Unforgiving small LDL particles
Small LDL particles are triggered by carbohydrates in the diet: Eat carbohydrates, small LDL particles go up. Cut carbohydrates, small LDL particles go down.
A typical scenario would be someone starts with, say, 2000 nmol/L small LDL (by NMR) because they’ve been drinking the national Kool Aid of eating more “healthy whole grains” and consuming somewhere around 200 grams carbohydrates per day, including the destructive amylopectin A of wheat. This person slashes wheat followed by limiting other carbohydrates and takes in, say, 40-50 grams per day. Small LDL: 200 nmol/L.
In other words, reducing carbohydrate exposure slashes the expression of small LDL particles, since carbohydrate deprivation disables the liver process of de novo lipogenesis that forms triglycerides. Abnormal or exaggerated postprandial (after-eating) lipoproteins that are packed with triglycerides are also reduced. Because triglycerides provide the first lipoprotein “domino” that cascades into the formation of small LDL particles, carbohydrate reduction results in marked reduction in small LDL particle formation.
So let’s say you are doing great and you’ve slashed carbohydrates. Small LDL particles are now down to zero–no small LDL whatsoever. What LDL particles you have are the more benign large variety, say, 1200 nmol/L (LDL particle number), all large, none small. You are due for some more blood work on Thursday. On Tuesday, however, you have four crackers because, what the heck, you’ve been doing great, you’ve lost 43 pounds, and have been enjoying dramatic correction of your lipoprotein abnormalities.
Your next lipoprotein panel: LDL particle number 1800 nmol/L, small LDL 700 nmo/L–substantially worse, with a major uptick in small LDL.
That’s how sensitive small LDL particles can be to carbohydrate intake. And the small LDL particles can last for up to several days, since small LDL particles are not just smaller in size, they also differ in conformation, making them unrecognizable by the normal liver receptor. The small LDL particles triggered by the 4 crackers therefore linger, outlasting the normal-conformation large LDL particles that are readily cleared by the liver.
This phenomenon is responsible for great confusion when following lipoprotein panels, since a 98% perfect diet can yield dismaying results just from a minor indulgence. But, buried in this simple observation is the notion that small LDL particles are also extremely unforgiving, being triggered by the smallest carbohydrate indulgence, lasting longer and wreaking their atherosclerotic plaque havoc.