Cholesterol is a waxy, fatlike substance found in tissue and in the blood. Our bodies manufacture about 80 percent of our cholesterol supply, and we get the rest by eating certain foods, especially saturated fats. Cholesterol that is found in food is called dietary cholesterol; the type found in your blood-stream is referred to as blood or serum cholesterol. Many factors affect blood cholesterol. The cholesterol that circulates in your body comes from both the cholesterol your body produces and from the foods you eat. Even though you often see cholesterol listed with dietary fat, cholesterol is not the same as fat.
When triggered by sunlight, cholesterol in your skin has the ability to convert to vitamin D, which is an essential vitamin necessary for building bone.
Cholesterol differs from fat in that it possesses a different type of structure and performs separate functions in the body. Cholesterol also differs from fat in that it is not broken down in the body and therefore does not provide energy and calories. Eating too much fat can cause you to gain weight, whereas cholesterol cannot.
Cholesterol is essential for maintaining healthy cell function. The body requires it to insulate nerves, create cell membranes, and produce certain hormones such as estrogen and testosterone. It is part of every body cell and is also a component of bile, which helps the body to digest and absorb needed fat. In moderation, cholesterol is essential to many bodily functions. However, your body makes plenty of cholesterol, and most dietary cholesterol you consume is considered to be excess.
Computing Your Cholesterol
It is important to have your blood cholesterol checked regularly because symptoms of high cholesterol are not always obvious. The American Heart Association recommends that all adults aged twenty or older have a fasting lipid profile (total cholesterol, LDL cholesterol, HDL cholesterol, and triglyceride) once every five years.
Cholesterol is measured through blood analysis and is best tested when the person fasts for at least twelve hours prior to drawing blood. The sample is analyzed for total cholesterol and, if the need exists, for LDLs and HDLs. Cholesterol is measured in milligrams per deciliter (mg/dL).
Triglycerides don't get as much attention as cholesterol, but they are also linked to heart disease. If you have several risk factors for heart disease, your doctor will probably check your triglyceride levels along with your cholesterol. Triglycerides are the main form of fat in foods and in the blood. Your triglyceride level will fall into one of these categories:
Normal: less than 150 mg/dL
Borderline to high: 150–199 mg/dL
High: 200–499 mg/dL
Very high: greater than 500 mg/dL
Because of their roles in metabolism, triglyceride levels are inversely related to HDL-cholesterol levels. When a person has a high triglyceride level, the HDL-cholesterol levels are usually low.
Total Cholesterol Levels
It is important to ask your doctor for a total lipoprotein profile so you are aware of not only your total cholesterol but of each component of your cholesterol. You may have a total cholesterol level that is desirable, but that doesn't mean your HDL and LDL levels are in line. Your total cholesterol level will fall into one of three categories:
Desirable: less than 200 mg/dL
Borderline high risk: 200–239 mg/dL
High risk: 240 mg/dL and over
If you fall in the desirable range, your risk for heart attack is relatively low. However, it is still smart to get plenty of physical activity and to follow a healthy diet low in cholesterol and saturated fat, and to maintain a healthy weight.
If you fall within the borderline high-risk range, you have at least twice the risk of a heart attack compared with someone who is in the desirable range. If you are in this range, your HDL is less than 40 mg/dL, and you don't have other risk factors for heart disease, you should have your total cholesterol and HDL rechecked in one to two years. You should also lower your intake of foods high in saturated fat and cholesterol to help reduce your cholesterol level to below 200. Your doctor may order another blood test to measure your LDL cholesterol. Even if your total cholesterol puts you in the borderline high-risk range, you may not be at high risk for a heart attack. Some people, such as women before menopause, and young, active men with no other risk factors, can have high HDL cholesterol and desirable LDL levels, so it is best to ask your doctor to interpret your results. Everyone's case is different.
The American Heart Association now encourages Americans to think of their blood cholesterol as a vital sign, similar to blood pressure, for measuring heart health.
If your total cholesterol level is 240 or more, you are definitely at high risk. Your risk of heart attack and, indirectly, of stroke are greater. If you fall in this category, you should ask your doctor for advice. About 20 percent of the U.S. population has what are considered high blood cholesterol levels.
The bottom line is that the less LDL you have, and the more HDL you have, the lower your risk for heart disease. When it comes to trying to lower your LDL, your food choices are key.
Follow your physician's advice after you have had your cholesterol tested.
If you have a cholesterol reading over 240 mg/dL or you have risk factors such as heart disease along with cholesterol readings over 200 mg/dL, your doctor will probably prescribe a cholesterol-lowering medication in combination with a healthy low-fat diet and exercise. Several different types of these medications are on the market today, and your doctor may even prescribe more than one. Your doctor should periodically test your blood cholesterol levels to check on your progress. As with any type of medication that your doctor prescribes, it is essential to follow the recommended dosage and schedule requirements to experience results.