What you need to know about heart disease and blood lipids
Heart disease and stroke are the primary causes of death in Canada, in addition to being significant causes of disability for both men and women, and include:
- disease due to cholesterol build-up in the blood vessels in the heart (coronary heart disease or CHD);
- disease of other blood vessels (cardiovascular disease or CVD), which includes the vessels going down to your stomach, kidneys and legs (peripheral vascular disease or PVD); and disease of the blood vessels going to your brain (carotid artery disease or CAD).
In the 1960s, scientists coined the term “risk factors” to describe the personal traits and lifestyle habits that can contribute to our chances of being affected by heart disease and stroke. Some risk factors we have little or no control over (e.g., our age, gender or a family history of premature heart disease). There are other risk factors that we can control (e.g., diabetes, obesity, elevated blood cholesterol and triglycerides, elevated blood pressure, metabolic syndrome) or even change – in particular, our lifestyle habits. Too much food, too little exercise and smoking are the lifestyle habits that are primarily responsible for heart disease and stroke.
Additional technical information about lipid and non-lipid risk factors, and about medications that are commonly prescribed to lower levels of blood lipids, can be found on www.copingwithcholesterol.ca.
Lipid risk factors for heart disease
Blood lipids are fat-like substances in the blood, and include cholesterol, lipoprotein carriers of cholesterol and triglycerides. The levels of lipids in the blood are affected by a combination of factors, including diet, obesity, lifestyle habits, hormone levels, genetic factors and drug use, as shown in Table 1.
Table 1. Factors that affect blood cholesterol and triglyceride levels
| Raises LDL-C | Lowers HDL-C | Raises triglycerides |
| High saturated fat dietHigh intake of dietary cholesterol
Obesity Thyroid disease Renal disease Liver disease Genetic factors Certain drugs |
SmokingObesity
Inactive lifestyle High triglycerides Diabetes Genetic factors Certain drugs |
Excess sugar and sweetsAlcohol
Excess refined carbohydrate Obesity Poorly controlled diabetes Inactive lifestyle Genetic factors Certain drugs |
Cholesterol
Cholesterol is produced primarily by your liver, although some of the cholesterol in your blood comes from the food you eat. The most important types of cholesterol in the blood are:
- low density lipoprotein cholesterol (LDL-C), and
- high-density lipoprotein cholesterol (HDL-C).
Remember: LDL = Lousy cholesterol and HDL = Healthy cholesterol
LDL-C causes a build-up of cholesterol on the walls of your arteries that is known as plaque. Eventually, it can become so thick that it narrows the space in which blood moves – the lumen – and slows down or even blocks blood flow. Blocks can also occur when a piece of plaque breaks off. Angina – a chest tightness or pain in your left arm or jaw – is caused by poor blood flow in the heart muscle.
HDL-C picks up cholesterol from the walls of the arteries and returns it to the liver for recycling or excretion. The more HDL-C you have in your blood, the better protected you are against the build-up of plaque in your arteries.
Because there are no symptoms of high LDL-C or low HDL-C, only a blood test can tell your doctor whether or not your blood cholesterol levels are putting you at risk for heart disease or stroke.
Triglycerides
Triglycerides are another type of fat in your bloodstream. The liver produces triglycerides from the foods that you eat. Foods that are high in fat, sugar and alcohol make the liver produce more triglycerides. Being overweight (especially if you carry too much fat around your midsection) also makes the liver produce more triglycerides. High triglycerides increase the chances of blood clots forming in your arteries and can also lower HDL-C (healthy cholesterol) levels.
Reducing your risks
What can you do to reduce your risk of heart disease? Start by knowing the facts. Identify your risk factors for heart disease with your doctor and eliminate or modify as many of them as you can. When you take responsibility and control your risk factors, you deal heart disease a serious blow. It’s never too late to take control of your risk. A few changes in your lifestyle can lower your LDL-C and triglycerides and may even boost your HDL-C. Table 2 shows the effects that lifestyle changes can make on the levels of lipids in your blood.
Taking charge of your lifestyle means that you:
- Get moving! by incorporating physical activity in your life;
- Eat smart! by making better choices in your diet; and
- Shape up! by losing excess body weight.
A healthy heart is up to you! Read on…
Get Moving! – the effects of physical activity on blood lipids
Physical activities that are part of your daily routine as well as part of your recreational activities will help you achieve healthier blood lipid levels, especially in combination with weight loss. Table 2 shows the rewards of increasing physical activity. For example, an daily exercise program that includes 30 to 60 minutes of moderate to vigorous physical activities (fast walking, hiking, cycling, swimming, skating, cross country skiing, running) in combination with weight loss will increase HDL-C by 5-30%. The more time you spend being physically active, the greater the effect on your triglycerides. Weight loss in combination with physical activity can reduce triglycerides by 10-40%.
Section I of this booklet contains information on determining your readiness to increase your activity level, and how to choose an activity that is right for you and your lifestyle.
Eat smart! – dietary strategies to prevent heart disease
“Let food be thy medicine and medicine be thy food”.
– Hippocrates
Compelling evidence from research into nutrition over the past thirty years indicates that there are three dietary strategies that are effective in preventing heart disease:
- Eating a daily diet that consists mainly of unrefined plant foods – vegetables, fruit, legumes, whole grains, nuts and seeds – and minimal amounts of refined food products.
- Substituting non-hydrogenated unsaturated fats for saturated fats and trans fats.
- Choosing more often those plant and animal foods that are sources of omega-3 fatty acids such as fatty fish, plant oils, and omega-3 enriched eggs.
Section II – Eat Smart! – contains information on improving your diet by assessing where you need to make changes, and how to make heart-healthy choices.
Shape up! weight loss and blood lipids
Losing excess body fat and keeping it off will improve cholesterol and triglyceride levels and further reduce the risks of heart disease, diabetes and high blood pressure. Table 2 shows how much LDL-C and triglyceride levels can be reduced by losing as little as four kilos (10 pounds). Taking the next step and becoming physically fit while maintaining that weight loss can improve your HDL-C levels as well.
Section III contains information on identifying, achieving and maintaining a healthy body weight.
Table 2. Effect of lifestyle changes on blood lipid levels
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