Cholesterol 

Course Objectives

By completing this course the healthcare professional will be able to:                                  

1.   Identify the signs and symptoms of Coronary Heart Disease.

2.   Describe the role of cholesterol in Coronary Heart Disease.

3.   Identify what makes cholesterol levels high and low.

4.   Describe ways to lower cholesterol levels.

5.   Identify foods high in saturated fats and bad cholesterol.

 

Cholesterol - What it is and Where it Comes From

 Twelve to thirteen million American adults have coronary heart disease CHD, which is a major cause of disability and the number one killer of women and of men in the United States. In 1994, almost 500,000 people died from CHD, equally divided between men and women. About 1.25 million people have heart attacks every year, and about half of these occur in persons who are already known to have CHD. For men and women with CHD, the risk of a heart attack is five to seven times higher than for people of the same age and sex who do not have CHD.  By lowering cholesterol a person can reduce their risk of having a heart attack.

Most CHD patients will benefit from cholesterol lowering. In fact, people who already have heart disease, should pay even more attention to their cholesterol level, because they stand to benefit even more. A person with CHD has a much greater risk of having a future heart attack than a person without heart disease. If they lower their blood cholesterol level, they will definitely reduce their risk of a future heart attack and could actually prolong their life.

What Is Coronary Heart Disease?

You probably know that CHD is a type of heart disease caused by narrowing of the coronary arteries that feed the heart. Like any muscle, the heart needs a constant supply of oxygen and nutrients, which are carried to it by the blood in the coronary arteries. When the coronary arteries become narrowed or clogged by fat and cholesterol deposits and cannot supply enough blood to the heart, the result is CHD. If not enough oxygen-carrying blood reaches the heart, the person may experience chest pain called angina. If the blood supply to a portion of the heart is completely cut off by total blockage of a coronary artery, the result is a heart attack. This is usually due to a sudden closure from a blood clot forming on top of a previous narrowing.

The Role of Cholesterol in CHD 

What is cholesterol and what does it have to do with CHD? Cholesterol is a waxy substance that occurs naturally in all parts of the body and that the body needs to function normally. It is present in cell walls or membranes everywhere in the body, including the brain, nerves, muscle, skin, liver, intestines, and heart. The body uses cholesterol to produce many hormones, vitamin D, and the bile acids that help to digest fat. It takes only a small amount of cholesterol in the blood to meet these needs.  However, if you have too much cholesterol in the bloodstream, it can lead to atherosclerosis, a condition in which fat and cholesterol are deposited in the walls of the arteries in many parts of the body, including the coronary arteries feeding the heart. In time, narrowing of the coronary arteries by atherosclerosis can produce the signs and symptoms of CHD, including angina and heart attack.

Lipoproteins

Cholesterol travels in the blood in packages called lipoproteins. Just like oil and water, cholesterol, which is fatty, and blood, which is watery, do not mix. In order to be able to travel in the bloodstream, the cholesterol made in the liver is combined with protein, making a lipoprotein. This lipoprotein then carries the cholesterol through the bloodstream. There are specific kinds of lipoproteins that contain cholesterol in the blood, and each affects your heart disease risk in a different way.

Low density lipoproteins (LDLs): the “bad” cholesterol. LDLs carry most of the cholesterol in the blood, and the cholesterol from LDLs is the main source of damaging buildup and blockage in the arteries. Thus, the more LDL-cholesterol you have in your blood, the greater the risk of CHD. If one has CHD and their LDL is higher than 100 mg/dL, their cholesterol may be too high.

High density lipoproteins (HDLs): the “good” cholesterol. HDLs carry cholesterol in the blood from other parts of the body back to the liver, which leads to its removal from the body. So HDLs help keep cholesterol from building up in the walls of the arteries. If the level of HDL-cholesterol is below 35 mg/dL, one is at substantially higher risk for CHD.  The higher the HDL-cholesterol, the better. The average HDL-cholesterol for men is about 45 mg/dL, and for women it is about 55 mg/dL.

Triglycerides: a form of fat carried through the bloodstream. Most of the body’s fat is in the form of triglycerides stored in fat tissue. Only a small portion of triglycerides is found in the bloodstream. High blood triglyceride levels alone do not cause atherosclerosis. But lipoproteins that are rich in triglycerides also contain cholesterol, which causes atherosclerosis in some people with high triglycerides. So high triglycerides may be a sign of a lipoprotein problem that contributes to CHD.

What Makes Blood Cholesterol High or Low?

