What Is Cholesterol?
About 20 percent of blood cholesterol comes from the food you eat; the rest is produced by your body, primarily by the liver and the intestines. Cholesterol is essential to the function of every cell in the body for structural support of the membranes.
It is also a component of the brain and of nerve cells, and in the production of hormones such as estrogen, progesterone, testosterone, cortisol and aldosterone. Then, why do we constantly hear that cholesterol is dangerous?
What are lipoproteins?
Cholesterol is a fat substance; this means it is not water soluble and cannot travel in watery blood. Therefore it requires a carrier to be transported along the bloodstream and here is where lipoproteins come into place.
Lipoproteins are particles that are made of cholesterol, proteins and other substances (lipo=fat). They are small carriers, kind of taxis; their function is to carry cholesterol to different parts of the body where it is needed. The outside part of the lipoprotein is mainly protein and the cholesterol comfortably travels through the blood inside the lipoprotein carrier.
Types of cholesterol
Your body manufactures several kinds of lipoproteins:
- High density lipoproteins (HDL) – It is considered the “good” cholesterol as it is high in protein and low in cholesterol.
- Low density lipoproteins (LDL) – it is considered the “bad” cholesterol as it is low in protein and high in cholesterol.
- Very low density lipoproteins (VLDL) – It contains mainly triglycerides, which are fat molecules.
Functions of lipoproteins
- HDL carries cholesterol away from the arterial wall to the liver for recycling or removal from the body. High blood levels of HDL cholesterol are therefore desirable.
- LDL cholesterol transports cholesterol throughout the body for hormone production and cell membrane repairs, but in large quantities it often leaves cholesterol deposits on the walls of blood vessels increasing the risk of heart disease, heart attacks, peripheral vascular disease and stroke.
- VLDL are mainly triglycerides. High levels of triglycerides also increase the risk of heart disease.
The production of triglycerides affects cholesterol
Triglyceride is simple the name scientists give to the fat in the body. The production of triglycerides comes from two main sources: the liver and the foods you eat. In order to make triglycerides, the body grabs parts from other fat molecules, mainly from cholesterol molecules.
Unfortunately, it is the beneficial HDL molecules that take the biggest hit when the liver digs for parts in order to make triglycerides and as a result, the HDL level in the blood drops.
Parts of LDL mo0lecules are also used in the making of triglycerides. The effect, however, is not fewer LDL molecules, but simply smaller ones. These small LDL molecules are too small to be picked out of the blood by the liver, so they don’t get cleared out of the body. Instead they continue to circulate in the blood, which allow them plenty of time to find a nice cozy weak spot in the artery walls where they can attach themselves.
What you end up with, then, are high triglyceride levels, low levels of the beneficial HDL cholesterol, and a lot of small, artery-clogging LDL cholesterol molecules in the blood, all of which spells trouble for the arteries.
For additional information on what causes high levels of triglycerides you can read my article “Have You Checked Your Triglycerides Levels Lately?”.
Risk factors of high cholesterol
High cholesterol is a risk factor for coronary heart disease. Individual cholesterol levels are determined by a combination of genetics and the amount of saturated fat and cholesterol in the diet, as well as lifestyle factors, such as amount of exercise and alcohol consumption.
Preventive and risk-reducing measures include avoiding or limiting consumption of highly saturated fats since the hinder the removal of cholesterol from the blood.
Risk factors include:
- Cigarette smoking
- High blood pressure
- Low HDL cholesterol (less than 35 mg/dl)
- Sedentary lifestyle
- A family history of heart disease.
On the other hand, high HDL cholesterol (60 mg/dl) is a protective factor.
Emilia Klapp, R.D., B.S.