Cholesterol and Heart Health Part II

Where does cholesterol come from?

Ok, we have learned that how important cholesterol is to our lives. Our next question is where does cholesterol come from? It comes from two sources. The majority of cholesterol is produced by liver, about 1000mg per day. Cholesterol can also come from food sources such as meats, poultry, fish, eggs, whole milk, and cheese. Based on American Dietary Guideline, dietary cholesterol consumption should be limited to fewer than 300mg per day. 

How does cholesterol affect heart health?

To answer this question, we need to look into the transportation of cholesterol. Cholesterols are transferred through blood and carried by lipoproteins, which are shaped like small packages. The inside of the small package is made of fats, and the outside of the small package is made of proteins. There are many lipoproteins which are involved with transporting cholesterols. The two most often heard and most used as health indicators are LDL (low density lipoprotein) and HDL (high density lipoprotein).

LDL acts as a glue to fix damage in your circulatory system. If there is damage in your arteries, LDL would be deposited in the damaged area to fix the damage.  On the flip side, if there is no damage in your arteries, LDL would not be deposited at all. Therefore, the real problem is arterial damage, which is the real start of cardiovascular disease. Arterial damage is caused by high blood pressure, smoking, poor dietary choices, and some other factors.

HDL acts as a scraper to remove excess LDL cholesterol and transport it from the arteries to the liver. Then, the liver removes cholesterol by converting it to bile salt and putting it into the bile where it can be eliminated in the feces.

The Problem with LDL Cholesterol:

There is a problem with excessive LDL deposition. If there is too much damage in your arteries, then there will be too much LDL expressed to repair damage. Like we talked about earlier, LDL acts as a glue or band-aid. LDL binds to the damage sites, preventing hemorrhage and blood loss. Recall that LDL carries cholesterol, which is a fatty like substance. What happens if you sit a bottle of oil open, exposed to air for long time? It will turn rancid. The same as LDL cholesterol, LDL cholesterol starts oxidizing and turns rancid once it is deposited into the damaged arteries.

Damaged arteries and rancid fatty material create inflammation, which sends signals to the immune system to help the repair. Platelets are sent to stop the inflammation. Remember, LDL cholesterol is deposited into the blood vessel, and forms a small plaque.  Platelets mix into the sticky LDL cholesterol plaque to form a larger bandage. Eventually, the bandage becomes too big, which narrows the arteries. Then, something like a blood clot or loose cholesterol plaque blocks the remaining space, which leads to lack of blood flow and cell-death.

If the arterial damage is in your heart, it may lead to heart disease: