What is Cholesterol?
You have probably heard that high cholesterol increases your risk of heart disease. But what exactly is it, and what does it do?
Cholesterol is a waxy, fatty substance found in all your body cells. Our bodies require cholesterol to produce hormones, vitamin D, and substances that aid digestion.
Usually, the liver makes enough. However, you can also get cholesterol from consuming animal products, i.e., dairy, meat, and poultry products.
Now, cholesterol circulates in your blood. So when you have high levels of it, fatty deposits (plaques) can form in your arteries, decreasing blood flow.
The buildup of plaque in your coronary arteries can lead to coronary artery disease (CAD). CAD refers to the narrowing or blocking of the arteries that supply oxygenated blood to your heart.
Types of Cholesterol
Cholesterol is a type of lipid. And like other lipids, it needs to be attached to proteins to flow through your blood.
When lipids and proteins combine, they form a lipoprotein. Cholesterol classification depends on the function of the lipoprotein. Here are the different types of lipoproteins:
- High-density lipoprotein (HDL): commonly referred to as “good” cholesterol because it carries cholesterol from other parts of your body to your liver, where it’s broken down and eliminated from your body via the bile.
- Low-density lipoprotein (LDL): usually said to be “bad” cholesterol because high levels can contribute to the buildup of plaque in your arteries. Consequently, your arteries become narrow and clogged. And this puts you at risk of heart attack, stroke, and peripheral artery disease (PAD) because it transports cholesterol throughout the body, including your heart and limbs.
- Very low-density lipoprotein (VLDL): mainly carries triglycerides from your liver but transports some cholesterol as well. Triglycerides are the most common type of fat in your body. A high level contributes to fatty deposits in your artery walls, increasing your risk of heart disease.
Causes of High Cholesterol
Lifestyle
High cholesterol is mainly a result of how you live. Your body makes all the cholesterol it needs.
However, an unhealthy lifestyle can result in the production of too much cholesterol. Here are lifestyle choices that can negatively impact your cholesterol levels:
- Unhealthy diet. Eating certain foods can result in high LDL (bad) cholesterol. These include foods containing saturated fats (e.g., full-fat dairy products, fatty meat, processed meat, and baked goods) and trans fats (e.g., fried foods and baked goods).
- Little to no physical activity. Not getting enough exercise lowers your HDL (good) cholesterol. It can also make you gain weight, leading to increased cholesterol.
- Smoking. Cigarette smoking lowers your level of HDL “good” cholesterol.
Genetics
Your heredity can contribute to high cholesterol, where you inherit familial hypercholesterolemia (FH) from your mother, father, or grandparents. FH is a genetic disorder characterized by high LDL “bad” cholesterol levels.
Its severity depends on the duration and level of LDL cholesterol in the blood. Familial hypercholesterolemia is also known to cause coronary heart disease at an early age.
Risk Factors
Various factors can raise your risk for high cholesterol. These include:
Age. Increased cholesterol levels can be associated with aging. For starters, your liver function, which includes removing LDL cholesterol, declines as you get older.
Weight. If you’re overweight (BMI of 25–29.9) or obese (BMI of 30 or greater), you’re more likely to have high cholesterol.
Lack of exercise. Engaging in physical activity boosts your HDL cholesterol and makes your LDL cholesterol less harmful by increasing LDL particle size.
Diet. Foods that are high in saturated fat, trans fat, and cholesterol put you at risk of high cholesterol.
Diabetes. High blood sugar lowers HDL “good” cholesterol levels and results in an elevated VLDL and LDL level. It also damages the inner linings of your arteries, making them more likely to accumulate fatty deposits.
Smoking. Smoking cigarettes contributes to blood vessel damage, which makes them more prone to collect fatty deposits. It may also lower your HDL cholesterol levels.
High Cholesterol Symptoms
High cholesterol does not manifest any symptoms. The only way to detect high cholesterol levels is to get a blood test.
Complications
High cholesterol can lead to the development of atherosclerosis. Atherosclerosis is the buildup of plaque (cholesterol, fatty deposits, and other substances) in and on your artery walls.
Plaque causes your arteries to narrow, restricting blood flow, which, in turn, results in complications such as:
- Coronary heart disease (CAD): results from plaque buildup in your coronary arteries. Symptoms can range from chest pain (angina) to shortness of breath to none whatsoever.
- Heart attack: occurs when blood flow to the heart muscle gets obstructed.
- Stroke: occurs when blood flow to the brain is interrupted or reduced. Without early treatment, a stroke may result in permanent brain damage.
- Peripheral artery disease (PAD): also caused by atherosclerosis, PAD is a circulatory condition in which peripheral arteries become narrowed, reducing blood flow to your limbs.
How to Diagnose High Cholesterol
Your doctor will check your cholesterol levels using a blood test called a complete cholesterol test, which is also called a lipid profile or lipid panel.
The test measures the level of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides.
For accurate results, your doctor may ask that you don’t eat anything, drink certain beverages, or use certain medications for 9 to 12 hours before the blood test.
