Saturated fat may be less harmful than previously thought
A heart specialist has challenged current advice on how much saturated fat and cholesterol we should eat, based on his reading of the evidence around fat, cholesterol, and heart disease.
BMJ Group News
What do we know already?
Most people are familiar with the advice that eating a low-fat diet helps to reduce cholesterol and that lower cholesterol reduces the chances of getting heart disease.
Cardiologist Dr Aseem Malhotra says most of this advice was based on a study from 1970 which suggested that risk of heart disease was greater for people with high cholesterol. So the advice was simple: eat less cholesterol. The biggest culprit was seen to be saturated fat, which is high in cholesterol, and is found in red meat, eggs, and dairy products.
Saturated fat also contains a lot of calories, so it was assumed that it was fattening as well as bad for your heart. Eat less saturated fat, the advice said, and we’ll have healthier hearts and leaner figures.
Research since the 1970s has shown that things are not as straightforward as was first thought. Dr Malhotra says that it may be time to revisit current advice.
What does the new study say?
The main points of the review article are:
- Cholesterol is complicated. Many of us are now familiar with the idea of ‘good’ (high-density lipoprotein, or HDL) and ‘bad’ (low-density lipoprotein, or LDL) cholesterol. But it seems that it’s even more complex than that. According to the article, recent studies have found that only one type of LDL cholesterol causes heart disease, and that’s not a type you can lower through eating less saturated fat.
- Diets low in saturated fat can make us fatter and less healthy. This is because fat contains a lot of the flavour of food. To improve the flavour of low-fat foods, manufacturers often add sugar, so that many foods labelled ‘low-fat’ are packed with sugar. There is mounting evidence that a high-sugar diet may lead to what’s called the ‘ metabolic syndrome’. This is an unhealthy combination of weight gain, high blood pressure, and reduced ‘good’ cholesterol.
- Some people may be taking medicines they don’t need. Because of the concern over high cholesterol, millions of people in the UK take statins to try to lower their cholesterol or stop them having further heart problems if they already have heart disease. There is good evidence that people who are at high risk of heart problems benefit from taking statins. But the article questions whether everyone prescribed a statin to lower cholesterol really needs it.
- Like cholesterol, calories are complicated. The body processes different types of foods in different ways. Just because saturated fat contains a lot of calories doesn’t mean it makes us gain weight more than foods with fewer calories.
Dr Malhotra is careful to point out the difference between the saturated fat found in unprocessed meat and dairy products and the harmful ‘trans fats’ found in fast food, margarine, and some bakery products. Trans fats cause heart disease by causing inflammation ( swelling) in blood vessels and other tissues in the body.