Blood cholesterol level is affected not only by what a person eats but also by how quickly their body makes LDL-cholesterol and disposes of it.  In fact, the body makes all the cholesterol it needs, and it is not necessary to take in additional cholesterol from the foods eaten.  Patients with CHD typically have too much LDL-cholesterol in their blood. Many factors help determine whether a LDL-cholesterol level is high or low. The following factors are the most important:

Heredity - Genes influence how high  LDL-cholesterol is by affecting how fast LDL is made and removed from the blood. One specific form of inherited high cholesterol that affects 1 in 500 people is familial hypercholesterolemia, which often leads to early CHD. But even if you a person has a specific genetic form of high cholesterol, genes play a role in influencing LDL-cholesterol levels.

What you eat - Two main nutrients in foods make the LDL cholesterol level go up: saturated fat, a type of fat found mostly in foods that come from animals; and cholesterol, which comes only from animal products. Saturated fat raises the LDL-cholesterol level more than anything else in the diet. Eating too much saturated fat and cholesterol is the main reason for high levels of cholesterol and a high rate of heart attacks in the United States. Reducing the amount of saturated fat and cholesterol  is a very important step in reducing blood cholesterol levels.

Weight - Excess weight tends to increase  LDL cholesterol levels. If a person is overweight and has a high LDL-cholesterol level, losing weight may help them lower it. Weight loss also helps to lower triglycerides and raise HDL

Physical activity/exercise - Regular physical activity may lower LDL-cholesterol and raise HDL-cholesterol levels.

Age and sex - Before menopause, women usually have total cholesterol levels that are lower than those of men the same age. As women and men get older, their blood cholesterol levels rise until about 60 to 65 years of age. In women, menopause often causes an increase in their LDL-cholesterol and a decrease in their HDL-cholesterol level, and after the age of 50, women often have higher total cholesterol levels than men of the same age. Some women may benefit from hormone replacement therapy (also called estrogen replacement therapy) after menopause, because estrogen lowers LDL and raises HDL.

Alcohol - Alcohol intake increases HDL-cholesterol but does not lower LDL-cholesterol. Doctors don’t know for certain whether alcohol also reduces the risk of CHD. Drinking too much alcohol can damage the liver and heart muscle, lead to high blood pressure, and raise triglycerides. Because of the risks, alcoholic beverages should not be used as a way to prevent CHD.

Stress - Stress over the long term has been shown in several studies to raise blood cholesterol levels. One way that stress may do this is by affecting habits. For example, when some people are under stress, they console themselves by eating fatty foods. The saturated fat and cholesterol in these foods contribute to higher levels of blood cholesterol.

Unstable Plaque

Cholesterol is a major ingredient of the plaque that builds up in the coronary arteries and causes CHD, so it is important to understand how plaques develop.  Excess cholesterol is deposited in the artery walls as it travels through the bloodstream. Then, special cells in the artery wall gobble up this excess cholesterol, creating a “bump” in the artery wall. This cholesterol-rich “bump” then is covered by a scar that produces a hard coat or shell over the cholesterol and cell mixture. It is this collection of cholesterol covered by a scar that is called plaque.

The plaque buildup narrows the space in the coronary arteries through which blood can flow, decreasing the supply of oxygen and nutrients to the heart. If not enough oxygen-carrying blood can pass through the narrowed arteries to reach the heart muscle, the heart may respond with a pain called angina. The pain usually happens with exercise when the heart needs more oxygen. It is typically felt in the chest or sometimes in other places like the left arm and shoulder. However, this same inadequate blood supply may cause no symptoms.

Plaques come in various sizes and shapes. Throughout the coronary arteries many small plaques build themselves into the walls of the arteries, blocking less than half of the artery opening. These small plaques are often invisible on many of the tests doctors use to identify coronary heart disease. It used to be thought that the most dangerous plaques and the ones most likely to cause total blockage of coronary arteries were the largest ones. The largest plaques are in fact the ones most likely to cause angina. However, small plaques that are full of cholesterol but not completely covered by scar are now thought to be very unstable and more likely to rupture or burst, releasing their cholesterol contents into the bloodstream.

When this happens, it triggers blood clotting inside the artery. If the blood clot totally blocks the artery, it stops blood flow and a heart attack occurs. The muscle on the far side of the blood clot does not get enough oxygen and begins to die. The damage can be permanent. Lowering blood cholesterol levels can slow, stop, or even reverse the buildup of plaque. Cholesterol lowering can reduce the risk of a heart attack by lowering the cholesterol content in unstable plaques to make them more stable and less prone to rupture. This is why lowering your LDL-cholesterol is such an important way to reduce the risk for having a heart attack. Even in people who have had one heart attack, the chances of having future attacks can be substantially reduced by cholesterol lowering.

The Benefits of Cholesterol Lowering

A 1994 study called the Scandinavian Simvastatin Survival Study (also called 4S) found that lowering cholesterol can prevent heart attacks and reduce death in men and women who already have heart disease and high cholesterol.