The general recommendation is for children to get one cholesterol test when aged 9 to 11, then another when they are aged 17 to 19. Adults at average risk for heart disease should undergo routine screening every five years.
However, more frequent testing may be necessary if the test results are undesirable or if your family has a history of high cholesterol, diabetes, heart disease, or other risk factors.
Cholesterol Levels Chart
The US measures cholesterol level in mg/dL, i.e., milligrams of cholesterol per deciliter of blood.
However, in other areas such as the UK and Canada, cholesterol levels are measured in mmol/L, i.e., millimoles per liter. Use these readings based on US guidelines to interpret your cholesterol test results.
Total cholesterol readings
| mg/dL | mmol/L | Results |
| Below 200 | Below 5.2 | Healthy |
| 200-239 | 5.2-6.2 | Borderline high |
| Above 240 | Above 6.2 | High |
LDL Cholesterol Readings
| mg/dL | mmol/L | Results |
| Below 70 | Below 1.8 | Ideal for individuals diagnosed with heart disease or diabetes |
| Below 100 | Below 2.6 | Appropriate for individuals at risk of heart disease |
| 100-129 | 2.6-3.3 | Favorable but high for individuals with heart disease. |
| 130-159 | 3.4-4.1 | Borderline high. High if diagnosed with heart disease. |
| 160-189 | 4.1-4.9 | High but especially high for people with heart disease. |
| 190 or higher | Above 4.9 | Very high |
HDL Cholesterol Readings
| mg/dL | mmol/L | Results |
| Men: readings below 40 Women: readings below 50 | Men: readings below 1 Women: readings below 1.3 | Poor |
| Men: readings between 40 to 59 Women: readings between 50 to 59 | Men: readings between 1 to 1.5 Women: readings between 1.3 to 1.5 | Better |
| 60 and higher | Above 1.5 | Optimal |
Triglyceride Readings
| mg/dL | mmol/L | Results |
| Below 150 | Below 1.7 | Desirable |
| 150 to 199 | 1.7 to 2.2 | Borderline high |
| 200 to 499 | 2.3 to 5.6 | High |
| 500 and above | Above 5.6 | Very High |
How to Lower Cholesterol
Making lifestyle changes will often improve your cholesterol levels. These changes include:
- Eating a heart-healthy diet: features fruits, vegetables, whole grains, lean meat, poultry, fish, legumes, and low-fat dairy products, while limiting saturated fat, trans fat, sodium, high-sugar foods, sugar-sweetened beverages, and eating foods low in cholesterol.
- Engaging in regular physical activity: getting at least 150 minutes of moderate-intensity aerobic activity weekly can help lower your cholesterol level.
- Quitting cigarette smoking or vaping: smoking lowers your HDL “good” cholesterol levels. If you are a non-smoker, you should avoid inhaling secondhand smoke.
- Losing weight: getting rid of as little as 5-10 percent of extra weight can improve your cholesterol levels.
Cholesterol medications
For some, lifestyle changes may be enough to reduce unhealthy cholesterol levels. However, others require medication to treat high cholesterol.
The choice of drugs depends on factors such as age, health status, and possible side effects. Common cholesterol-lowering drugs include:
- Statins: prevent cholesterol production by your liver, reducing cholesterol in your blood. Satins mainly lower LDL “bad” cholesterol and should not be taken by pregnant women or people with active or chronic liver disease. They include Atorvastatin (Lipitor®), Fluvastatin (Lescol®), Lovastatin (Mevacor®, Altoprev™), Pravastatin (Pravachol®), Rosuvastatin (Crestor®), and Simvastatin (Zocor®).
- Ezetimibe (cholesterol absorption inhibitor): the drug reduces cholesterol in your blood by preventing your intestines from absorbing cholesterol from your diet.
- Bile acid sequestrants/bile acid-binding agents: reduce blood cholesterol by binding to bile acids, which are crucial for digestion and made by your liver from cholesterol. They include Cholestyramine (Questran®, Locholest®), Colestipol (Colestid®), and Colesevelam (WelChol®).
- PCSK9 inhibitors: lower your cholesterol levels by causing the liver to absorb more LDL “bad” cholesterol. Alirocumab (Praluent) and evolocumab (Repatha) are some examples of PCSK9 inhibitors.
If a complete cholesterol test shows you have high triglyceride levels, your doctor may also prescribe fibrates, niacin (nicotinic acid), or omega-3 fatty acid supplements.
How to Prevent High Cholesterol
Your first line of defense against high cholesterol is to make healthy lifestyle changes.
Try losing extra pounds and maintaining a healthy weight, eating a heart-healthy diet, exercising regularly, and do away with smoking.
Remember, taking action to prevent it reduces your risk of coronary heart disease and stroke.
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- High blood cholesterol: What you need to know. (2020). nhlbi.nih.gov/files/docs/public/heart/wyntk.pdf.
- LDL and HDL cholesterol: “Bad” and “good” cholesterol. (2020). cdc.gov/cholesterol/ldl_hdl.htm.
