Dietary factors have been known to contribute to cardiovascular health for decades. This area continues to be a major area of research into human health. Components of diet can also affect cholesterol levels, so it is natural to discuss both topics together.
Elevated cholesterol levels have long been established to increase the risk of cardiovascular disease. As prior columns have reported, cardiovascular disease is the number-one cause of line-of-duty deaths among firefighters. This is important since screening for elevated cholesterol levels and controlling cholesterol levels is a primary therapy at preventing cardiovascular disease. Preventing cardiovascular disease reduces the chance of having a heart attack.
While guidelines in the past focused on total cholesterol levels, current guidelines focus on the subtypes of cholesterol that may not be familiar to some. The first component of cholesterol is low-density lipoproteins (LDL). This also is referred to as the "bad cholesterol." LDL cholesterol is responsible for transporting cholesterol that is synthesized in the liver to the peripheral tissues. It is thought that LDL cholesterol deposits cholesterol molecules in the walls of damaged blood vessels, contributing to atherosclerosis, or plaque formation, within the blood vessels. It is these plaques that rupture in the arteries of the heart and cause heart attacks. Elevated LDL levels are a risk factor for cardiovascular disease.
The other component of cholesterol is high-density lipoproteins (HDL). This molecule has the opposite mechanism of LDL cholesterol and is considered the "good cholesterol." HDL cholesterol transports cholesterol molecules from the peripheral tissues back to the liver for processing. Higher levels of HDL cholesterol are considered a negative risk factor for cardiovascular disease and reduce the risk of cardiovascular disease. Table 1 lists the classification of the two different types of cholesterol.
In the past, preventative measures for cardiovascular disease looked at total cholesterol levels for overall cardiovascular disease risk. However, because of the different natures of the two subtypes of cholesterol, risk-reduction measures factor the levels of both types of cholesterol with the main focus on LDL levels instead of total cholesterol levels. High LDL levels increase the risk of cardiovascular disease while high levels of HDL cholesterol reduce the risk. Understanding this concept will help you communicate with your health care provider when discussing cholesterol levels and help you take control of your health.
Determining a goal LDL level also depends on your overall risk of cardiovascular disease (Table 2). In general, an LDL level less than 100 is optimal with a level greater than 130 being considered high. For patients with established cardiovascular disease or diabetes, the goal LDL is less than 100 (Table 3). From a preventative medicine standpoint, diabetics are at such an increased risk of developing cardiovascular disease that these patients are considered having cardiovascular disease even in the absence of an established diagnosis. For patients with two or more risk factors for cardiovascular disease, the goal LDL is less than 130. If you only have one or less cardiovascular risk factor in Table 2, your goal LDL is 160, but still lower levels are optimal. Also, an HDL level greater than 60 is a negative cardiovascular disease risk factor; the total number of cardiac risk factors from Table 2 is reduced by one. For example, using Table 2, if you are over 45 and are being treated for high blood pressure, using Table 3 you have two cardiovascular risk factors and your goal LDL is less than 130. Now if you have an HDL level greater than 60, your total number of risk factors is reduced by one and your goal LDL is less than 160.