What do carbohydrates have to do with cholesterol?
Most people believe that carbohydrates and cholesterol are completely unrelated. After all, don't fats like saturated fat increase cholesterol levels? What do carbohydrates have to do with it?
There's actually a powerful relationship between carbohydrates and cholesterol. First of all, cholesterol is nothing more than the substance measured to indirectly quantify the number of various particles in the blood. "High cholesterol" simply means that there are a larger number of blood particles that contain cholesterol. Cholesterol is used to estimate the number of low-density lipoproteins (LDL) and high-density lipoproteins (HDL).
Carbohydrates enter into this equation because:
- Carbohydrates increase triglycerides which, in turn, allow more very low-density lipoprotein particles (VLDL) to be produced by the liver.
- Triglyceride-rich VLDL interact with LDL particles, making them smaller. The more VLDL, the more small LDL particles. This will be reflected (though incompletely) in higher LDL cholesterol values.
- Smaller LDL particles are more prone to oxidation--Oxidized LDL particles are more readily taken up by inflammatory white blood cells residing in the artery wall and atherosclerotic plaque.
- Smaller LDL particles are more prone to glycation--Glycation of LDL is an important phenomenon that makes the LDL particle more atherosclerotic plaque-causing. Glycated LDLs are not recognized by the LDL receptor, causing them to persist in the bloodstream longer than non-glcyated LDL. Glycated LDL is therefore taken up by inflammatory white blood cells in plaque.
To make matters worse, carbohydrates also make you fat, further fueling the fire of this sequence. (Gain weight, triglycerides go up; lose weight, triglycerides go down. The entire sequence follows.)
In order to break this chain, you must reduce carbohydrates.
Reduce carbohydrates and VLDL and triglycerides drop, often dramatically. VLDL becomes less available to transform large LDL into small LDL. Small LDL particles are no longer available to become oxidized and glycated. Blood sugar is reduced and less likely to provoke LDL glycation.
Yet the USDA, American Heart Association, and the Surgeon General's office all advise you to eat more carbohydrates. The American Diabetes Association tells you to eat 70 grams or so carbohydrates per meal. (Diabetes is the condition that is MOST susceptible to these carbohydrate effects.) Follow their advice and you gain weight; triglycerides and VLDL go up; calculated LDL may go up somewhat, but true measured LDL goes way up. Small LDL is triggered, the variety of LDL particle more prone to oxidation and glycation.
What starts this chain? Carbohydrates.
So carbohydrates and cholesterol are indeed intimately related, though it requires a somewhat complex chain of events to see the connection.