Cholesterol is a fatty substance (a lipid) that is an important part of the outer lining (membrane) of cells in the body of animals. Cholesterol is also found in the blood circulation of humans. The cholesterol in a person's blood originates from two major sources; dietary intake and liver production. Dietary cholesterol comes mainly from meat, poultry, fish, and dairy products. Organ meats, such as liver, are especially high in cholesterol content, while foods of plant origin contain no cholesterol. There are two types of cholesterol: LDL cholesterol is called "bad" cholesterol, because elevated levels of LDL cholesterol are associated with an increased risk of coronary heart disease; HDL cholesterol is called the "good cholesterol" because HDL cholesterol particles prevent atherosclerosis by extracting cholesterol from the artery walls and disposing of them through the liver.
Measuring Cholesterol Levels
A blood test to check cholesterol levels — called a lipid panel or lipid profile — typically reports:
-
Total cholesterol
-
HDL cholesterol
-
LDL cholesterol
-
Triglycerides, a type of fat often increased by sweets and alcohol
For the most accurate measurements, don't eat or drink anything (other than water) for nine to 12 hours before the blood sample is taken. Cholesterol levels are measured in milligrams (mg) of cholesterol per deciliter (dL) of blood.
Healthy Cholesterol Levels
General guidelines for assessing cholesterol levels, issued by the American Heart Association (the leading US heart organization), recommend the following healthy parameters.
Table 1. Total Cholesterol
| Cholesterol Level | Health Category |
| Less than 200 mg/dL | Desirable |
| 200-239 mg/dL | Borderline high |
| 240 mg/dL | High |
Borderline High Cholesterol Level Without Additional Risk Factors
If your total cholesterol level is between 200-239 md/dl, you have "borderline-high" blood cholesterol, with an increased risk for heart disease compared to people with lower levels. If so, and if you have no other risk factors (eg. family history of coronary heart disease before the age of 55, elevated blood pressure, tobacco smoking, diabetes, vascular disease, obesity, male gender), you should not require specific medical attention. However, you should follow a cholesterol-lowering diet to normalize your level and thereby reduce your risk of atherosclerosis.
High Cholesterol Level or Borderline High With Additional Risk Factors
If you have high total cholesterol or borderline-high with two other risk factors for coronary heart disease, you need special medical attention. To begin with, your doctor will measure your low density lipoprotein (LDL) cholesterol level - as LDL levels more accurately reflects your risk for coronary heart disease than total cholesterol level alone. LDL levels of 130 mg/dl or greater increase your risk for developing coronary heart disease. After evaluating your LDL level and assessing your other risk factors, your doctor will determine an appropriate treatment program to reduce both your total and LDL cholesterol level.
Table 2. LDL Cholesterol
| LDL Cholesterol Level | Health Category |
| Less than 100 mg/dL | Optimal |
| 100-129 mg/dL | Near optimal |
| 130-159 mg/dL | Borderline high |
| 160-189 mg/dL | High |
| 190 mg/dL | Very high |
HDL Cholesterol Levels
If the HDL cholesterol levels (the good guy) falls to 40 mg/dL or below, this is considered low and may increase the risk of heart disease.