What is dyslipidaemia (high cholesterol)?

Dyslipidemia is a medical condition that refers to an abnormal level of blood lipids. The most common type of dyslipidemia is hyperlipidemia or high lipid levels. Another less common form of dyslipidemia, hypolipidemia, refers to lipid levels that are abnormally low.

Dyslipidemias can affect any lipid parameter, including LDL cholesterol levels, HDL cholesterol levels, triglycerides, or a combination of these lipids.

When only cholesterol levels are high or low, this is referred to as hypercholesterolemia or hypocholesterolemia respectively. Sometimes these may also be called a hyperlipoproteinemia or hypolipoproteinemia. When triglycerides are only affected, this may be referred to as hypertriglyceridemia (high triglyceride levels) or hypotriglyceridemia (low triglyceride levels). Conversely, if an individual has both triglyceride and cholesterol levels affected, this is referred to as a “combined” or “mixed” dyslipidemia.

Causes

There are many factors that can cause dyslipidemia—ranging from inherited disorders to your lifestyle. The causes of dyslipidemia can be divided into two main categories: primary or secondary dyslipidemia. 

• Primary dyslipidemia refers to abnormal lipid levels that are caused by a mutated gene or genes inherited from one or both parents.
• Secondary dyslipidemia, on the other hand, is more common and occurs due to a variety of factors involving certain aspects of your lifestyle or certain medical conditions you may have.

Cholesterol is carried through your blood, attached to proteins. This combination of proteins and cholesterol is called a lipoprotein. You may have heard of different types of cholesterol, based on what type of cholesterol the lipoprotein carries. They are:

• Low-density lipoprotein (LDL). LDL, or "bad," cholesterol transports cholesterol particles throughout your body. LDL cholesterol builds up in the walls of your arteries, making them hard and narrow.
• High-density lipoprotein (HDL). HDL, or "good," cholesterol picks up excess cholesterol and takes it back to your liver.

Factors within your control — such as inactivity, obesity and an unhealthy diet — contribute to high LDL cholesterol and low HDL cholesterol. Factors beyond your control may play a role, too. For example, your genetic makeup may keep cells from removing LDL cholesterol from your blood efficiently or cause your liver to produce too much cholesterol.

Risk Factors

Factors that may increase your risk of high cholesterol include:

• Poor diet. Eating saturated fat, found in animal products, and trans fats, found in some commercially baked cookies and crackers, can raise your cholesterol level. Foods that are high in cholesterol, such as red meat and full-fat dairy products, will also increase your total cholesterol.
• Obesity. Having a body mass index (BMI) of 30 or greater puts you at risk of high cholesterol.
• Large waist circumference. Your risk increases if you are a man with a waist circumference of at least 40 inches (102 centimeters) or a woman with a waist circumference of at least 35 inches (89 centimeters).
• Lack of exercise. Exercise helps boost your body's HDL, or "good," cholesterol while increasing the size of the particles that make up your LDL, or "bad," cholesterol, which makes it less harmful.
• Smoking. Cigarette smoking damages the walls of your blood vessels, making them likely to accumulate fatty deposits. Smoking may also lower your level of HDL, or "good," cholesterol.
• Diabetes. High blood sugar contributes to higher LDL cholesterol and lower HDL cholesterol. High blood sugar also damages the lining of your arteries.
• Certain medications such as beta blockers, certain drugs to treat HIV, oral contraceptives
• Liver disease
• Alcohol abuse
• Hypothyroidism that has not been treated
• Secondary hypolipidemias, which are less common, may be caused by untreated hyperthyroidism or certain cancers.

Signs and Symptoms

There is no true way of knowing whether or not you have a dyslipidemia – whether hyperlipidemia or hypolipidemia – unless you have a lipid panel performed. This involves having blood drawn for lab test and having it analyzed for levels of LDL, HDL, and triglycerides. In rare cases of extremely high lipids raised, yellowish bumps referred to as xanthomas may appear on the body. 

Complications

High cholesterol can cause atherosclerosis, a dangerous accumulation of cholesterol and other deposits on the walls of your arteries. These deposits (plaques) can reduce blood flow through your arteries, which can cause complications, such as:

• Chest pain. If the arteries that supply your heart with blood (coronary arteries) are affected, you may have chest pain (angina) and other symptoms of coronary artery disease.
• Heart attack. If plaques tear or rupture, a blood clot may form at the plaque-rupture site — blocking the flow of blood or breaking free and plugging an artery downstream. If blood flow to part of your heart stops, you'll have a heart attack.
• Stroke. Similar to a heart attack, if blood flow to part of your brain is blocked by a blood clot, a stroke occurs.

