You’ve heard of “bad cholesterol.” It’s not what you think. Cholesterol is a form of fat your body uses for many purposes. You’re mostly water. Fat doesn’t dissolve in water, i.e., your blood. So fats are packaged in “lipoproteins,” little round balloons of protein with fats inside. Those fats are triglyceride and cholesterol molecules. Low density lipoproteins (LDL) are the balloons coming from your liver to the tissues carrying the fats you eat or make from sugar. High density lipoproteins (HDL) carry “non-estified cholesterol” (don’t ask me…) from the tissues back to the liver for processing.
In the early years of studying HDL and LDL, researchers thought they found a correlation between higher levels of LDL, arterial plaques where LDL gets plastered and stuck on artery walls, and heart attacks caused by arterial blockage due to the plaques. They noticed that LDL seemed to increase if you ate more fat. They particularly focussed on saturated fats from animals. So eating fat must cause heart attacks, right?
Wrong, according to modern research. Recently an analysis of the supposed evidence used to make the 1977 and 1983 low fat diet guidelines found the evidence wasn’t proper randomized controlled trials (Harcombe et al, 2015). In “The Big Fat Surprise”, Nina Teicholz cites the work of Dr. Robert Krauss, which Lustig, Volek, and Phinney also discuss in their respective writings. It turns out LDL is produced in a range of particle sizes, depending on what you eat. If you eat a lot of fat, your liver makes more “large buoyant LDL.” Your total LDL may be high, but large buoyant LDL doesn’t form plaques. If you eat a lot of sugar or easily digested carbohydrates (breads, pastries, etc.), the particle size distribution shifts toward “small dense LDL.” Those nasty little things often lodge on artery walls and make plaques. That can lead to a blocked artery and a heart attack. This correlates nicely with Johnson’s claim that when societies started eating sugar, their medical literature started reporting heart disease.
Measuring the LDL particle size distribution is a relatively new idea. The Vertical auto profile (VAP) method is more complicated than traditional methods. My GP told me his medical group wouldn’t perform the test. I’m relatively confident I’m at low risk for heart disease, but I’m still curious.