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Understanding HDL: Superhero of Your Arteries

Low-density lipoprotein cholesterol (LDL) is a major contributor to CAD, but not the only cause. Risk of getting CAD can be reduced by approximately 20 to 40 percent if you can get your LDL down to optimal range. This sounds good until your realize that we still have 60 to 80 percent available for further risk reduction. This is where the benefits of raising HDL come in. Cardiac risk is thought to drop by 2 to 3 percent for each 1 mg/dL increase in HDL.

            High-density lipoprotein (HDL) is the “good” cholesterol. It’s considered good because it facilitates reverse cholesterol transport (RCT). Low HDL cholesterol is an important risk factor for CAD. Anyone with atherosclerosis should be interested in RCT, which means taking cholesterol away from where you don’t want it and metabolizing it. HDL helps remove cholesterol from arteries in the early stages of disease and from established atherosclerotic plaque. This is why having low HDL is a risk factor and also why raising HDL to as high a level as possible helps reverse plaque! The importance of raising HDL cannot be overstated, but it is often understated in conventional medicine. Data shows that raising HDL gets similar or even better results than lowering LDL.

            Just in case I have not convinced you about how important it is to raise HDL, you may find the data below more convincing:

  1. The prevalence of CAD increases by 25 to 30 percent for every 10 mg/dL decrease in HDL (below 45 mg/dL) (Castelli et al. 1986).
  2. Statistics show that people with HDL less than 45 mg/dL have two to seven times more occurrences of CAD compared to people with HDL greater than or equal to 65 mg/dL (Castelli et al. 1986).
  3. The risk of cardiovascular events increases markedly with decreasing HDL concentration at every level of LDL concentration (Kannel 1987). This means that even in people whose LDL is less than 100 mg/dL, the risk of developing atherosclerosis increases as HDL declines (Kannel 1987).
  4. People with LDL below 70 mg/dL but whose HDL is in the highest twenty-fifth percentile have a reduced risk of major cardiovascular events compared with people in the lowest twenty-fifth percentile. HDL promotes arterial repair and prevents and corrects endothelial dysfunction (Norata and Catapano 2005).
  5. HDL has been shown to help arteries relax and to inhibit white blood cells from entering plaques (Norata and Catapano 2005; Shah et al. 2001). HDL’s antioxidant properties inhibit the oxidation of LDL. Oxidized cholesterol is associated with increased damage to the endothelium and continues to be investigated as a risk factor in CAD (Libby 2002; Norata and Catapano 2005).
  6. Raising your HDL to above 60 mg/dL may also reduce factors that increase the risk of forming a blood clot and help the body break down blood clots (Griffin et al. 1999).

Increased reductions in plaque formation may occur the lower your LDL goes (to a level of 40 mg/dL). Going lower than 40 mg/dL does not provide any additional benefit.  By raising your HDL to greater than 60 mg/dl, even greater protection and reductions in plaque may be seen. How much plaque regression you can achieve will depend on your lipoprotein pattern and other risk factors. I always try to achieve an HDL that is greater than LDL in all my preventive cardiology patients. As a rule of thumb I tell people 60/60/60. This is easy to remember and means that your LDL should be 60, your HDL should be at least 60, and your triglycerides should be around 60.
[Figure 3-4. Figure 8: The lifecycle of an HDL particle. The picture below is meant to show that an HDL particle is made in the liver and then grows in size as it collects cholesterol. Having larger HDL particles may indicate good reverse cholesterol transport.] [k1] 
            The prevalence of CAD increases by 25 to 30 percent for every 10 mg/dL decrease in HDL (below 45 mg/dL), and people with HDL of less than 45 mg/dL can have up to seven times the increased risk of a heart attack compared to people with higher HDL (Castelli et al. 1986). Even if your LDL is less than 100 mg/dL, as HDL-C declines, the risk of developing atherosclerosis continuously increases, and as LDL increases you have a higher risk of getting CAD with low HDL than if it is higher (Kannel 1987). This is why I look at the total cholesterol-to-HDL ratio and the LDL/HDL ratio.

            Even among individuals with LDL below 70 mg/dL, people with higher HDL have a reduced risk of major cardiovascular events compared to those with the lowest levels (Norata and Catapano 2005). This is because HDL promotes endothelial health and prevents and corrects endothelial dysfunction.

            HDL helps arteries relax[1] as well as inhibits white blood cells from entering plaques (Shah et al. 2001). These are all vasoprotective effects. The antioxidant properties of HDL inhibit the oxidation of LDL to oxidized LDL (ox-LDL); ox-LDL is associated with increased damage to the endothelium and continues to be investigated as a player in heart disease (Norata and Catapano 2005). Raising your HDL to over 60 may also reduce coagulation (clot formation) and platelet adhesion (clot formation risk factor) and help promote the body’s ability to break down clots (Griffin et al. 1999).


[1] Knowing your HDL is optimal should make you relax too because your risk is significantly reduced.

 [k1]Layout: Please note callout for Figure 3-4. Also note “below.” Please adjust depending on the orientation of the figure.