Cholesterol is a soft, fat-like, waxy substance found in the bloodstream and in all your body's cells. It's an important part of a healthy body because it's used for producing cell membranes and some hormones, and serves other needed bodily functions. But too high a level of cholesterol in the blood is a major risk for coronary heart disease, which leads to heart attack. It's also a risk factor for stroke. Hypercholesterolemia is the term for high levels of blood cholesterol.
You get cholesterol in two ways. Your body makes some of it, and the rest comes from cholesterol in animal products that you eat, such as meats, poultry, fish, eggs, butter, cheese and whole milk. Food from plants — like fruits, vegetables and cereals — doesn't have cholesterol. Some foods that don't contain animal products may contain trans-fats, which cause your body to make more cholesterol. Foods with saturated fats also cause the body to make more cholesterol.
Cholesterol and other fats can't dissolve in the blood. They have to be transported to and from the cells by special carriers called lipoproteins. There are two kinds that you need to know about. Low-density lipoprotein, or LDL, is known as the "bad" cholesterol. Too much LDL cholesterol can clog your arteries, increasing your risk of heart attack and stroke. High-density lipoprotein, or HDL, is known as the "good" cholesterol. Your body makes HDL cholesterol for your protection. It carries cholesterol away from your arteries. Studies suggest that high levels of HDL cholesterol reduce your risk of heart attack.
HDL Cholesterol "Good"
About one-third to one-fourth of blood cholesterol is carried by high-density lipoprotein (HDL). HDL cholesterol is known as the "good" cholesterol because a high level of it seems to protect against heart attack. (Low HDL cholesterol levels [less than 40 mg/dL] increase the risk for heart disease.) Medical experts think that HDL tends to carry cholesterol away from the arteries and back to the liver, where it's passed from the body. Some experts believe that HDL removes excess cholesterol from plaque in arteries, thus slowing the buildup.
LDL Cholesterol "Bad"
When too much LDL cholesterol circulates in the blood, it can slowly build up in the inner walls of the arteries that feed the heart and brain. Together with other substances it can form plaque, a thick, hard deposit that can clog those arteries. This condition is known as atherosclerosis. If a clot forms and blocks a narrowed artery, it can cause a heart attack or stroke. The levels of HDL cholesterol and LDL cholesterol in the blood are measured to evaluate the risk of having a heart attack. LDL cholesterol of less than 100 mg/dL is the optimal level. Less than 130 mg/dL is near optimal for most people. A high LDL level (more than 160 mg/dL or 130 mg/dL or above if you have two or more risk factors for cardiovascular disease) reflects an increased risk of heart disease. That's why LDL cholesterol is often called "bad" cholesterol.
NCEP Level Guidelines
The National Heart, Lung and Blood Institute issued the Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) in May, 2001. The ATP III report presents NCEP’s updated clinical guidelines for cholesterol testing and management and describes the following classifications for cholesterol and triglyceride testing:Total Cholesterol:
HDL Cholesterol (good):
- Desirable: Less than 200 mg/dL (<5.17 mmol/L)
- Borderline: 200-239 mg/dL (5.17-6.18 mmol/L)
- High: Equal to or greater than 240 mg/dL (>6.21 mmol/L)
LDL Cholesterol (bad):
- Low: less than 40 mg/dL (<1.03 mmol/L)
- High: equal to or greater than 60 mg/dL (>1.55 mmol/L)
- Optimal: less than 100 mg/dL (<2.59 mmol/L)
- Near optimal/above optimal: 100-129 mg/dL (2.59-3.34 mmol/L)
- Borderline high: 130-159 mg/dL (3.36-4.11 mmol/L)
- High: 160-189 mg/dL (4.14-4.89 mmol/L)
- Very high: equal to or greater than 190 mg/dL (>4.91 mmol/L)
ATP III Final Report
- Normal: Less than 150 mg/dL (<1.69 mol/L)
- Borderline high: 150-199 mg/dL (1.69-2.25 mmol/L)
- High: 200-499 mg/dL (2.26 - 5.64 mmol/L)
- Very high: equal to or greater then 500 mg/dL (> 5.65 mmol/L)
The ATP III identified HDL cholesterol levels below 40 mg/dL (1.03 mmol/L) as associated with increased risk of coronary heart disease (CHD) in men and women. A high HDL cholesterol level greater than or equal to 60 mg/dL (1.55 mmol/L) is protective and decreases CHD risk.