Even if you’ve never thought about cholesterol before, there’s a good chance you know that high cholesterol is bad. If a person’s levels are too high, it can increase their risk of heart attack and stroke, as well as conditions such as peripheral arterial disease.
Before you start to panic, though, it’s not all doom and gloom – particularly if you’re a runner. Cardiovascular endurance exercise such as running is recommended to help people keep their cholesterol in check, as it helps to not only lower levels of ‘bad’ cholesterol but has also been found to increase levels of ‘good’ cholesterol too (more on that later).
That doesn’t mean you can stick your fingers in your ears if you run, though. Exercise alongside other lifestyle choices, including nutrition, alcohol consumption and smoking, aren’t the only factors that can impact your cholesterol levels and are generally only a small piece of the puzzle. High cholesterol can run in families and is also influenced by things like your age, sex, ethnic background and weight, and can be caused by some health conditions.
But before we get into the nitty gritty, it’s useful to begin by looking at what cholesterol actually is…
What is cholesterol?
‘Cholesterol is a sterol – a family of small molecules – and is an essential structural ingredient of the membrane around all our cells,’ explains Dr Nigel Stephens, consultant cardiologist at the Institute of Sport, Exercise and Health.
Produced in the liver and also in some of the foods we eat, cholesterol is used to keep the cells in the body healthy and is transported around the body by proteins in our blood.
Combined, cholesterol and proteins are called lipoproteins. The two main types of lipoprotein are: low-density lipoprotein (LDL) which gets referred to as ‘bad’ cholesterol and high-density lipoprotein (HDL) or ‘good’ cholesterol. LDL transports cholesterol from the liver to cells in the blood and HDL carries cholesterol away from the cells and back to the liver where it’s either broken down or passed out the body as a waste product.
What is high cholesterol?
Your cholesterol level is a measure of how much total cholesterol there is in your blood, which can be broken down further into the different types of cholesterol: LDL, HDL and triglycerides (a type of fat found in your blood). Measured in mmol/L, the NHS suggests that a total cholesterol below 5mmol/L is healthy. It recommends that this should be made up of above 1mmol/L of HDL for men or above 1.2mmol/L of HDL for women and below 4mmol/L of non-HDL cholesterol for both sexes.
It’s not an exact science, though. ‘What’s high depends on how old you are,’ explains consultant cardiologist Dr Mark Dayer. ‘What we tolerate, or need to treat, also depends on what other conditions you have. If you’re 90 and have a [total] cholesterol of 6mmol/L, we wouldn’t necessarily be too worried. But if you’re 16 and you have a cholesterol of 6mmol/L, there’s a family history of heart disease and everyone else has got a high cholesterol, then you might think “I need to treat that.”‘
In addition to the NHS’ recommendations, Stephens says that a ratio of HDL to total cholesterol greater than five is ‘something you really need to do something about’ with prescribed medication such as statins, while for a ratio of less than five, ‘lifestyle measures will generally suffice’.
Both Stephens and Dayer suggest looking at QRisk3 to get an understanding of your risk of developing a heart attack or stroke over the next decade based on factors such as age, sex, and ethnicity and clinical information such as BMI and whether you smoke.
How to know if you have high cholesterol
High cholesterol is something of a symptomless health risk. The easiest way to know if you have high cholesterol is to have a blood test, which your GP may recommend, especially if you have a close family member who has a cholesterol-related condition.
What are the dangers of having high cholesterol?
High levels of LDL or ‘bad’ cholesterol can become fatal over a lifetime as it builds up in a person’s arteries.
‘As LDL circulates in the blood, it gradually becomes oxidised – just like butter becomes rancid at room temperature,’ explains Stephens. ‘Oxidised LDL particles are harmful. They interact with inflammatory cells in the lining of our blood vessel wall and high levels of oxidised LDL are a causative factor in developing atherosclerosis – the hardening and narrowing of arteries.’
Any artery can fur up, and this increases the risk of ‘heart attacks, strokes, vascular dementia, as well as toes falling off and impotence in men’, explains Dayer.
Risk factors of getting high cholesterol
High cholesterol can be caused by many different factors – some of these are controllable and others, unfortunately, aren’t.
