Cholesterol is a serious heart disease risk factor. Although the risk rises with the level of cholesterol, some people with relatively low values experience problems with atherosclerosis. Cholesterol is a fatlike substance found in all human and animal tissues but not in plants. We ingest cholesterol in foods from animals (e.g., meat, eggs, fish, poultry, and dairy products), or we can synthesize it in the body. If you don’t eat much cholesterol, the body will make all it needs from other fats. The blood transports cholesterol in low- or high-density lipo-protein packages.
The ideal total cholesterol level is below 150 milligrams. Values from 150 to 200 should respond to a moderate reduction of saturated and hydrogenated fats in the diet. Levels from 200 to 240 call for a concentrated effort to reduce these atherogenic fats and take additional dietary measures, including increasing intake of bran and other natural foods to reduce cholesterol. Cholesterol levels that remain above 240 after dietary, exercise, and weight-loss interventions may require drug therapy, especially if other risk factors are present. Fortunately, cholesterol drugs have been proved successful at lowering levels and the incidence of heart disease. Consult your physician for details.
Low-density lipoprotein cholesterol (LDL) is the dangerous version that finds its way into the lining of the coronary arteries. It can combine with oxygen and enhance the development of plaques in arteries. High-density lipoprotein cholesterol (HDL) acts like a transport system that picks up excess cholesterol and delivers it to the liver for reprocessing or removal. Thus, higher HDL levels are protective, with a one-milligram increase associated with a 2 to 3 percent reduction in CAD. Conversely, low values are an independent risk factor. So you can have a low total cholesterol level and still have some risk if your HDL is low. You should know all three numbers (total cholesterol, LDL, and HDL), as well as your cholesterol to HDL ratio.
Another way to assess your risk is to calculate your total cholesterol to HDL ratio. A ratio under 4 (e.g., 200 divided by 50) is associated with a low risk of heart disease, whereas a ratio over 6 (e.g., 240 divided by 40) is not. All adults should be tested every 5 years unless values are borderline or high, a circumstance that calls for annual testing and treatment.
Recent research has identified two additional tests to help determine one’s risk of heart disease:
- Homocysteine is often elevated in the blood of those at high risk for heart prob¬lems. A blood test will show if a problem exists. If it does, the solution is simple: an increase in foods containing the B vitamin folate (or a folate supplement). Folate is also important for pregnant women or those planning to become pregnant.
- C-reactive protein (C-RP) is a sign of inflammatory activity that is associated with an increased risk of a heart attack (Ridker et al. 2000). C-RP may influence apoptosis or fragmentation of human coronary vascular smooth muscle cells, a key event in the development of atherosclerotic lesions and the vulnerability of plaque to rupture (Blaschke et al. 2004). But because C-RP is also associated with chronic infections and arthritis, it is viewed as a relatively moderate predictor of CAD (Danesh et al. 2004). Recent studies indicate that cholesterol-lowering statin drugs may also lower C-RP, and that those with lower C-RP levels have a greater reduction in coronary risk (Nissen et al. 2005). A blood test can determine the level. Efforts to reduce the risk may include daily intake of an aspirin, vitamin E, an alcoholic beverage, weight loss, statin therapy, and, of course, physical activity.
In case you were wondering about triglyceride levels, some say that they do not provide clinically relevant information about CAD risk beyond that obtained with measures of cholesterol, LDL, and HDL (Avins and Neuhaus 2000). But elevated triglycerides may be a risk factor for CAD when cholesterol levels are low. High triglycerides are often associated with low HDL and blood clotting, and may lead to enlargement of the liver. Normal fasted levels should be below 150 milligrams per 100 milliliters. We’ll say more about the blood lipids, cholesterol, and triglycerides in later chapters.
If your risk of heart disease is high, you should know that new information is available that you can use to improve your health. The National Cholesterol Education Program has formulated new guidelines for LDL cholesterol. High-risk persons (based on risk factors) should aim to get LDL cholesterol below 70, well below the previous goal of 100 milligrams per deciliter. Studies indicate that the lower the LDL cholesterol level, the better. Achieving this level will probably require use of prescription drugs (Grundy et al. 2004).