For years, we've heard about two forms of cholesterol—the "bad" low-density lipoprotein (LDL) and the "good" high-density lipoprotein (HDL). Higher levels of HDL cholesterol-50 milligrams per deciliter (mg/dL) or above are considered desirable because this form of cholesterol has long been associated with the cleanup of lipids (blood fats) from the arteries.
The Role of LDL
Even though lipids are generally perceived as harmful, they play an essential role in cellular functions.
Here's how: Cholesterol and triglycerides (a type of blood fat) are transported by lipoproteins (complex particles consisting of proteins and lipids) to the body's tissues, where they reinforce cell membranes and aid in the synthesis of hormones and other substances.
However, once these useful lipids are stripped away from the transporting lipoproteins, the leftover portion is known as low-density lipoprotein (LDL)-and it can be harmful. LDL cholesterol can accumulate in artery walls and initiate changes that can lead to heart disease.*
New thinking: HDL cholesterol readings that appear on blood tests may not always be a good indicator of a person's heart disease risk after all. In fact, some people with lower HDL cholesterol actually can be at lower risk than those with very high HDL numbers.
Why is this so? Most people don't realize that unwanted cholesterol is removed from the arteries through a process known as reverse cholesterol transport.
Cutting-edge research: The HDL that is measured on standard cholesterol tests does not necessarily indicate the efficiency of the reverse transport mechanism, researchers now are discovering. This means that some people with very high HDL, for example, could have inefficient disposal of unwanted cholesterol.
Result: Excess lipids remaining in the arteries and an increased risk for heart disease.
Bottom line: High HDL generally confers protection-but only when it accompanies a robust transport mechanism.
Identifying Heart Disease Risk With Greater Accuracy
Routine cholesterol testing remains the mainstay of heart disease risk assessment, along with consideration of known cardiovascular risk factors, such as smoking, high blood pressure, family history and diet. Combined, these conventional risk factors identify most patients who are at risk for heart and vascular diseases.
*LDL cholesterol levels of 100-129 mg/dL are generally considered optimal for healthy adults...below 100 mg/dl is typically recommended for people at risk for heart disease (due to such factors as smoking and high blood pressure).
Problem: About half of all heart attacks occur in people with so-called normal cholesterol levels.
Solution: There now are additional cholesterol tests that measure different types of LDL and HDL cholesterol, which may identify some people at risk for heart disease who are missed by conventional cholesterol testing and assessment of risk factors. These blood tests, which typically are covered by insurance, may give a more accurate assessment of your heart disease risk, when combined with standard measures.
You may want to ask your doctor about getting advanced tests, such as…
- Lp(a). Lipoprotein (a) is a small cholesterol particle that readily penetrates the artery wall, accelerating plaque formation. Lpa) is associated with increased heart attack risk in most people.
- Markers of abnormal LDL particle size, density or number. Tests measuring these markers can help assess cardiovascular disease risk. For some patients, measurement of apolipoprotein B(another lipoprotein) levels may better represent the number of particles that cause atherosclerosis (fatty buildup in the arteries).
Lowering Your Risk
Although it's important to know your cholesterol levels, lifestyle changes and other strategies are crucial for reducing heart disease risk. They include…
- A Mediterranean-style diet, which emphasizes fruits, vegetables, fish, whole grains and the use of olive oil as the main vegetable fat—and includes only small amounts of meat and saturated fats-is associated with very low cardiovascular disease risk.
- Regular exercise can increase HDL by up to 10%—and the weight loss that accompanies exercise can produce an additional 20% to 30% increase.
- Omega-3 fatty acids, taken either by prescription or as high-dose fish oil, can lower triglycerides a type of blood fat) by about 40%. This treatment often is combined with other lipid-lowering drugs under the care of a physician.
- Statin drugs, such as simvastatin (Zocor), lovastatin (Mevacor) and atorvastatin (Lipitor), which work primarily by lowering LDL cholesterol as well as inflammation, are among the most effective ways to lower cardiovascular risk. In general, every 1% reduction in LDL reduces the risk for heart attack by 1%.
- Niacin. Nicotinic acid, a form of niacin, has long been known to raise HDL by up to 30%.
But the real benefit of niacin now is thought to be due to improvements in reverse transport and its additional ability to lower levels of triglycerides and LDL. Niacin also makes LDL particles less toxic to the arteries by favorably changing the chemical properties of LDL and HDL-and is used to lower Lp(a) levels.
Caution: Because improper use of niacin can cause serious liver damage, it should be taken only in prescription form under a doctor's supervision