For over 5 years, more than 4,400 patients with heart disease and total cholesterol levels of 213 mg/dL to 310 mg/dL were given either a cholesterol lowering drug or a placebo (a dummy pill that looks exactly like the medication). The drug they were given is known as a statin (see page 20), and it reduced total cholesterol levels by 25 percent and LDL-cholesterol levels by 35 percent.

The study found that in those receiving statin, deaths from heart disease were reduced by 42 percent, the chance of having a nonfatal heart attack was reduced by 37 percent, and the need for bypass surgery or angioplasty was reduced by 37 percent. A very important finding is that deaths from causes other than cardiovascular disease were not increased, and so the 42 percent reduction in heart disease deaths resulted in a 30 percent drop in overall deaths from all causes.

The 4S researchers say that the following benefits could be expected if doctors were to treat their heart disease patients for the same 5-year period and lower cholesterol to the same extent. For every 1,000 patients:  40 people would be saved out of the 90 who would otherwise die from heart disease.  70 of the expected 210 nonfatal heart attacks would be avoided.  Heart procedures such as bypass surgery would be avoided in 60 of the 210 patients who would be expected to need these procedures.

In 1996 the results of the Cholesterol and Recurrent Events (CARE) Study also showed the benefits of cholesterol lowering in CHD patients. This study reported that even in patients with seemingly normal cholesterol levels (average of 209 mg/dL), cholesterol lowering with a statin drug lowered the risk of having another heart attack or dying by 24 percent. These patients were also less likely to need bypass surgery (26 percent reduction) or angioplasty (22 percent reduction) during the study.

Women benefited even more than men, reducing their risk of having another heart attack by 45 percent. The CARE researchers estimate that treatment of 1,000 patients similar to those in CARE would result in 153 fewer heart attacks and deaths from heart disease. If the patients were over 60, there would be 214 fewer, and if they were all women, there would be 248 fewer. These studies along with many others support the need to lower cholesterol levels in CHD patients. If you lower your cholesterol, you too can see benefits like those in 4S and CARE.

Persons with CHD Have a Lower Goal Cholesterol Level

For the general population, a level of LDL-cholesterol below 130 mg/dL is called desirable.  For individuals that have CHD, their goal is lower: They should reduce their LDL-cholesterol to about 100 mg/dL or less. This is because patients with CHD, even if they have relatively low cholesterol levels (say an LDL-cholesterol of 120 mg/dL), have shown that they are susceptible to developing CHD at that level. A recent study has reaffirmed the benefit of lowering LDL-cholesterol levels in CHD patients to 100 mg/dL or less.

Risk Factors for Coronary Heart Disease

In addition to a high total and LDL-cholesterol level and a low HDL-cholesterol level, other factors also increase the chance of having CHD complications. They are:

  • High total cholesterol and high LDL-cholesterol
  • Low HDL-cholesterol and high LDL-cholesterol
  • Cigarette smoking
  • High blood pressure
  • Diabetes
  • Obesity/overweight
  • Physical inactivity

Smoking: Cigarette smoking is a strong risk factor for CHD. Stopping smoking reduces the risk for CHD and stroke, beginning with the first year after stopping smoking. It also reduces the chances of getting lung cancer and other cancers and chronic lung disease. Changing to low-tar or low-nicotine cigarettes does not reduce the risk for CHD. 

High blood pressure: High blood pressure (or hypertension) is associated with increased rates of CHD, as well as stroke and kidney failure. Treatment of hypertension reduces the risk for all these complications. 

Diabetes: Diabetes, whether insulin dependent or non-insulin dependent, increases the risk for CHD. In men, diabetes increases risk for CHD complications by about three times, and the increase in risk may be even greater for women.

Obesity: Obesity or overweight increases the risk for CHD in men and women. If a person is overweight, losing weight can improve other risk factors including diabetes, high blood pressure, and cholesterol, making weight loss very important in the treatment of CHD.

Physical inactivity: Physical inactivity can increase the risk for CHD. Regular physical activity can reduce LDL cholesterol, triglycerides, high blood pressure, and weight while raising HDL-cholesterol and improving the fitness of the heart and lungs. Regular physical activity is recommended to reduce the risk of future CHD complications.

Diet:  A diet lower in saturated fat and cholesterol, than the average American diet, is a healthy way for the whole family to eat (except infants under 2 years who need more calories from fat). 

Recommended Diet for those with CHD

  • Less than 7 percent of the day’s total calories should be from saturated fat.
  • 30 percent or less of the day’s total calories should be from fat.
  • Less than 200 milligrams of total dietary cholesterol a day.
  • Just enough calories to achieve and maintain a healthy weight.

The recommendations for saturated fat and total fat are based on a percentage of the total calories a person eats; the actual amount a person can eat daily will vary depending on how many total calories they eat.

