Love your heart!

Dr Nikki Stamp gives us the lowdown on cholesterol and its effects on our heart health

Cholesterol is inevitably mentioned when we discuss heart health. Your doctor might order a cholesterol test as part of a regular health check and you will need to address your cholesterol if it is found to be ‘too high’.

Cholesterol is a vital part of our bodies. It’s a type of lipid or fat molecule that is an important component in the tiny walls that make up all of our cells. Our bodies also need cholesterol to make bile (the green liquid our gall bladder stores that helps our gut deal with fats we eat) and to make vitamin D. Our bodies can make cholesterol, mainly in the liver. We also get it from our diet, predominantly from animal sources like meat, egg yolks, milk and cheese.

The fact that cholesterol is vital for life does not mean it is always healthy: you can have too much of a good thing.

Good vs bad

When we talk about ‘cholesterol’ generically, we’re usually talking about three separate molecules. Cholesterol is like a group of cousins, including high-density lipoprotein (HDL) and low-density lipoprotein (LDL), and all are involved in forming plaque inside our arteries. LDL is sometimes called ‘bad cholesterol’. It circulates around the body, away from places it can be excreted, like the liver, but close to places where it can cause mischief, namely in the blood vessels.

When a blood vessel is injured (from age, smoking, diabetes or our genes) these bad cholesterol molecules rush to the scene and invade the blood vessel wall, making it swell. Our bodies then call in other cells like platelets, muscle cells and immune cells to try to help, but they only make plaque that can block the artery. This is called atherosclerosis, which means ‘fatty scar’. It’s what is responsible for heart attacks and strokes.

HDL is sometimes called ‘good cholesterol’. The reason HDL is good for us is that it basically does the opposite of LDL by pulling together the bad cholesterols from around the body (including plaque in our arteries). They’re sent to the liver where they’re turned into bile, stored in the gall bladder and then pushed into the bowel where, well, they are gotten rid of in our poo.

Scientific studies show a very strong link between higher cholesterol levels and heart disease. At the same time, other clinical trials give slightly different findings – that cholesterol and LDL in the blood may reduce the risk of heart disease. Despite the differences, most trials that look at the benefit of lowering cholesterol and LDL show that heart attacks are reduced by somewhere between 19 and 34 per cent, which by medical standards is a big drop after treating just one risk factor.

The association of cholesterol with heart disease has come under intense scrutiny in recent times, with vocal opponents stating that we have been misled. They say it’s not cholesterol that causes blockages in our arteries but sugar, inflammation or other culprits. Scientific evidence on cholesterol is not perfect, but it is strong enough to confirm that it has a role. I agree that a number of other factors are at play, such as sugar and hormonal patterns. But to let cholesterol off the hook based on the current evidence seems premature.

Facing the fats

Scientific evidence has found that not all fats are created equal. And this has profound implications for the way we view fats and their impact on heart disease. Saturated fats are found in animal meats and dairy, plant oils like coconut oil and palm oil, and most commercially made foods like cakes or doughnuts. Trans fatty acids (sometimes called trans fats) occur in beef, lamb and dairy, and in a chemical change in vegetable oils called partial hydrogenation. Partially hydrogenated vegetable oils are produced in factories to make oil-based products more spreadable. Polyunsaturated fatty acids, such as linoleic acid and those found in fish, are long chains of fatty acids that have a vital role in the production of a number of hormones in our bodies. Monounsaturated fatty acids are those found in nuts and olive oil.

The classification is important, not just because these molecules look alike but because their effects on our health can be similar. Saturated fats, for example, originally received most of the blame for causing heart disease by raising bad cholesterol levels. It may not be as cut and dried as we once thought, though: the link between saturated fats and heart disease has since been questioned.

Despite this, a recent large study by the American Heart Association confirmed the link, but also recommended replacing saturated fat with polyunsaturated fat. What we replace saturated fat with in our diets may also be worse for us than the saturated fat itself. There is more investigation to be done on fats, and I’m sure we will see further debate.

The two unsaturated fat groups, polyunsaturated and monounsaturated fats, are often called ‘good fats’. However, unsaturated fats may be incredibly useful at directly fighting some of the processes that result in heart disease. Foods containing these types of fats can increase HDL cholesterol, reduce inflammation, improve the way our bodies handle sugar and insulin, and help blood flow smoothly through our blood vessels.

The last group, trans fats, is likely to be where problems arise. Trans fats don’t just increase our risk of heart disease, they also impede our body’s ability to obtain beneficial effects from unsaturated fats. Trans fats have been implicated in increased rates of obesity, type 2 diabetes, some types of cancer and even Alzheimer’s disease.

Good heart health

The well-known Mediterranean Diet is rich in fish, vegetables, nuts and healthy oils and is consistently associated with good heart health. Virgin olive oil, an integral part of this diet, contains monounsaturated fatty acids. When it is refined to remove colour or flavour, its health benefits may be compromised. Cooking with virgin olive oil strongly reduces the risk of heart disease and stroke.

As nutrition science evolves, we learn more about how what we feed ourselves influences our ability to fight disease. Now we are learning that the quality, not just the quantity, of food that we eat has direct effects on health.

This is an extract from Dr Nikki Stamp’s book Can You Die of a Broken Heart? (Murdoch Books, £16.99). It is available to buy now in bookshops and at online retailers.

Read previous Your Health articles here...

Read articles from our latest issue here...