How does cholesterol relate to cardiovascular disease?
For example, it helps build cell membranes; aids in the production of hormones, including estrogen and testosterone; and is critical to the process of fat absorption from food.
Too much blood cholesterol can lead to artery damage and cardiovascular disease.
Cholesterol comes from two sources:
- The foods you eat, which provide 15% to 20%
- Your liver, which produces 80% to 85%
When your cholesterol levels are higher than normal, you’re considered to have “high cholesterol,” which is also known as “hyperlipidemia” or “hypercholesterolemia.”
High blood cholesterol strongly increase your chances of having a heart attack or developing cardiovascular disease, it also puts you at greater risk for other serious health problems, such as the following:
- Coronary artery disease
- High blood pressure
Cholesterol is carried in the body by particles called lipoproteins — a type of cholesterol.
There are three main components of cholesterol you should know about:
1. LDL (low-density lipoprotein): Sometimes called “bad” or “lousy” cholesterol, LDL carries most of the cholesterol in the blood to be stored away for future use. High levels of LDL cause cholesterol to build up on artery walls, leading to plaque formation.
Too much LDL can lead to a buildup of cholesterol (plaques) on the walls of blood vessels, causing them to narrow or harden and restrict blood flow. This is known as atherosclerosis.
Narrowing of the blood vessels that lead to the heart can cause coronary artery disease, angina, and heart attack. Heart attacks result when plaques rupture, breaking away from the wall of a blood vessel, and block an artery. Narrowing of the blood vessels leading to the brain can cause stroke.
2. HDL (high-density lipoprotein): Called “good” or “healthy” cholesterol, HDL carries cholesterol from the body to the liver, where it is eliminated. The more HDL you have in your blood, the better protected you are against the buildup of plaque in your arteries.
When your HDL cholesterol is too low, harmful cholesterol stays in the arteries instead of being transported to the liver and ultimately eliminated from the body.
3. Triglycerides (TC): This is the most common type of fat in your body. Triglycerides have a dual function, acting to both store and transport fat in the blood. When you eat excess calories (especially sugar and alcohol), they are stored as triglycerides.
Similar to LDLs, excess triglycerides increase your risk for cardiovascular disease. High triglyceride levels are dangerous to your cardiovascular health because they increase the likelihood of hardening of the arteries, which raises the risk for heart disease, stroke, and heart attack.
Total cholesterol/HDL (TC/HDL) is a ratio used to measure your cardiovascular risk. TC/HDL is calculated by dividing your total cholesterol number by your total HDL cholesterol number.
Who is at risk of high cholesterol?
Cholesterol levels generally are lower in younger women than younger men, but above the age of 65 they are much higher in women. If you have high levels of LDL cholesterol, your doctor may prescribe cholesterol-lowering medication, changes to your diet and exercise.
However, no matter your gender, age, or ethnicity, you are at risk for high cholesterol.
The following factors may put you at increased risk for high cholesterol. If one or more of these applies to you, see your doctor to have your cholesterol tested:
- You’re a man 40 years or older
- You’re a woman 50 years or older or are past menopause
- You have a first-degree relative younger than age 60 who died of cardiovascular disease
- You’ve experienced a previous heart attack or stroke
- You have diabetes
- You have high blood pressure
- You have kidney disease
- You smoke
- You are not at your healthiest weight
- You have an inflammatory disease.
- You have HIV
Causes of high cholesterol
Some causes of high cholesterol are beyond your control. High cholesterol can be hereditary, and levels of LDL naturally rise as people get older. Your cholesterol is also influenced by these unchangeable factors including age, family history and gender (risk increases for post-menopausal women).
There are factors, or habits, you can change that negatively impact your cholesterol. These include:
- Getting too much saturated fat, trans fat, and cholesterol in your diet
- Not living at your healthiest weight
- Lack of exercise
- High blood pressure
How Do I Know If I Have High Cholesterol?
There are no symptoms for high cholesterol. Many people with high cholesterol are not aware their levels are high, putting them at risk for cardiovascular disease. Your doctor will calculate your level of risk (low, moderate or high) using a specific evaluation tool and factors such as previous heart attack and/or stroke, artery blockages in your neck, arms, or legs, diabetes, age and two or more risk factors, such as smoking, high blood pressure, low HDL, or a family history of CVD.
If none of the above-mentioned factors applies to you, and you are older than 20 years of age, your doctor will decide whether it’s necessary for you to be tested and how often. The blood test is taken after you have fasted overnight or for 10 to 12 hours. It measures your total cholesterol, triglycerides, LDL, and HDL levels. Total cholesterol/HDL (TC/HDL) is a ratio used to measure your cardiovascular risk. TC/HDL is calculated by dividing your total cholesterol number by your total HDL cholesterol number.
What if my cholesterol levels are too high?
There are two main tools for managing cholesterol and many patients require both: medication and changes in lifestyle. Making recommended lifestyle changes can improve your cholesterol by 5% to 10%, but medications have been shown to lower LDL-cholesterol by 20% to 55%. As a result, medication is often required in combination with lifestyle changes, such as quitting smoking and increasing exercise.
Different drugs lower LDL and triglycerides, raise HDL, and reduce the amount of cholesterol absorbed in the digestive system. A patient may take more than one cholesterol-lowering drug at the same time.
All patients who already have coronary heart disease or diabetes should be treated with a statin. Statins are safe and effective drugs for lowering cholesterol. Some patients may require the addition of a second medication.
Drug therapy guidelines for high triglycerides are not as clear-cut as they are for cholesterol. However, fibrates are the drug of choice for lowering triglycerides in the very high range for people whose cholesterol levels are relatively normal. The most potent fibrates can lower triglycerides by 40%. Statins are effective against both cholesterol and triglycerides. Successful treatment requires consistent blood sugar control for people with diabetes and avoidance of alcohol, oral estrogen, and retinoids.
Treatment of Low HDL
The B vitamin niacin is capable of increasing HDL by 30% (and often by an even higher percentage with prolonged treatment). It is the most effective agent for increasing HDL levels.
Medications are commonly prescribed if you are at high risk for CVD, or you are at moderate risk and have additional risk factors. If you’ve been prescribed medication, it’s important to follow the prescription plan your doctor has set up for you. Remember to:
- Never stop taking your medication just because you are feeling better.
- Write down any symptoms you may experience so that you can remember to discuss them with your doctor.
- Keep track of your medication, especially if you are taking multiple pills. A pocket medication card can help.
- Be on time and consistent with your medication so that it remains effective.
For most people, medication alone isn’t enough. Most of your cholesterol comes from the food you eat, but there’s more to managing cholesterol than watching what you eat. Learn more about the most important lifestyle changes and how to get started. Important lifestyle changes for lowering cholesterol include:
- Eating a healthy diet high in fibre and low in saturated fat, trans fat, and cholesterol
- Losing weight
- Increasing exercise
- Quitting smoking
- Managing diabetes
Knowing your cholesterol level is an important step to good heart-health. High cholesterol affects almost half of Canadians aged 40 to 59 and more than a quarter of Canadians between the ages of 20 and 39, but many people with high cholesterol have no idea their levels are high. Talk to your doctor to see if you should have your cholesterol measured, and for advice on managing your cholesterol. To achieve healthy cholesterol levels, many patients require both cholesterol-lowering drugs and changes in lifestyle habits.
Best practice guidelines
Download the 2016 Canadian Cholesterol Guidelines.