What is High Cholesterol?

Cholesterol is one of several types of fats (lipids) that are essential to good health. Because of its reputation as a risk factor for heart disease, people tend to think of cholesterol only in negative terms. But cholesterol is an important component of cell membranes and vital to the structure and function of all of your body's cells. Cholesterol also is a building block in the formation of certain types of hormones.

Still, about half of all Americans have a higher-than-desirable blood cholesterol level (hypercholesterolemia). If you're one of these people with this largely preventable condition, you may be on the way to heart disease.

When the levels of cholesterol and triglycerides, another blood fat, in your bloodstream become too high, your likelihood of developing cholesterol-containing fatty deposits (plaques) in your blood vessels increases. Over time, plaques narrow arteries, impeding blood flow and creating a condition called atherosclerosis. Narrowing of the arteries around your heart (coronary artery disease) can prevent your heart from getting as much oxygen-rich blood as it needs. This means an increased risk of a heart attack. Likewise, decreased blood flow to your brain can cause a stroke, and less blood flowing to your lower limbs may result in gangrene.

Signs and Symptoms

High blood cholesterol doesn't cause any signs or symptoms. The only way to find out if you have high blood cholesterol is a blood test.

Causes

Cholesterol is one of two lipids that circulate in your blood. Triglycerides are another form of fat that moves through your blood as transportable fuel used for energy.

Because they are fats, neither cholesterol nor triglycerides dissolve in water. To circulate in your blood, which is mainly water, cholesterol and triglycerides must be carried by proteins called apoproteins. A lipoprotein is a combination of a lipid and an apoprotein.

The main types of lipoproteins are:

• Low-density lipoprotein (LDL). LDL contains about 25 percent protein and 45 percent cholesterol. The cholesterol carried in LDL particles is known as LDL cholesterol. LDL cholesterol is sometimes called bad cholesterol because it transports cholesterol to sites throughout your body, where it's either deposited or used to repair cell membranes. But like hard water causing lime to build up inside plumbing, LDL cholesterol promotes accumulation of cholesterol in the walls of your arteries.
• High-density lipoprotein (HDL). HDL contains almost 50 percent protein and 20 percent cholesterol. The cholesterol carried in HDL particles is known as HDL cholesterol. HDL cholesterol helps clear excess cholesterol from your body and so is sometimes called good cholesterol.
• Very-low-density lipoprotein (VLDL). This type of lipoprotein contains mostly triglycerides and small amounts of protein and cholesterol.

You may have high LDL cholesterol as a result of genetic makeup or lifestyle choices, or both. Your genes can give you cells that don't remove LDL cholesterol from your blood efficiently, or a liver that produces too much cholesterol as VLDL particles. Your genetic makeup also can result in too few HDL particles.

Complications

High blood cholesterol can cause you to develop heart disease. The American Heart Association reports that heart disease kills almost 1 million Americans each year, more than all cancer deaths combined. Many of these deaths occur because of the accumulation of fatty deposits (plaques) on the walls of your arteries (atherosclerosis), resulting in narrowed or blocked arteries. Cholesterol plays a significant role in this largely preventable condition.

Atherosclerosis is a silent, painless process that results in reduced blood flow. If reduced flow occurs in the arteries around your heart (coronary arteries), it can lead to a type of chest pain called angina pectoris.

As a plaque enlarges, the inner lining of your artery becomes roughened. A tear or rupture in the plaque may cause a blood clot to form. Such a clot can block the flow of blood or break free and plug an artery downstream.

If the flow of blood to a part of your heart is stopped, you'll have a heart attack. If blood flow to a part of your brain stops, a stroke is imminent.

Risk Factors

These lifestyle choices can cause or contribute to high total cholesterol levels:

• Inactivity. Lack of exercise may lower your level of high-density lipoprotein (HDL) cholesterol, "good" cholesterol.
• Obesity. Excess weight increases your triglycerides. It also lowers your HDL cholesterol and increases your very-low-density lipoprotein cholesterol.
• Diet. Cholesterol naturally occurs in foods made from animals, such as meat, eggs and cheese. Eating a high-fat, high-cholesterol diet contributes to an increased blood cholesterol level. Saturated and trans fats raise blood cholesterol levels. Polyunsaturated fats lower blood cholesterol but also seem susceptible to oxidation. Over time, oxidation speeds buildup of plaques inside your arteries. Monounsaturated fats may help lower blood cholesterol and are resistant to oxidation.

