What causes high cholesterol?

Cholesterol - What is it?

Cholesterol is a waxy substance that's manufactured in your liver and small intestine and found virtually everywhere in your body. Its chemical structure is similar to that of steriods, and is seen as a building block of testosterone and also serves as a chemical ancestor of other hormones that, for better or worse, have major effects on your muscles such as progesterone, oestrogen and cortisol.

Cholesterol is carried around the bloodstream by molecules called lipoproteins. There are 2 types, low-density lipoproteins (LDL), which carry cholesterol to various tissues, and high-density lipoproteins (HDL), which carry cholesterol back to the liver so it can be removed from the body.

What causes high cholesterol?

There are several factors that may contribute to high blood cholesterol:

a diet that's high in saturated fat and, less so, high in cholesterol.
lack of exercise may increase LDL ("bad") cholesterol and decrease HDL ("good") cholesterol.
family history - people are at a higher risk of high cholesterol if they have a direct male relative aged under 55 or female relative aged under 65 affected by coronary heart disease.
being overweight, which may increase LDL ("bad") cholesterol and decrease HDL ("good") cholesterol.
age and sex - cholesterol generally rises slightly with increasing age, and men are more likely to be affected than women.
drinking alcohol excessively.

Rarely, high cholesterol can be caused by a condition that runs in the family called a lipid disorder (familial hypercholesterolemia).
Other health conditions such as poorly controlled diabetes, certain kidney and liver diseases and an under active thyroid gland may also cause cholesterol levels to rise. Some medicines such as beta-blockers, steroids or thiazides (a type of diuretic) may also affect blood lipid levels.

Low-Density Lipoproteins.

LDL is found in larger quantities in the bloodstream. It causes problems becuase as it travels around the body to your organs, its lower density allows some the cholesterol to stick to the blood vessel walls, and eventually blocking them. As the vessels become increasingly blocked the bloodflow to your hearts stops, and eventually the heart itself stops. Experts on all sides of the nutrition debate seem to agree that this is not a good thing. LDL is sometimes referred to as "bad cholesterol".

High-Density Lipoproteins.

HDL works in the exact opposite to LDL. Becuase of its high density, HDL transports cholesterol without letting any of stick to artery walls along the way. HDL saves your heart by pulling excess cholesterol out of places where it can work its mischief and returns it to the liver. HDL is sometimes referred to as "good cholesterol". Women tend to have a higher HDL cholesterol level than men.

Triglycerides.

One other type of blood fat that is worth mentioning. This is the storage form of fat and elevated levels in the blood are associated with increased risk of heart disease and clogging of the arteries.