Steve Parcell, ND
Lipoproteins are a better measure of risk, and lipoprotein testing represents a new era in preventive cardiology. Just measuring LDL and treating it (while still somewhat effective) may not be enough for ultimate heart attack prevention, because it does not reflect lipoprotein size, density, or particle number.
LDL and HDL are just not enough when it comes to evaluating your risk of a heart attack. This is particularly true if the small, dense LDL particle number is elevated. From here on I will refer to LDL particle number as LDL-P.
Most of the cholesterol in your blood is not just freely floating around. Rather, it is in the form of a little ball called a lipoprotein. Apolipoproteins are the protein component of the lipoprotein. They play an important role in what cholesterol does in your body.
There are six major classes of apolipoproteins, and several subclasses. The apolipoproteins determine what the lipoprotein will do and also determine the difference between HDL and LDL. The big red blob in Figure 3-3 is the apolipoprotein component of the lipoprotein. The apolipoprotein tells the cholesterol particle what to do and where to go, as well as determines if it’s going to be a good guy or a bad guy.
You can see fat (triglyceride) and cholesterol inside the ball above. The outer shell of the lipoprotein is also composed of cholesterol and phospholipids. All our cells are mainly composed of phospholipids. If this was an HDL lipoprotein it would get larger as is accumulated cholesterol.
Small Dense LDL and Increased Particle Number
Small dense LDL is more damaging to arteries as compared to large LDL. There are over 20 years worth of studies on this topic, showing that people with smaller LDL size, compared to people with the same level of LDL who have larger LDL particles, have a three to four times greater risk of CAD. At any level of LDL cholesterol, if you have smaller LDL particles, you will have more of them. This can be seen in Figure 3-4, where the scale holds 130 mg/dL of cholesterol on both sides, but the patient on the right is at higher risk because there are more particles and they are smaller.
Why are small particles bad? Think of the net that divides a tennis court. The net represents the first layer in your artery wall. Large particles are like tennis balls that cannot is a in a pass through the net; small particles are like golf balls that can pass right through. Small particles get into the artery wall and accelerate plaque progression within the artery wall. The more lipoprotein particles a person has, the higher the risk for plaque buildup regardless of how much cholesterol those particles carry! This is why LDL alone is not a good way to measure risk. The same holds true for HDL. Larger, more buoyant HDL particles are more protective. Specifically, something called HDL2 is the most protective. Small HDL may even be a risk factor. So, it’s not good enough to just measure HDL with the old testing methodology.