I was reading the reviews of Gary Taubes' new book Good Calories, Bad Calories on the Amazon.com website and was amused to see that for the most part the reviewers gave him either 1 Star or 5 Stars.  He was either loved or hated.  There must be many good reasons for such a polarized reception to what he had to say but my impression was that the line in the sand was drawn based on his discussion of the "fat vs carbohydrate" hypothesis.

Much of the literature studying the impact of various subcategories of macronutrients (such as saturated fat, trans fat, starch, and rapidly absorbed or refined carbohydrates) on vascular disease has been limited by the tools available for evaluating their propensity to modulate specific lipid parameters or other biological endpoints.  Variances in these variables are then related to heart attack rates, strokes, Alzheimer's disease or other cardiovascular endpoints.  As technology advances, the tools become available to more intimately dissect and measure physiologic indicators that will ultimately be found to reliably predict desired clinical outcomes of interest.  Until appropriate tools are available, scientists must often rely on inadequate metabolic measurements and opine about their prognostic implications.

In his review of the science behind the 'fat' hypothesis of heart disease, Mr. Taubes starts with the parameter of choice at the time, that being TC (Total Cholesterol).  He describes how it was quantitated in thousands of persons in numerous large studies designed to prove that TC was a predictor of future heart disease in broad population groups (as opposed to those subjects with familial hyperlipidemia).  Since the distribution of TC was almost superimposable between the groups with and without heart disease, it clearly was a poor discriminator between the two.

Following TC as the preferred indicator was LDL cholesterol (a. k. a.-the 'bad' cholesterol).  This was a bit better.  The latest, and hopefully most discriminating parameter thus far is the subclass determination of LDL cholesterol as measured by gradient gel electrophoresis.  This is a blood test that identifies the component particles that are the purported 'bad actors' in the heart disease saga-the small, dense LDL particles located in subfraction IVb.  Levels above 10% appear to identify those individuals who are at greatest risk of undergoing invasive cardiac surgeries such as angioplasty, stenting, and bypass procedures. 

This parameter is directly related to serum triglyceride levels and inversely related to HDL cholesterol (the 'good' cholesterol) levels.  The small, dense LDL particles are those that studies have shown are the most likely to damage blood vessels.  Because they vary as the HDL and TG levels do, they are intimately related to the action of insulin and insulin and blood sugar levels.  They are also linked to inflammatory mediators such as CRP (C-reactive protein), an indicator of inflammation throughout the body and a well-established predictor of future cardiac events.

Hopefully as measurement of LDL subclasses become more commonplace, discourses on heart disease will become less divisive.