Unfavorable Cholesterol Levels - Recognizing And Reducing Risk Factors: Heart Disease

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Unfavorable cholesterol levels

About one in five Americans has high cholesterol. Improving your cholesterol profile can have a substantial impact on health. If sustained, a 10% reduction in total cholesterol can produce a 20%–30% reduction in the risk for heart attack. The National Cholesterol Education Program (NCEP), part of the National Institutes of Health, has created guidelines that provide an easy way to set your cholesterol goal based on your risk for heart disease, and then to take steps to achieve your goal. The NCEP guidelines are periodically updated on the basis of new evidence. The guidelines published in July 2004 are summarized in Table 1.

Although total cholesterol levels are important, it's even more important to look at levels of different types of cholesterol, particularly LDL and HDL. That is why the NCEP recommends that everyone age 20 and older undergo a fasting lipid profile test (also termed a full lipid profile or lipoprotein analysis) every five years. This test not only determines total cholesterol, but also measures LDL, HDL, and triglyceride levels.

Total cholesterol

This number is the sum of cholesterol carried in all cholesterol-bearing particles in the blood, including HDL, LDL, and VLDL. Although the total cholesterol level closely parallels the LDL level in most people, there are enough exceptions to that rule to make it useful to test separately for LDL, HDL, and triglycerides. The NCEP guidelines advise aiming for a total cholesterol level below 200 mg/dL.

LDL

No specific cholesterol level guarantees that you will, or won't, develop heart disease. However, LDL is clearly the most significant of the blood lipids in terms of raising your risk for heart disease, so lowering elevated LDL should be the primary target of therapy. In making its July 2004 recommendations, the NCEP cited data from clinical studies that indicate that, for every 1% reduction in LDL levels, there is a corresponding 1% decrease in the chance of being stricken with a heart attack, stroke, or some other type of cardiac event. This is significant given that the proper combination of lifestyle changes and heart medications can help lower LDL levels by 30%–40% in many people at risk for heart disease (and in some people, lower it even further), creating a corresponding drop in cardiac events.

So how low do you go? One series of studies changed the thinking in this area. In a nutshell, if you have had a heart attack or are at very high risk of having one, the answer is lower than before, and probably as low as possible (see "The lower the cholesterol, the better," below). Your particular LDL target depends on your cardiovascular health and your odds of having a heart attack in the next 10 years (see Table 6 or 7 to calculate your own heart attack risk). Levels range from below 70 mg/dL or lower for those at very high risk to less than 160 mg/dL for people at lowest overall risk.

You can lower LDL levels by reducing the amount of saturated fat, trans fat, and cholesterol in your diet; eating more complex carbohydrates, such as fruits and vegetables; eating more fiber; reducing body fat; and exercising regularly (see "Lifestyle changes to protect yourself"). When these good habits aren't sufficient to reach your cholesterol goal, cholesterol-lowering medications are recommended.

HDL

The more HDL in your bloodstream, the lower your chances of having a heart attack. Studies from the Framingham Heart Study and elsewhere suggest that every one-point rise in HDL results in a 2%–3% reduction in the risk for heart attack. The NCEP guidelines consider levels of 60 mg/dL or above protective against heart disease, while levels of less than 40 mg/dL are regarded as too low and increase your risk. However, some clinicians use the ratio of total cholesterol to HDL cholesterol to help identify people who need cholesterol-lowering therapy. The less HDL you have relative to total cholesterol, the greater your risk for heart disease. To boost your HDL, your best bets are to lose weight, eat well, engage in more physical activity, and stop smoking.

Triglycerides

The main form of stored fat — both in the food we eat and in the body's adipose (fat) tissue — is triglycerides. The chylomicron, the largest and least dense of the lipoprotein particles, carries most of the triglycerides in the bloodstream. In general, triglyceride levels have less of an impact on heart disease risk than LDL or HDL levels. However, when triglyceride levels are very high, risk for heart disease does increase. Often people with low HDL cholesterol levels also have high triglycerides, and this combination seems an especially important predictor of heart disease risk.

The NCEP guidelines define normal triglyceride levels as below 150 mg/dL. High triglyceride levels can result from obesity, physical inactivity, cigarette smoking, alcohol abuse, uncontrolled diabetes, and even certain medications, as well as some genetic disorders. Often, triglycerides can be lowered using the same steps that help bring down LDL cholesterol: eating a healthier diet, exercising more often, losing weight, and, if necessary, taking medications to lower LDL, triglycerides, or both.

Last updated:	May 03, 2007