What’s the fuss about?
A furore has blown up over whether eating saturated fat increases the risk of coronary heart disease after three cardiologists said that “the conceptual model of dietary saturated fat clogging a pipe is just plain wrong”. They also dismissed the drive for foods with lower cholesterol and the use of medications as “misguided”.
The team, who published their report in the British Journal of Sports Medicine, pointed to research that suggests the absence of a link between the consumption of saturated fat and a host of health problems including coronary heart disease, type-2 diabetes and the most common type of stroke.
They also referred to studies they said suggest that reductions in cholesterol are not linked to a lessened risk of death. In addition, they flagged up evidence of health benefits of the so-called “Mediterranean diet”, which has a higher than average fat content.
Did everyone agree?
No. The team’s paper – co-authored by Pascal Meier, a cardiologist at University College London and editor of the journal BMJ Open Heart, Rita Redberg, editor of the journal JAMA Internal Medicine, and Aseem Malhotra, a cardiologist at the NHS Lister hospital in Stevenage – has triggered furious criticism from a range of experts in cardiology and evidence-based medicine.
The commentary drew criticism from a host of experts, from nutritionists to cardiologists. These experts argued that it did not offer any new research but instead drew on “observational” studies of the link between saturated fat intake and coronary heart disease – studies that have “low-quality data and weak conclusions”.
“That is basically looking at people who are given diet questionnaires and following them up. That is always problematic because diet questionnaires can be influenced by having disease,” said Naveed Sattar, professor of metabolic medicine at the University of Glasgow, pointing out that, for example, those known to be at high risk of heart disease are already likely to be on low-fat diets, potentially confounding the results.
David Nunan, from the Centre for Evidence Based Medicine, at the University of Oxford, said there were serious flaws in a study cited in the commentary which had suggested that “bad” cholesterol, known as LDL, was not linked to cardiovascular disease.
He said: “The whole evidence base in nutritional epidemiology is actually difficult because it is hard to do good studies. But the strength of the available evidence to date would still fit more with the consensus that lower LDL cholesterol is better than high for most people.”
Experts also pointed out that the commentary ignored recent high-quality research, including a study published in 2015, which concluded that replacing saturated fats with polyunsaturated fats reduced the risk of cardiovascular events, including coronary heart disease, by 17%, with the reduction linked to a reduction in cholesterol.
“It is clear cut – high cholesterol is bad for you,” said Sattar. He said that people with a genetic predisposition to high cholesterol have a higher risk of heart attacks, while a number of randomised trials have found that medications, such as statins, which lower cholesterol, reduce the risk of cardiovascular disease.
“Millions of people around the world are on statins because they work fantastically well, and that is one of the reasons why heart attack rates have been going down for the last three decades,” he said, adding that blood pressure control and reduced smoking have also contributed significantly to the drop.
Christine Williams, professor of human nutrition at the University of Reading, also voiced concerns about the commentary. “It is unclear what the motivation for publishing these incomplete and limited accounts of the evidence might be at this particular point, since no new research has emerged in the past year or so.”
What did the report suggest we do for a healthy heart?
The authors concluded that “coronary heart disease is a chronic inflammatory disease and it can be reduced effectively by walking 22 minutes a day and eating real food”.
Should we embrace saturated fat and stop fretting about cholesterol?
Not yet. While others agreed that physical activity and a healthy diet are both important in reducing heart disease risk, they said the authors offered no indication of what is meant by “real food”, and maintained that limiting saturated fat and reducing cholesterol are important factors in keeping the heart healthy.
While the Mediterranean diet has received much attention for its apparent health benefits, even the authors of the commentary admitted that the diet is rich in unsaturated, rather than saturated, fats.
“The Mediterranean diet and daily exercise can help reduce heart disease risk, but I’m afraid the claims about saturated fat made in this opinion piece are unhelpful and misleading,” said Mike Knapton, associate medical director at the British Heart Foundation. “When it comes to reducing your risk of heart disease the lower your cholesterol is the better. This can be achieved through a healthy, balanced diet or medication for some.”
Haven’t we been here before?
Yes. It is not the first time that experts have suggested that saturated fat and high cholesterol are not contributors to heart disease – not least a report published last year by the National Obesity Forum and the Public Health Collaboration.
Malhotra, the first author of the new commentary, who is a consultant cardiologist and founding member of the Public Health Collaboration, said at the time: “Eat fat to get slim. Don’t fear fat. Fat is your friend. It’s now truly time to bring back the fat.”
How did that report go down?
Not particularly well. Public Health England’s chief nutritionist, Alison Tedstone, said at the time: “It’s a risk to the nation’s health when potentially influential voices suggest people should eat a high-fat diet, especially saturated fat.”
