What Is Cholesterol?

Cholesterol is a waxy substance present in blood. It is white, crystalline, odorless and tasteless. Cholesterol is an essential substance your body uses to form cell membranes, some hormones and other tissues. It enables the body to synthesize bile acids and vitamin E.

Although cholesterol is made by several organs of the body, the predominant one is the liver. Cholesterol also is ingested in some of the foods you eat, including meat, poultry, fish, seafood, eggs and dairy products.

There are two dominant types of cholesterol. Because cholesterol cannot dissolve in blood, it must be transported to and from the cells by special carriers known as lipoproteins. Two of the types of cholesterol are known by their respective lipoproteins. Low-density lipoprotein transports "LDL cholesterol," and high-density lipoprotein transports "HDL cholesterol."

Low-density lipoprotein carries the so-called "bad" cholesterol away from the liver and throughout the bloodstream to various tissues and cells. It can deposit the cholesterol on the inner walls of your coronary arteries. These arteries bring blood and oxygen to your heart.

The cholesterol on the arterial walls can combine with other substances to form plaques. This is called atherosclerosis, or hardening of the arteries. When this happens, blood flow becomes restricted. If blood flow is completely blocked, the heart does not get the oxygen it needs and the muscle becomes permanently damaged. This is called a myocardial infarction, or heart attack. When the brain is similarly starved for oxygen, the result is a stroke.

High-density lipoprotein carries the "good" cholesterol. This cholesterol helps your body get rid of the bad cholesterol in your blood. High-density lipoproteins possibly transport excess or unused cholesterol from the tissues back to the liver, where it is broken down to bile acids and then excreted. Some experts believe HDL cholesterol removes excess LDL cholesterol from atherosclerotic plaques, thereby retarding their growth.

How Can I Find Out My Cholesterol Levels?

Your physician can measure your LDL cholesterol, HDL cholesterol and total cholesterol by analyzing your blood.

As ongoing scientific studies provide new information about cholesterol and coronary artery disease, the recommended levels of total cholesterol and LDL cholesterol descend.

Whether your cholesterol levels are desirable depends on the presence or absence of certain factors. For example, the recommended levels for a person who has cardiovascular disease differs from those recommended for a healthy individual.

The following figures are the National Heart, Lung and Blood Institute recommendations for healthy individuals (as of 1996):

Desirable total blood (serum) cholesterol is less than 200 milligrams per deciliter (mg/dl). Borderline high is 200-239 mg/dl. A high level of cholesterol in the blood is 240 mg/dl or greater.

LDL-cholesterol level is a better predictor of heart attack risk than total blood cholesterol. A desirable level is 130 mg/dl or lower. Borderline is 130-159 mg/dl. High is 160 mg/dl or greater.

In looking at your HDL-cholesterol level, note that the average man falls between 40 and 50 mg/dl and the average woman has between 50 and 60 mg/dl. Less than 35 mg/dl is low.

How Often Should I Have My Cholesterol Levels Tested?

According to the American Heart Association, if your total cholesterol is less than 200 mg/dl, have it measured again within five years. You should still eat intelligently, exercise and manage the stress levels in your life.

If your total cholesterol level is between 200 and 239, your HDL is more than 35 mg/dl and you have fewer than two risk factors, you should have your cholesterol checked in one to two years.

If your cholesterol is greater than 240, your doctor probably will order additional diagnostic tests.

What Can I Do to Lower My Cholesterol?

The primary way to lower total cholesterol is through healthful eating. If you stick to a low-fat diet you should obtain the desired results. You can start by using the food pyramid to plan your daily menu. Make most of your selections from the bottom of the pyramid and fewer selections as you work your way up.

What Is a Serving of Bread, Rice, Cereal and Pasta?

A serving is one slice of bread; one-half of a bagel, bun or English muffin; 1 ounce (½ to 1 cup), ready-to-eat cereal; ½ cup cooked cereal, rice or pasta. Try corn tortillas, high-fiber cereals, kasha, millet, couscous, bulgur, air-popped popcorn and unsalted pretzels. Cut down on donuts, muffins and pastries.

What Is a Serving of Fruit?

A serving of fruit is one medium-sized whole fresh fruit; 1 cup of berries or a medium slice of melon; ½ cup chopped, cooked or canned fruit; ¾ cup fruit juice. When you buy canned fruit, choose fruit in its own juices instead of fruit in heavy syrup.

Avoid coconut. Count olives and avocados as fats.

What Is a Serving of Vegetables?

One serving is 1 cup of raw vegetables, or ½ cup cooked vegetables. A serving of vegetable juice is ¾ cup.

Starchy vegetables belong in the bread and pasta group. These vegetables include potatoes, corn, lima beans, green peas, winter squash, yams and sweet potatoes.

What Is a Serving of Fish, Meat, Chicken or Beans?

One serving is 2 to 3 ounces cooked fish, poultry or lean meat; ½ cup cooked dry beans; ¼ cup tofu or tempeh; one whole egg or two egg whites; 2 tablespoons peanut butter, nuts or seeds.

Eat as much as 6 ounces (cooked) per day of meat, fish or poultry. Instead of using meat as the main ingredient, try adding it as a condiment in stews or casseroles. When you buy meat or poultry, choose the leanest cuts you can find.

Consume no more than four egg yolks each week.

What Is a Serving of Dairy Products?

A serving is one cup of milk (cow's, soy or rice); 1 cup of yogurt; ½ cup of cottage cheese; 1.5 ounces of natural or soy cheese; or 2 ounces of processed cheese.

Use low-fat or nonfat dairy products.

What Is a Serving of Fats, Oils or Sweets?

Limit added fat to no more than 1 to 2 tablespoons a day. Limit added sugar to no more than 2 to 6 teaspoons a day.

Use canola, safflower, corn, sesame, soybean, sunflower and olive oil. Avoid coconut oil, palm oil or hydrogenated fats. Try nonfat salad dressings.

Is All Dietary Fat Alike?

There are three kinds of fats in foods: saturated, polyunsaturated and monounsaturated fats. Only saturated fatty acids can raise your blood cholesterol. You will find saturated fatty acids in beef, veal, lamb, pork, lard, poultry fat, butter, cream, milk, cheese, coconut oil, palm oil, palm kernel oil and cocoa butter.

How Much Dietary Cholesterol and Fat Should I Consume Daily?

The American Heart Association makes the following recommendations for daily cholesterol consumption:

1. Limit your cholesterol intake to an average of no more than 300 milligrams per day.
2. Limit your saturated fatty acid intake to less than 10 percent of total calories each day.
3. Limit polyunsaturated fatty acids to 10 percent of total calories.
4. Limit monounsaturated fatty acids to about 10 percent to 15 percent of calories.
5. Eat no more than four egg yolks per week, including those used in cooking.
6. Eat no more than 6 ounces of cooked lean meat, poultry, fish or seafood each day.

What Should I Look for on Food Labels?

Food labels will tell you the fat content of the foods you eat. Look for the box labeled "Nutrition Facts." In this box, you will find numbers for total fat, saturated fat and cholesterol. If you are also trying to lower your high blood pressure, check the sodium content of the product.

Be sure to check the serving size. You may be surprised at how small it is.

Then look at the list of ingredients. Limit your intake of products that list any fat or oil first, or that list many fat and oil ingredients.

Sometimes a label will say that the product is "light" or "low fat." Although these terms and others may sound vague, they actually mean specific things. The National Heart, Lung and Blood Institute of the National Institutes of Health elucidates the meanings:

What Else Can I Do to Lower My Cholesterol?