3. LDL, HDL, and Fructose

We have been trained by our physicians to worry about elevated serum levels of low density lipoprotein (LDL), with respect to heart disease. LDL is not a type of cholesterol, but rather can be viewed as a container that transports fats, cholesterol, vitamin D, and fat-soluble anti-oxidants to all the tissues of the body. Because they are not water-soluble, these nutrients must be packaged up and transported inside LDL particles in the blood stream. If you interfere with the production of LDL, you will reduce the bioavailability of all these nutrients to your body's cells.

The outer shell of an LDL particle is made up mainly of lipoproteins and cholesterol. The lipoproteins contain proteins on the outside of the shell and lipids (fats) in the interior layer. If the outer shell is deficient in cholesterol, the fats in the lipoproteins become more vulnerable to attack by oxygen, ever-present in the blood stream. LDL particles also contain a special protein called "apoB" which enables LDL to deliver its goods to cells in need. ApoB is vulnerable to attack by glucose and other blood sugars, especially fructose. Diabetes results in an increased concentration of sugar in the blood, which further compromises the LDL particles, by gumming up apoB. Oxidized and glycated LDL particles become less efficient in delivering their contents to the cells. Thus, they stick around longer in the bloodstream, and the measured serum LDL level goes up.

Worse than that, once LDL particles have finally delivered their contents, they become "small dense LDL particles," remnants that would ordinarily be returned to the liver to be broken down and recycled. But the attached sugars interfere with this process as well, so the task of breaking them down is assumed instead by macrophages in the artery wall and elsewhere in the body, through a unique scavenger operation. The macrophages are especially skilled to extract cholesterol from damaged LDL particles and insert it into HDL particles. Small dense LDL particles become trapped in the artery wall so that the macrophages can salvage and recycle their contents, and this is the basic source of atherosclerosis. HDL particles are the so-called "good cholesterol," and the amount of cholesterol in HDL particles is the lipid metric with the strongest correlation with heart disease, where less cholesterol is associated with increased risk. So the macrophages in the plaque are actually performing a very useful role in increasing the amount of HDL cholesterol and reducing the amount of small dense LDL.

The LDL particles are produced by the liver, which synthesizes cholesterol to insert into their shells, as well as into their contents. The liver is also responsible for breaking down fructose and converting it into fat (Collison et al., 2009). Fructose is ten times more active than glucose at glycating proteins, and is therefore very dangerous in the blood serum (Seneff1 et al., 2011). When you eat a lot of fructose (such as the high fructose corn syrup present in lots of processed foods and carbonated beverages), the liver is burdened with getting the fructose out of the blood and converting it to fat, and it therefore can not keep up with cholesterol supply. As I said before, the fats can not be safely transported if there is not enough cholesterol. The liver has to ship out all that fat produced from the fructose, so it produces low quality LDL particles, containing insufficient protective cholesterol. So you end up with a really bad situation where the LDL particles are especially vulnerable to attack, and attacking sugars are readily available to do their damage.