• Smoking. Cigarette smoking damages the walls of your blood vessels, making them prone to accumulate fatty deposits. Smoking also may lower your level of HDL cholesterol by as much as 15 percent.
• High blood pressure. By damaging the walls of your arteries, high blood pressure can accelerate the accumulation of fatty deposits on the walls of your arteries.
• Type 2 diabetes. This type of diabetes generally develops after age 40. The condition results in a buildup of sugar levels in your blood. Chronic high blood sugar may lead to narrowing of your arteries.
• Family history of atherosclerosis. If a close family member (parent or sibling) has developed atherosclerosis before age 45, high cholesterol levels place you at a greater risk than average of developing atherosclerosis.

A good way to detect high blood cholesterol early so that you can take steps to improve your health is to have a regular blood test to measure your cholesterol level. Some doctors recommend having your levels of high-density lipoprotein (HDL) cholesterol - the so-called good cholesterol - and of triglycerides, another type of blood lipids, measured initially, as well as your total cholesterol level. A typical blood cholesterol test measures:

• Total cholesterol
• HDL cholesterol
• Triglycerides

Measuring only total cholesterol can be misleading because some people have low levels of HDL cholesterol and high levels of triglycerides, but normal or even high levels of LDL cholesterol. In these cases, a total cholesterol measurement might appear normal. You and your doctor would be unaware of the risk of heart disease posed by the abnormal levels that weren't measured. Even with a desirable total cholesterol level, if you have a low HDL level, you may be at increased risk for heart disease.

Desirable ranges for cholesterol levels vary depending on risk factors such as your age, gender, family history and health condition. There's no magic number that separates risky levels from safe levels. Rather, expert investigators and doctors have identified levels of lipids in the blood above which the risk for developing coronary complications is high enough to warrant lifestyle changes. Talk to your doctor about what level is appropriate for you.

Desirable values

If you're healthy:

• Total cholesterol: Below 200 milligrams per deciliter (mg/dL)
• Total triglycerides: Below 200 mg/dL
• HDL cholesterol: Above 45 mg/dL
• LDL cholesterol: Below 130 mg/dL

• Total cholesterol: Below 200 mg/dL
• Total triglycerides: Below 200 mg/dL
• HDL cholesterol: Above 35 mg/dL
• LDL cholesterol: Below 100 mg/dL

You can also purchase a home cholesterol test. These tests measure only total cholesterol, are less sophisticated than laboratory tests and may give unreliable results.

Treatment

Lifestyle changes are the first steps to take to improve your blood levels of cholesterol and triglycerides. These steps include changes in diet, exercising regularly and not smoking (see "Prevention"). But if you've made these important lifestyle changes and your total cholesterol - especially your level of low-density lipoprotein (LDL) cholesterol - remains high, your doctor may recommend prescription medication.

Before recommending medication, your doctor may weigh many variables - your changeable risk factors, your age, your current health and the drug's side effects. If you need a medication to improve your cholesterol levels, chances are you may need it for many years.

Your LDL cholesterol level is usually the deciding factor. If you have no risk factors for heart disease, an LDL level greater than 190 generally requires medication. With two or more risk factors, an LDL level greater than 160 may require medication. If plaques have narrowed the arteries around your heart and restricted the flow of oxygen-rich blood to your heart's muscles (coronary artery disease), your doctor may try medication and lifestyle changes to lower your LDL to less than 100.

Medications to improve blood cholesterol levels include:

• Resins. The medications cholestyramine (Questran) and colestipol (Colestid) lower cholesterol indirectly by binding with bile acids in your intestinal tract. Your liver makes bile acids, which you need for digestion, from cholesterol. By tying up bile acids, resins prompt your liver to make more bile acids. Because your liver uses cholesterol to make bile acids, less cholesterol is available to reach your bloodstream.
• Triglyceride lowering drugs. These medications include fibrates such as gemfibrozil (Lopid) and fenofibrate (Tricor), and niacin (nicotinic acid). Fibrates reduce triglyceride production and remove triglycerides from circulation. They often also increase your HDL cholesterol level.
• Statins. Statins work directly in your liver to block a substance your liver needs to make cholesterol. This depletes cholesterol in your liver cells, which causes your liver cells to remove cholesterol from your blood. Statins can reduce your LDL cholesterol by up to 40 percent. Statins also may help your body reabsorb cholesterol from plaques that accumulate on the walls of your arteries. This process slowly unplugs your blood vessels. Statins include fluvastatin (Lescol), lovastatin (Mevacor), simvastatin (Zocor), pravastatin (Pravachol), atorvastatin (Lipitor) and cerivastatin (Baycol).

