LDL cholesterol tends to be looked at as “the problem” regarding vascular disease risk.  In reality, it is only part of the risk.  What is more important than simply LDL levels is the size of the particles.  Two persons with the “same” LDL level can have very different vascular disease risks.

The LDL listed on a blood lipid panel is expressed in mg/dL which is milligrams per deciliter.  This is basically the total weight (mgs) of cholesterol in a certain size cup (dL).  What makes up the weight of cholesterol in two different similar cups can be very different.

Cholesterol made in the liver cannot be directly put into circulation as that would be trying to mix fat into a water medium.  This is much like trying to mix olive oil into a glass of water.  Try as one might it will not mix.  The solution with cholesterol is to connect it to protein which will keep it water soluble.  These proteins are called apoproteins and humans make two general types, apo B and apo A.  Apo B is smaller and makes small dense LDL particles.  Apo A is larger and makes large, less dense particles.

This example shows the LDL level from two different persons.  Both have an LDL of 130 mg/dL yet they look very different.  One has many small apo B particles and fewer apo A large particles making up their 130 mgs.  The other has fewer but bigger apo A particles making up their 130 mgs.

The small particles are highly associated with vascular disease risk while the larger, apo A particles are not.  Same test “result” but different vascular disease risk.  How much apo B and apo A each of us make is partly set by genetics (not modifiable) and partly set by diet (highly modifiable).

The first question naturally for each is “which am I, apo B or apo A.”  There are two ways to determine this.  One is to have a second blood test called an NMR LipoProtein Profile.  The other is to look at other factors on the original cholesterol panel.  This will include another marker, VLDL cholesterol.  This is LDL “sibling” and a potent predictor of apo B, small particle size.  The lab range generally will call VLDL levels under 40 mg/dL normal.  The healthy range, however, is under 20.  VLDL cholesterol is all made on apo B.

While the liver always makes some VLDL, its production is greatly increased when triglycerides production is high.  When humans consume a diet high in quickly digestible carbohydrates and especially those with added sugar, blood glucose elevates quickly exceeding cell energy need for the moment.  This excess glucose is routed to the liver to be converted to triglyceride for storage in belly fat. 

Higher amounts of VLDL is made to help carry some of that triglyceride to storge. When the VLDL drops off the triglyceride, it becomes small dense LDL which is highly associated with vascular disease.  This dynamic is a major factor in why diabetics have high vascular disease rates.

The graphic shows VLDL with high amounts of triglyceride and cholesterol.  The progression from left to right shows the stripping of triglyceride from VLDL to form small dense LDL.

While a VLDL level greater than 20 mg/dL is a good indicator of small, risky LDL, triglyceride above 150 mg/dL is another good indicator.  VLDL and triglyceride levels will almost always elevate together indicating a genetic patterning that is being worsened by diet.  That diet imbalance is too much quickly digestible carbohydrates and added sugar.  Those carbohydrates include refined grain and starches such as potatoes and rice.

A measure of how quickly digestible a carbohydrate is and how much and for how long it will raise blood glucose is glycemic load.  For a reference, the glycemic loads of cookies, candy bars and sweetened drinks (often referenced as junk food) generally are between 15-40.  A vegetable in contrast typically have a glycemic load of 1-3.  Whole fruits are typically between 3-10.  Surprisingly the glycemic loads of grain products and starches run between 15-45; no different than the junk foods.

I often tell patients that I would rather have an LDL level of 140 if VLDL is <20 and triglycerides <125 than an LDL of 120 with high VLDL and triglyceride.  An LDL of 140 with a large particle size is less risky that an LDL level of 120 that is small particle.

The moral of all of this is always look at LDL’s siblings, VLDL and triglyceride to know the whole story.  If the siblings are off, the problem is too much high glycemic load carbohydrate and sugar in a genetically susceptible person.  As genetics are unmodifiable, fix what can be modified – diet.