What is cholesterol?

Everybody has heard about "bad cholesterol" and "good cholesterol"... but, what's that?

Cholesterol is a fatty substance found in the blood of humans and also in the outer lining of cells (membrane) in the body of animals. The cholesterol that we have in our blood comes from two different sources:
- liver production
- diet: meat, fish, dairy products...

After each meal, cholesterol is absorbed by the intestines, goes into the blood and then it's packaged inside a protein coat. These proteins are removed then by the liver.

When you go to the doctor, you are suggested to keep the "bad cholesterol" in blood low and the "good cholesterol" high. Ok. What does this mean?

# Bad cholesterol or LDL-low-density lipoprotein: These proteins deposit cholesterol on the artery walls, causing the formation of a hard substance named cholesterol plaque. With the time, this plaque leds to the narrowing of the arteries in a process called atherosclerosis. Because of it, the arteries can get blocked, so LDL is associated with a higher riks of coronary heart diseases.

When the liver has many LDL receptors, this helps to remove more rapidly the LDL cholesterol from the blood, helping to keep the bad cholesterol levels low. The number of LDL receptors depends on both heredity and diet. For instance, people with familiar hypercholesterolemia have a very low number of LDL receptors, so they usually have high levels of bad cholesterol. Besides, the bad cholesterol level can raise with diets high in saturated fats (certain vegetable oils and products derived mainly from meat and dairy products).

# Good cholesterol or HDL-high-density lipoprotein: These particles extract cholesterol from the artery walls and dispose them through the liver. So they prevent atherosclerosis.

Life style factors and other conditions influence HDL cholesterol levels. HDL cholesterol levels are for instance lower in smokers, people who eat a lot of sweets, and also in those who are overweight and inactive. On the other hand, estrogen increases the HDL cholesterol level, so usually women have higher good cholesterol levels than men.

These are some websites with interesting suggestions to keep your cholesterol at healthy levels, though anyway I advise you to visit your doctor if your levels are wrong:
- Low cholesterol diet
- Cholesterol Lowdown