Did you spit out your morning brew at the news that the type of coffee you drink can raise your risk of heart disease? According to recent Norwegian research, we should avoid boiled or cafetière coffee because it raises our cholesterol levels more than other kinds, especially filter. But wait. Didn't scientists already decide that coffee was good for us?
You're not alone in being confused. One minute we're told to limit the eggs we eat because yolks are abundant in cholesterol, the next we're free to consume as many as we like. Official health advice states that saturated fat is the main cause of high cholesterol, yet some scientists say this message is oversimplified, or even wrong.
"The public hears mixed messages about cholesterol," agrees Dr Dermot Neely, trustee of national cholesterol charity Heart UK. So, what is the truth about cholesterol and which foods, if any, could drive yours up in ways that might damage your health?
What is cholesterol?
Cholesterol is a fatty substance that travels through the blood on proteins called lipoproteins; some comes from the food we eat, but most (about 80 per cent) is made in the liver. We need some cholesterol to function. It's vital for building cells, for example, producing hormones, and making vitamin D. And there are two key types.
Low-density lipoproteins (LDL) deliver cholesterol to the cells where it's needed. It's referred to as "bad" cholesterol because too much in the body can stick to the lining of arteries, clogging them up and increasing the risk of heart attack and stroke. High-density lipoproteins (HDL), known as the "good" stuff, removes excess cholesterol from blood vessels and tissues and returns it to the liver, where it's flushed away. It also helps protect arteries from inflammation.
Heart UK suggests all adults get their cholesterol checked with a blood test, but there's no single optimum level that everyone should strive for. For many people, higher HDL levels and lower LDL levels are ideal, but cholesterol is only part of the picture when it comes to determining the risk of heart attack or stroke.
Dr Duane Mellor, a registered dietitian and senior lecturer at Aston Medical School, says there are many pieces to the puzzle: the levels of triglycerides (another type of fat) in your blood, your weight, age, diet, medical history and whether you smoke.
Some people have inherited health conditions that mean they're especially susceptible to cholesterol damage. "There's a general increased risk of heart disease if you have high cholesterol," he says, "but it's just part of a picture to be assessed."
The main cause of high cholesterol is saturated fat, according to official health advice. "All fats that we eat can be broken down for use as an energy source, but in general, products of saturated fats that exceed our energy requirements are more easily converted to cholesterol than unsaturated fats," Dr Neely says.
"There is overwhelming evidence that reducing saturated fat, and replacing it with unsaturated fat, can help to reduce risk of heart disease." However, some scientists argue that not all saturated fats are the same. Some research suggests that certain dairy products, such as cheese and yogurt, might actually protect against – not contribute to – heart disease. One theory is that these foods contain types of saturated fats called odd-chain fatty acids that can't be used to make "bad" LDL cholesterol.
"One of the main sources of saturated fat in the British diet is in baked goods – pies, pastries, cakes and biscuits – which have manufactured saturated fats in them," Dr Mellor says. "These are what we need to watch out for because they don't just come with the fats, they come with refined carbohydrates and flour, sugar and salt." Highly processed and quickly absorbed by the body, these foods contain few, if any, nutrients that might limit the damage.
Products many people consider healthy, such as protein/energy bars, can be culprits, too. "Energy-dense foods packed with a lot of sugar and fat, without much fibre, vitamins or minerals, are not going to be a good thing, especially if you're eating them in place of a healthy varied diet," Dr Mellor says. "Energy bars should be seen as 'emergency rations' in exceptional circumstances," adds Dr Neely.
Coconut oil – widely touted as a healthy alternative to butter – should be used sparingly. "It contains twice as much saturated fat as lard and can have a powerful cholesterol raising effect," he says. "It's no healthier than any other saturated fat and should be used sparingly as a flavouring but certainly not as a major energy source."
A lot depends on what you consume with it. Using coconut milk in a curry that contains vegetables and tofu (soy-based products can slightly reduce "bad" cholesterol levels) can be a healthy option.
Being overweight can increase cholesterol, as can lack of sleep. Studies suggest that stress can be a risk factor, too. This might be because we're more likely to eat an unhealthy diet and become overweight when we're under pressure. Another theory is that the body releases certain hormones in response to stress that can boost "bad" cholesterol. But the good news is exercise can help raise "good" HDL and lower "bad" LDL levels.
New research has also shown that women in the menopause could see their "bad" cholesterol rise due to declining oestrogen. HRT can help.
But what about coffee? The latest research shows that substances called diterpenes in coffee have cholesterol-raising properties – but only in high amounts. There's no evidence moderate coffee consumption will increase the risk of heart disease, Dr Mellor says.
"In fact, studies suggest coffee may reduce risk of heart disease and type 2 diabetes." In other words, it's not really the coffee we should be worried about – it's the cakes and biscuits we eat with it.
What to eat and do for a healthy heart
Around 7.6 million people in the UK are living with cardiovascular disease, and heart diseases accounted for one in 10 deaths before the pandemic.
Known risk factors for heart disease include being overweight, high blood pressure, smoking, high cholesterol, diabetes, excessive drinking and inactivity.
Simple fixes such as cutting out cigarettes and alcohol are highly effective, as well as eating a healthy diet.
A healthy diet to reduce the risk of cardiovascular disease means a well-rounded diet with multiple food groups, minimal meat and processed foods, and sparse fatty meals.
"Adopting a whole diet approach to the way we eat – such as the traditional Mediterranean-style diet – together with addressing our lifestyle, which includes not smoking, being physically active and managing our weight, are important to reducing the risk of heart and circulatory conditions," says Victoria Taylor of the British Heart Foundation.
The Mediterranean diet includes large amounts of fruits, vegetables, olive oil, beans and cereal grains such as wheat and rice, some fish, dairy and wine, and limited red meat.