What Is A Healthy Cholesterol Level?

One of the realities of cholesterol measurement is that some people who have "low cholesterol," referring to total cholesterol, will develop cardiovascular disease, and some people who have "high cholesterol" will not.

Don't Take LDL Readings at Face Value

That is also true of LDL levels. LDL actually is not measured by lab tests. It is estimated. The lab measured total lipids, triglycerides, and HDL cholesterol. VLDL and LDL cholesterol are not measured.

As a rule of thumb, VLDL cholesterol is estimated as 1/5 of triglycerides, and then the "bad" cholesterol is calculated with a simple mathematical formula:

LDL = Total lipids - HDL - triglycerides - (1/5 of triglycerides)

Since LDL is an estimate, however, measurement can go wrong. If you go on a diet, your body has fewer excess carbohydrates and fatty acids to store as triglycerides. When the lab is simply applying the formula rather than directly measuring LDL cholesterol (a test that typically costs an additional $500 or so in the USA and is not available in other countries because of cost), lowering triglycerides artificially inflates the LDL number.

It is not unusual for people to be told they have "borderline high cholesterol," go on a diet, and then be told they need medication. The test simply does not take into account good behavior. There are similar problems when diabetics get their triglycerides down by lowering their blood sugar levels. 

This means that lab values for LDL tend to be higher than true values. But it isn't "LDL" that causes cardiovascular disease.

When LDL Levels Are Not "Normal"

Many commentators believe that since "LDL" is not really the cause of cardiovascular disease, and the lipoprotein apo-B1 that actually causes heart disease is not usually measured, then it is OK to ignore cholesterol. This turns out not to be a good idea.

While LDL is not the precise cause of heart and blood vessel disease, it turns out that apo-B1 goes up and down in a relatively tight relationship to the measurement of total LDL. If you have high LDL, especially if you have high triglycerides, then steps to manage your cholesterol (such as taking a statin drug) actually are a good idea.

What is a safe and normal cholesterol level, then? Since cholesterol is not the only factor in the development of cardiovascular disease, normal levels of cholesterol vary. Here are some good guidelines:

• If you smoke, if you have diabetes, if you have had heart disease, or if a close family member has had heart disease, an LDL level of 190 mg/dl or more indicates a need for immediate treatment. An LDL level of 160 mg/dl also requires treatment, probably with smaller doses of statin drugs. Getting LDL down to 70 mg/dl or lower is optimal.

• If you do not have any risk factors for heart disease, then you probably won't be treated for high cholesterol as long as your LDL is 160 mg/dl or lower.

However, LDL cholesterol is just one factor in heart disease. Triglycerides are another. Even if you have good LDL and total cholesterol levels, many doctors will put you on statin drugs if your triglycerides are over 150 mg/dl, even if your cholesterol levels are normal.

The cholesterol myth is just a myth. Cholesterol levels really do make a difference in whether you get heart disease. While it is best if your doctor orders measurements of apo-B1, high LDL cholesterol levels also require medication.