Improving your blood cholesterol levels reduces your risk of heart disease. Lifestyle steps are your first course of action to improve your blood cholesterol levels. These steps include eating a healthy diet, exercising and not smoking.

Eating a healthy diet

These changes in your diet can improve your blood cholesterol levels:

• Control total fat. Limit all types of fat - saturated, polyunsaturated, trans fatty acids (trans fats) and monounsaturated - to no more than 30 percent of your total daily calories. Because all foods with fats contain a combination of these fats, it's important to reduce total fat. Not every food you eat must have less than 30 percent of its calories from fat. Use the guideline as a daily average. By balancing occasional high-fat foods with low-fat choices, your fat intake should average no more than 30 percent of your daily calories. If your daily intake is 2,000 calories, 30 percent equals 65 grams of fat. Limit saturated fat to no more than 10 percent of total calories.
• Limit dietary cholesterol. Your daily limit for dietary cholesterol is 300 milligrams. To accomplish this goal, limit or avoid concentrated sources such as organ meats, egg yolks and whole milk products.
• Eat foods with soluble fiber. As part of a low-fat diet, soluble fiber can help lower your total blood cholesterol level. Foods high in soluble fiber include oat bran, oatmeal, beans, peas, rice bran, barley, citrus fruits, strawberries and apple pulp.
• Eat more fish. Some fish - particularly fatty types prevalent in cold water such as salmon, mackerel and herring - contain high amounts of a unique type of polyunsaturated fat called omega-3 fatty acids. Omega 3s may lower your level of triglycerides.
• Consider soy products. Soy compounds called isoflavones act like human hormones that regulate cholesterol levels. Eating soy proteins can reduce your levels of total cholesterol, low-density lipoprotein (LDL) cholesterol and triglycerides. Eating soy may also raise your level of high-density lipoprotein (HDL) cholesterol - "good" cholesterol, which may protect you against heart disease.
• Eat more foods with antioxidants. Antioxidant vitamins may help prevent cholesterol from damaging the lining of your arteries. They include vitamins C and E and the carotenoids, such as beta carotene. Oxidation is the process by which cells in your body called free radicals damage other cells as they seek to replace their missing electron. Antioxidants neutralize free radicals by donating the electrons the free radicals need. Oxidation causes changes in fatty acids and LDL cholesterol in your blood. These changes enable cells in your arteries to absorb fatty acids and LDL cholesterol more easily, leading to plaque buildup and narrowing of your arteries.
• Drink alcohol in moderation, if at all. Moderate consumption of alcohol may raise your level of HDL cholesterol. The best advice is to drink in moderation if you drink at all. Limit alcohol to one drink daily if you're a woman, to no more than two drinks daily if you're a man. If you're a nondrinker, don't start drinking alcohol. Don't drink alcohol if you have a high level of triglycerides.

Being overweight promotes a high total cholesterol level. Losing weight improves your cholesterol levels. Set up an exercise program to lose weight using these guidelines and your doctor's advice:

• Choose an aerobic activity. Get involved in activities such as brisk walking, jogging, bicycling or cross-country skiing.
• Build up the time and frequency of exercising. Gradually work up to exercising for 30 minutes to 45 minutes at least three times a week. If you're significantly overweight or have been inactive for many years, take several months to gradually work up to this level. The higher the level of your activity, the greater your rate of weight loss.
• Stick with your exercise program. Schedule a regular time for exercise. Make exercise fun. If it's not enjoyable you may not feel like exercising regularly, year in and year out. Find a friend, or join an exercise group, to keep you motivated and committed to exercise. Or take up an activity that keeps you active.

If you smoke, stop. If you don't smoke, don't start. Cigarette smoking damages the walls of your blood vessels, making them prone to accumulate fatty deposits. If you stop smoking, your HDL cholesterol may return to its former level.