General ways to lower blood cholesterol through diet

Choosing foods low in saturated fat.

All foods that contain fat have different mixtures of saturated and unsaturated fats. Saturated fat raises blood cholesterol levels more than anything else.  It is found in greatest amounts in foods from animals, such as fatty cuts of meat, poultry with the skin, whole-milk dairy products, and lard, and in tropical oils like coconut, palm kernel, and palm oils. Most other vegetable oils are low in saturated fats. The best way to reduce blood cholesterol levels is to choose foods low in saturated fat. One way to do this is by choosing foods such as fruit, vegetables, and whole grain foods, which are naturally low in fat and high in starch and fiber. 

Choosing foods low in total fat

Since many foods high in total fat are also high in saturated fat, eating foods low in total fat will help. Any type of fat is a rich source of calories, so eating foods low in fat should also help. When eating fat, a person should substitute unsaturated fat for saturated fat. Unsaturated fat can be either monounsaturated or polyunsaturated. Examples of foods high in monounsaturated fat are olive and canola oils. Those high in polyunsaturated fats are safflower, sunflower, corn, and soybean oils.  Food labels are the best guide to how much total fat, saturated fat, and unsaturated fat and how many calories are in the product.

Choosing foods low in cholesterol: 

Dietary cholesterol also can raise blood cholesterol levels, although usually not as much as saturated fat. So it is important to choose foods low in dietary cholesterol. Dietary cholesterol is found only in foods that come from animals.  Many of these foods also are high in saturated fat. Foods from plant sources do not have cholesterol but can contain saturated fat.

Choosing foods high in starch and fiber:

Foods high in starch and fiber are excellent substitutes for foods high in saturated fat. These foods—breads, cereals, pasta, grains, fruits, and vegetables—are low in saturated fat and cholesterol, unless fat is added in their preparation. They are also usually lower in calories than foods that are high in fat. Foods high in starch and fiber are also good sources of vitamins and minerals.

A word about sodium

  • If a person has high blood pressure as well as high blood cholesterol (and many people do), a doctor may tell the person to cut down on sodium or salt.  Sodium intake should be limited to 2,400 milligrams a day.

Practical Ways to Change a Diet 

Here are some tips on how to choose foods.

Cut back on saturated fats, choose:

  • Poultry, fish, and lean cuts of meat. Remove the skin from chicken and trim the fat from meat before cooking.
  • Skim or 1 percent milk instead of 2 percent or whole milk.
  • Cheeses with no more than 3 grams of fat per ounce (these include low-fat cottage cheese or other low-fat cheeses).
  • Cut down on full-fat processed, natural, and hard cheeses (like American, brie, and cheddar).
  • Low-fat or non-fat yogurt, sour cream, and cream cheese instead of the high-fat varieties.
  • Liquid vegetable oils that are high in unsaturated fat (these include canola, corn, olive, and safflower oil).
  • Margarine made with unsaturated liquid vegetable oil as the first ingredient rather than hydrogenated or partially hydrogenated oil. Choose tub or liquid margarine or vegetable oil spreads. The softer the margarine, the more unsaturated it will be.
  • Fewer commercially prepared and processed foods made with saturated or hydrogenated fats or oils (like cakes, cookies, and crackers).
  • Foods high in starch and fiber such as whole wheat breads and cereals instead of foods high in saturated fats.

Cutting back on saturated fat helps to control dietary cholesterol as well, because cholesterol and saturated fat are often, but not always, found together in the same foods.

To include more foods high in starch and fiber:

Eat more vegetables and fruits. It is recommended that Americans eat five servings of fruits and vegetables every day. They are low in saturated fat and total fat and have no cholesterol. Fruits and vegetables are good sources of starch, fiber, vitamins, and minerals and are low in sodium. They are also low in calories (which helps with weight control) except for avocados and olives, which are high in both fat and calories. Many fruits and vegetables are also high in vitamin C, vitamin E, and beta-carotene— so-called “antioxidants.” A diet high in these fruits and vegetables may also help to lower risk for heart disease. So fruits and vegetables are great substitutes for foods high in saturated fat and cholesterol.  Whole grain breads and cereals, pasta, rice, and dry peas and beans are necessary. Cholesterol Continuing Education Online for Nurses, Nurse CEUs

Cook the low-fat way:

Bake, broil, microwave, poach, or roast instead of breading and frying.  When roasting, place the meat on a rack so the fat can drip away.

Two additional points to remember are:

  • Strictly limit organ meat (such as liver, brain, and kidney).
  • Eat a total of two or fewer egg yolks a week (as whole eggs or in prepared foods). Substitute two egg whites for each whole egg in recipes, or using an egg substitute.

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