The biggest risk factor in getting high cholesterol is your genetics, explains Stephens. ‘Generally 85% of the variation between person to person is due to their genetic background,’ he says. Genetic high cholesterol is called familial hypercholesterolaemia (FH for short), and means there is a fault in one of the genes involved in removing cholesterol from the blood. Usually, a high-intensity statin is needed to bring it down.
Your age, biological sex and ethnic background also influence your cholesterol levels. Cholesterol and triglyceride levels naturally rise throughout adult life meaning your risk increases as you get older. Men are also more likely to have high cholesterol than women, as are those from a South Asian background. Some medical conditions, such as having an under-active thyroid, can also be a cause.
However, lifestyle factors including excess alcohol consumption, being overweight, smoking, an unhealthy diet (including eating too much saturated fat) and not being physically active can all increase your levels. Thankfully, these factors are changeable, and you can lower your cholesterol by eating healthily and exercising more – including running.
Does running lower cholesterol?
Exercise is clinically proven to lower cholesterol levels. Research shows that regular physical activity increases HDL cholesterol (‘good’ cholesterol) while maintaining, and theoretically offsetting increases in, LDL (‘bad’ cholesterol) and triglycerides. ‘People who are active, particularly with endurance and aerobic activities, tend to have high HDL cholesterol levels, almost certainly because there’s something about being physically active that causes a more rapid turnover in your cholesterol metabolism,’ explains Stephens.
Running specifically has also been shown to have a dose-response relationship with cholesterol, where miles run can have a direct, positive impact. A study published in Jama Internal Medicine found a gradual increase in HDL with increased miles, with most changes associated with running distances of 7 to 14 miles per week at mild to moderate intensities. Levels of LDL, triglycerides and the ratio of total cholesterol to HDL were also found to improve with weekly mileage.
Another study, published in Arch Intern Med, found that dedicated long-distance runners (those clocking more than 80km a week) saw the biggest benefits to their cholesterol levels. The research found an 85% reduced prevalence of HDL levels that were clinically low and a 2.5-fold increased prevalence of clinically defined high levels of HDL, compared with runners who clocked less than 16 km (10 miles) per week.
Can I get my cholesterol down to safe levels through diet and exercise?
For some, lifestyle changes may not be enough to lower their high cholesterol levels, in which case, a doctor may suggest medication.
Stephens and Dayer agree that the most effective way to reduce dangerously high levels of cholesterol is with medication such as statins, which lowers LDL by inhibiting an enzyme in the liver called HMG-CoA reductase – one of the key enzymes in the synthesis of cholesterol. ‘Realistically, if we’ve got a high vascular risk, it’s going to be treated with medication,’ says Stephens.
Dayer, however, highlights the importance of making ‘marginal gains’ through healthy lifestyle choices. ‘What you’re trying to do is mitigate the effects of a high cholesterol by doing all these other things. They won’t necessarily lower your cholesterol to any great extent because disappointingly a lot of it is to do with genetics and age.
‘[But] when you change your diet, and you change your lifestyle, you’re changing a lot more things than just cholesterol. If you make those changes you should be proud of that, and you should be confident that that’s going to make you live longer.’
The British Heart Foundation recommends swapping saturated fats (including processed food, red meat, full-fat dairy) with foods that are high in unsaturated fat like vegetable oils (sunflower, olive and rapeseed oil), nuts, seeds and avocado and oily fish, which can help to lower LDL levels.
Eating foods that are high in fibre can also help to lower your LDL by reducing the amount of cholesterol that is absorbed into the blood stream from your intestine. For this reason Harvard Health recommends including oats, whole grains, beans and plenty of fruits and vegetables in your diet.
Does fasting lower cholesterol?
Your total cholesterol is made up of LDL, HDL and triglycerides, and the triglycerides bit goes up and down depending on what you’ve just eaten, explains Dayer. ‘So you can affect your total cholesterol levels by fasting – if you fast enough your cholesterol levels will go down.’
However, he highlights that this isn’t sustainable as, naturally, ‘at some point, you’ve got to stop fasting’.