Why it ISN’T fat that clogs up your arteries

The true villain may surprise you!

What causes heart disease? A simple enough question, and one you might have thought was settled years ago. But the answer has become the subject of much debate – with implications for many of us on how we lead our lives and the medication we take.

For years the finger of blame has pointed at cholesterol, a fatty substance produced by the liver.

While some cholesterol is vital (it helps produce hormones and vitamin D, for instance), the consensus has been that too much – or rather, too much of the low density lipoproteins that transport cholesterol in the bloodstream – damages the blood vessels. This leads to a risk of blood clots, heart attacks and stroke.

This thinking was confirmed in 2004 by the influential Interheart study reported in the Lancet, which showed that 45% of deaths from heart disease were caused by high cholesterol – making it the biggest modifiable cause, along with smoking, and outstripping causes such as high blood pressure and obesity.

The message on cholesterol has been twofold: avoid foods rich in cholesterol-raising saturated fat such as butter, cream and cheese, and if you’re at risk of heart disease, take cholesterol-busting statins.

Cutting cholesterol has been a success, according to Professor Peter Weissberg, medical director of the British Heart Foundation, who says better diet – plus a drop in tobacco use – halved death rates from heart disease between 1961 and 2011.

‘In the early Sixties, consumption of foods high in saturated fat such as butter, whole milk and red meat were the norm – and have largely been replaced by low-fat spreads, vegetable oils, skimmed milk and white meat,’ he says.

Yet today there are holes in this ‘cholesterol hypothesis’ – with a number of specialists insisting the traditional heart health message is over-simplistic.

The relationship is not as black and white as we thought, says Dr Rajiv Chowdhury, a cardiovascular epidemiologist. He led a major review of 72 studies that suggested saturated fat doesn’t cause heart disease.

‘While earlier studies showed saturated fat does raise bad cholesterol, the bigger picture shows it also increases potentially good cholesterol, which reduces bad fats in blood,’ he says. The findings were controversial, but Dr Chowdhury is one of an increasing number of scientists who believe current advice is misguided, if not harmful.

‘The mantra that saturated fat must be removed to reduce the risk of cardiovascular disease has dominated dietary advice for decades,’ says Dr Aseem Malhotra, cardiologist and medical adviser to the Academy of Medical Royal Colleges.

‘Yet the scientific evidence shows this advice has increased our cardiovascular risks.’

Saturated fat has various subtypes that vary widely in their health effects, says Dr Chowdhury. ‘Without considering these, it’s got to be harmful to replace all saturated fats with sugar or refined carbohydrates, as food manufacturers have been doing in the interests of heart health.’

The second line of attack is statins, which have been shown to reduce cholesterol even in healthy people, and prevent heart attacks in those with risk factors. Though they were originally targeted at people with a 30% risk of a heart attack in the next 10 years, guidelines have been changed, lowering the threshold.

Now anyone with a 10% risk of developing cardiovascular disease in the next 10 years should be offered a statin, says the UK’s National Institute for Health and Care Excellence. It says if everyone at risk took a statin, 8,000 lives could be saved.

Among those prescribed statins are those who have survived a heart attack, or have severe chest pain, as well as those at risk because of high blood pressure, high cholesterol, obesity, smoking or diabetes.

‘To make progress in the battle against heart disease, we must encourage exercise, improve our diets still further, stop smoking and where appropriate offer statins,’ says NICE’s Professor Mark Baker.

‘The overwhelming body of evi- dence supports the use of statins even in people at low risk.’

Yet the evidence is not conclusive. One particularly difficult piece of research to explain, published in the American Heart journal in 2009, showed 75% of patients admitted to hospital with a heart attack had cholesterol levels within the safe range; 50% had optimal levels of cholesterol.

Furthermore, your cholesterol falls naturally with age, particularly in older people with chronic health problems. And it may be unhealthy to have low levels. A study published in the Lancet in 2001 showed long-term low cholesterol increases the risk of premature death – ‘and the earlier that patients start to have lower cholesterol, the greater the risk’.

‘Cholesterol is still being demonised,’ says Dr Malcolm Kendrick, author of The Great Cholesterol Con. ‘When I tell people the higher their cholesterol level the longer they will live, they look at me as if my medication is not working.’

So, if cholesterol’s role is overplayed, what does cause heart disease?

One emerging theory is sugar, which is thought to promote inflammation inside the arteries. A study in the Journal of the American Medical Association

found adults who have three sugary drinks a day had triple the chance of a heart attack. One theory is that sugar encourages a particular type of ‘bad’ cholesterol that causes inflammation.

There are at least five types of LDL, the low-density lipoprotein that transports cholesterol around the body.

The healthiest is ‘large and fluffy,’ says Dr Chowdhury. It’s the smallest, most dense forms that are most dangerous because they can penetrate artery walls, setting off inflammation.

‘And these smaller, artery-clogging particles are increased not by saturated fat but by sugary foods,’ he says.

As Dr Michael Rothberg, vice president at the Medicine Institute in Cleveland, says: ‘The familiar image of coronary arteries as kitchen pipes clogged with fat is simple but wrong.’ He adds that the overwhelming evidence was that ‘most’ heart attacks occur to people whose arteries have only mild cholesterol plaques.

‘We now know coronary artery disease is an inflammatory disease in which cholesterol from the blood is deposited in artery walls and causes an inflammatory reaction like a pimple,’ he says. ‘It’s when these pimples pop that the blood in the arteries can clot. If the clot closes the artery, that causes a heart attack.’

Experts acknowledge that the theory that inflammation is caused by sugar needs investigation.

‘So far the concerns about sugar largely relate to obesity and diabetes,’ says Professor Susan Jebb of Nuffield Department of Primary Care Health Sciences. ‘But it’s probably true chronic inflammation is one reason that obesity and some dietary components such as sugar lead to an increased risk of heart disease.’

Simon Capewell, of the University of Liverpool, is also concerned the potential risk of sugar is not being highlighted. ‘The research shows adults who regularly consume sugary drinks increase their risk of heart disease and have an increased risk of dying from a heart attack,’ he says.

‘I’m sure part of that increased risk is that the extra sugar leads to raised blood pressure and part of that is by increasing arterial inflammation.’

Some researchers say statins may protect against heart disease by reducing this inflammation. So, how do we cut our risk of heart disease? The message should be about reducing inflammation, says Dr Aseem Malhotra, a cardiologist at Croydon University Hospital: ‘Anything that can be done to reduce this, whether it’s changing your lifestyle – switching to a Mediterranean diet, stopping smoking, exercising, reducing stress and taking medication including perhaps statins – will be helpful.’