February 20, 2017

Cholesterol Part IV - Endothelial Dysfunction

How does an artery clog?

Now we are going to continue to move well beyond just cholesterol. The artery as discussed last week has an endothelial lining made up of layered thin cells that lay on top of a muscle layer which lays on top of connective tissue making the tube complete. This area is where the dysfunction occurs that leads to a heart attack.

The process starts at very young ages. Teenagers have early signs of endothelial dysfunction long before the blood pressure is high or other markers are seen. According to Dr. Houston, "the process is begun because of chemical stressors and epigenetic forces. Oxidative stress, inflammation and autoimmune dysfunction initiate and propagate hypertension and cardiovascular disease".

As we discussed last week, oxidative stress and inflammation begin in the body when we consume poor quality food and are exposed to toxins and infections initiating chemical reactions in the gut and blood stream that lead to damage.

Let us start with sugar and flour because we know that diabetes is one of the greatest risk factors for heart disease. People who consume large volumes of flour and sugar encourage the hormones insulin and leptin to up-regulate the liver enzyme HMG CoA reductase making more LDL cholesterol while simultaneously pushing sugar molecules into fat cells engorging them. When they continue to get enlarged unchecked, they become oxidized, glycated and targeted by the immune system for death. An immune cell called a macrophage within the artery wall swallows small dense oxidized LDL lipoproteins that have slipped into the endothelium becoming a foam cell. This foam cell continues to swallow more LDL becoming engorged and dysfunctional releasing signals that start a local chemical reaction via the immune system that leads to further damage of the artery wall and then the development of a plaque.

Let us now add in certain fats that get incorporated into our cell membranes. The concerning ones are the chemically manufactured trans fats and vegetable based poly unsaturated omega 6 fats (PUFA). These fats are primarily derived from the oils of soybeans, corn and rapeseed/canola. They are found in our fryers and junk foods. These fats are unhealthy primarily because they have unstable chemical structures that at high heat or when exposed to pro oxidants become altered to an oxygen radicalized fat like lipid peroxides or oxidized LDL cholesterol.

These fats damage the cell membrane, mitochondrial energy center and cell signal molecules when they are oxidized. Again, we have a scenario where an abnormal fat cell has been stuffed by sugar and the cell membrane is damaged by PUFA's making it an immune reactive foam cell that is inflaming the area that it has invaded in the artery wall.

What else is contributing to the inflammation here? My personal favorite is the abnormal microbes that inhabit your gut. In previous lectures I showed that the standard American diet, high refined sugar and PUFAs, promote the wrong types of bacteria to grow in the gut. Gram negative rod bacteria is one such class that releases a chemical called a lipopolysaccharide or LPS for short. This bacterial cell wall debris directly stimulates the immune system to fight via toll like receptors. Remember from two weeks ago that the lipoproteins like LDL carry these bad boys to the liver for detoxification. However, when the lipoproteins get oxidized and glycated they are less functional and have reduced innate clearing capacity further increasing inflammation.

The process occurs over years as the immune system continues to fight the good fight in the gut and blood stream as the human offender continues to stuff fat cells with sugar, flour and bad fats. The heart vessel wall develops a plaque of hardened and calcified fat that starts to block the vessel. When this plaque ruptures based on an acute stress, then platelets come to clot the damage and occlude the vessel causing the flow of oxygenated blood to not reach the heart muscle. This causes the heart muscle cells to die, i.e. a heart attack.

If the vessel is a major source of blood to the heart muscle, you can suffer an infarction that prevents the heart from being able to pump and you are unfortunately dead.

I have been asked why a pediatrician is focusing on a heart attack when they never occur in kids. The answer is that most disease of adulthood can be prevented if we teach our kids this truth.

I know that I have simplified this complex topic down to a few major problems. There are genetic outliers on both sides of this spectrum, however, for the vast majority of us, the consumption of refined flour, sugar, trans fats, oxidized PUFA's, exposure to chemicals and toxins are likely the root cause of our coronary artery disease risk.

Next week: what is the recipe for success?

Dr. M

Deep Nutrition, Catherine Shanahan, MD
http://www.slideshare.net/autumnpianist/atherosclerosis-and-myocardial-infarction (see slides 7-9)