent reduced risk of type 2 diabetes, another significant cardiovascular risk factor for heart disease.

Some people may also find it helpful for weight loss, says nutritionist Rhiannon Lambert.

She has noticed an uptick in client interest in the Portfolio diet in recent years at her London clinic Rhitrition.

‘The diet isn’t designed as a weight-loss plan, but some people might lose weight if they naturally reduce their total energy intake – calories – or increase their intake of high-fibre foods that promote fullness,’ she says. ‘Foods such as oats, beans, vegetables and fruit can help with satisfaction after meals, which may support appetite regulation.’

A sample day of eating, she suggests, could involve soy milk porridge for breakfast, topped with berries and a small handful of nuts. For lunch, try a salad with chickpeas, leafy greens, avocado and sunflower seeds, drizzled with olive oil or, if on-the-go, a wholegrain wrap with hummus, chickpeas, roasted vegetables and salad.

Dinner can be a simple stir-fry, with tofu and mixed vegetables like broccoli, alongside rice. And for pudding, a sterol-fortified yogurt with berries and nuts.

But the diet’s key benefit, Ms Lambert adds, lies in its flexibility.

‘Because the diet’s key components are food groups, rather than specific foods, there is no single right way to follow it.

‘It can be tailored to an individual’s preferences, cultural background, health needs and lifestyle,’ she says.

While meat, technically, is not allowed on the Portfolio diet, it should be all right to eat small amounts of lean protein, such as chicken, as well as fish.

But it is important that people who already take prescribed statins shouldn’t just stop taking them, warns the British Heart Foundation’s Ms Stanford.

‘People already living with cardiovascular disease will need to get their cholesterol levels down much further than the general public, and to get there they will almost certainly require statins,’ she says.

‘This diet is a great addition to reaching that goal, but it shouldn’t replace medication.

‘But if you’re a relatively healthy person trying to keep your cholesterol level down, then this diet is a great way to do that.

‘Bearing in mind that it is estimated that about half of all adults in the UK are living with a cholesterol level higher than it should be, there are lots of people who could benefit from following the Portfolio diet.’