Prevention

The same heart-healthy lifestyle changes that can lower your cholesterol can help prevent you from having high cholesterol in the first place. To help prevent high cholesterol, you can:

• Eat a low-salt diet that includes many fruits, vegetables and whole grains
• Limit the amount of animal fats and use good fats in moderation
• Lose extra pounds and maintain a healthy weight
• Quit smoking
• Quit alcohol
• Exercise on most days of the week for at least 30 minutes.

How Does Exercise Help?

Management of dyslipidaemia is aimed at reducing the absolute risk of cardiovascular (CV) ‘events’ such as myocardial infarction (heart attacks) that may occur over the next 5-10 years. Lowering the LDL-c and triglycerides and increasing HDL-c can help to reduce this CV risk.

Because most cholesterol is transported as LDL-c, the recommended targets for maximal benefit are:

• Less than 2.5 millimoles per litre (mmol/L) for LDL-c in healthy people;
• Less than 1.8 mmol/L for LDL-c in people with existing heart disease;
• Greater than 1.0 mmol/L for HDL-c; and,
• Less than 2.0 mmol/L for triglycerides2

The prescription of statin therapies for dyslipidaemia has received a great deal of attention of the past 5-10 years. Management of cardiovascular risk should include a strong focus on lifestyle changes, including regular physical activity and exercise as well as improving the diet and reducing body fat. Exercise is a low-cost, readily available treatment modality with proven benefits for lipid and lipoprotein levels.

So What Are The Recommendations For High Cholesterol & Exercise?

Aerobic exercise

The American Heart Association has the following recommendations for including exercise in your healthy lifestyle:

• For your overall heart health, you should fit in 30 minutes of moderate aerobic exercise daily for at least 5 days a week.
• For specifically lowering lipids, you should be including at least 40 minutes’ worth of moderate to vigorous exercise at least three to four times a week.

If you can’t fit a 30- or 40-minute exercise regimen into your busy day, don't worry. You can divide your time up into 10- or 15-minute intervals to achieve the total recommended amount of exercise daily and get the same health benefits.

In order to improve lipid profiles and reduce cardiovascular risk, people with high cholesterol should aim for aerobic exercise for at least 30 minutes on most, if not all, days of the week. A useful strategy of doing so may shorter bouts of 10 minutes at a time and building up.

Examples of aerobic exercise are brisk walking, jogging, cycling, swimming dancing, ball games or other sporting activities.

Regular aerobic exercise can:
a) increase HDL-c by 3-10% (up to 0.16 mmol/L); and,
b) reduce triglycerides by about 11% (up to 0.34 mmol/L).

Vigorous exercise can improve HDL-c levels more so than low intensity exercise.

A good way to determine exercise intensity is to exercise at intensity where you can maintain a conversation without getting too short of breath.

Anaerobic Exercise (Resistance training)

Resistance training (weights) can also help to reduce lipid and lipoprotein levels. Generally 2-3 sets of 8-10 different exercises at a moderate level of intensity (able to do 8-12 repetitions), twice a week can help to improve HDL-c levels6.

It is advisable to start with a general aerobic warm up of 5-10 minutes prior to carrying out resistance training. Ensure that appropriate technique is used for each exercise to reduce the risk of injury. Self-administered vigorous aerobic or resistance training may not be suitable for all people with high cholesterol.

People with other underlined medical conditions such as those listed below would also benefit from a structured exercise program delivered by a chartered physiotherapist: 

• People with known CV disease, metabolic syndrome or diabetes
• People with a family history of CV disease
• People with hypertension (high blood pressure)
• Smokers
• Men aged over 45 years and women aged over 55 years
• People who have not been doing regular physical activity or exercise.

References:

1. Sullivan D.R., Watts G.F., Nicholls S.J., Barter P., Grenfell R., Chow C.K., Tonkin A. and Keech A. (2015). “Clinical guidelines on hyperlidipaemia: Recent developments, future challenges and the need for an Australian review”. Heart, Lung and Circulation 24: 495-502.

2. National Heart Foundation of Australia and the Cardiac Society of Australia and New Zealand (2012). “Reducing the risk in heart disease: an expert guide to clinical practice for secondary prevention of coronary heart disease. Melbourne: National Heart Foundation of Australia.

3. Kelley G.A., Kelley, K.S. and Franklin B (2006). “Aerobic exercise and lipids and lipoproteins in patients with cardiovascular disease: a meta-analysis of randomized controlled trials”. Journal of Cardiopulmonary Rehabilitation. 26(3): 131-9.

4. Exercise is Medicine (2014). “Exercise is medicine Australia factsheet: Dyslipidaemia and exercise”. www.exerciseismedicine.org.au

5. Braith R.W. (2006). “Resistance exercise training: its role in the prevention of cardiovascular disease”. Circulation. 113(22): 2642-2650.