Health care savvy Americans, confident in their cholesterol knowledge, may be in for a surprise. Knowing their cholesterol numbers-and where they should be-is not enough. To protect their heath, consumers need to recognize key myths surrounding cholesterol.

According to experts, the top five include:

Myth No. 1:

If my total cholesterol and LDL cholesterol are “normal,” I don’t need to worry about heart disease.

Wrong. Patients who get their total and low-density lipoprotein (LDL or “bad”) cholesterol results back as “normal” may actually be at risk because standard cholesterol tests fail to measure many cholesterol abnormalities that can lead to heart disease. In fact, almost half of all patients who have heart attacks have “normal” cholesterol, as measured by the standard cholesterol test.

Myth No. 2:

If I exercise and eat healthy, I don’t need to worry about heart disease.

That’s another fallacy. Many people who are at risk or already suffer from heart disease exercise and eat right. That’s because genetics play a significant role in heart disease. In fact, a recent study of male twins, one lean and athletic and the other heavier and more sedentary, found that the brothers tended to show the same cholesterol response to high-fat and low-fat diets.

Myth No. 3:

Women aren’t as susceptible to heart disease as men.

This myth couldn’t be further from the truth. Cardiovascular disease is the No. 1 cause of death in women. In fact, nearly twice as many American women die of heart disease and stroke as from all forms of cancer combined, including breast cancer. High cholesterol is a major risk factor for heart disease and stroke, and women tend to have higher cholesterol than men starting in their 40s.

Myth No. 4:

The routine cholesterol test gives an accurate measure of my LDL cholesterol.

Wrong again. A little-known fact about the routine cholesterol test is that it estimates LDL cholesterol, rather than directly measuring it. This process can result in a significant underestimation of a patient’s LDL level-and resulting heart disease risk.

Myth No. 5:

If my good cholesterol (HDL) is high, I am protected against heart disease.

This may appear true, but there’s a catch: High-density lipoprotein (HDL) consists of subclasses (HDL2 and HDL3). While people with higher HDL2 are more protected against heart disease, those with more HDL3 may actually be at increased risk-even if they have normal total HDL.