Cholesterol is a waxy material found throughout the body.

            The body needs cholesterol to digest dietary fats, make hormones, build cell walls and other important processes. Too much cholesterol in your body means you have a higher risk of developing heart disease. Over time, if you have too much cholesterol in your body, it can build up on the walls of the arteries that carry blood to your heart. This leads to accumulation of cholesterol laden "plaque" in the vessel linings, a condition called atherosclerosis, which impedes blood flow. When this happens the heart muscle becomes starved for oxygen, causing chest pain (angina). If a blood clot completely obstructs a coronary artery affected by athersclerosis, a heart attack (myocardial infarction) or death can occur.

   

Accumulation of cholesterol laden "plaque" in vessel linings is called "atherosclerosis"

   

Right: artery with "plaque"
Left: artery without "plaque"


People get cholesterol in two ways:

1.

The body, mainly the liver, produces varying amounts daily.

2.

It comes directly from foods from animals (Vegetables contain no cholesterol).


            Typically the body makes all the cholesterol it requires, so people don't need to consume it. Saturated fatty acids are the chief culprit in raising blood cholesterol. Some excess cholesterol is removed from the body by the liver. The Canadian Heart and Stoke Foundation recommends that you limit your daily average cholesterol intake to less than 300 mg (and 200 mg if you have heart disease).


Several Factors affect blood cholesterol:

1.

Heredity   Often high cholesterol runs in families. Genes play an important role in influencing blood cholesterol

2.

Weight   Excess weight tends to increase blood cholesterol.

3.

Exercise   Regular physical activity may not only lower LDL-C (bad cholesterol) but it increases the HDL-C (good cholesterol).

4.

Age and Gender   Before menopause, women tend to have total cholesterol levels lower than men at the same age. Cholesterol levels naturally rise as men and women age. Menopause is often associated with an increase in LDL-C and a decrease in HDL-C.

5.

Stress   Experts say people sometimes over eat fatty foods when under stress. This practice or behaviour can contribute to high blood cholesterol.


Cholesterol Breakdown


High ("Healthy") Density Lipoprotein (HDL-C)

This is the "GOOD" cholesterol. . It prevents cholesterol from building up in the arteries. It is mostly protein and contains only a small amount of fat. HDL-C clears the bad cholesterol from the body by picking up cholesterol from the walls of the arteries and carrying it back to the liver for disposal. Exercise increases the production of HDL-C. A higher HDL-C is linked with a lower risk of heart disease, stroke and atherosclerosis. Exercise can also help control weight, diabetes and high blood pressure. Exercise that uses oxygen to provide energy to large muscles (aerobic excercise) raises your heart and breathing rates. Stopping smoking will also improve HDL-C levels.

Estrogen (female sex hormone) and moderate alcohol intake can also raise HDL-C. One reason why women are relatively protected from heart disease prior to menopause appears to be related to the fact that women have higher levels of HDL-C as compared to men. Women are just as likely as men to die for heart disease but the onset tends to be later in life.


Low ("Lousy") Density Lipoprotein (LDL-C)

This "BAD" cholesterol is carried into the blood and is the main cause of harmful fatty buildup in the arteries. LDL-C is mostly fat with a small amount of protein. The higher the LDL-C level in the blood, the greater the risk of heart disease. LDL-C is strongly influenced by genetic factors. One of the other important causes of elevated LDL-C levels is a diet high in saturated fats (fats found in animal products), trans fatty acids (hydrogenated fats) and cholesterol (found only in animal products).


Lipoprotein (a) Lp(a)

Lp(a) is a genetic variation of plasma LDL-C . LDL transports most of the cholesterol in the blood. When high levels of cholesterol are present in the blood, Lp(a) promotes the buildup of plaque (cholesterol deposits) in the arteries and interferes with the break down of blood clots. All of this leads to the increase risk of stroke and heart disease. The risk associated with high LP(a) levels can be decreased by lowering LDL- levels through diet (low in saturated fats and cholesterol) or medication (statins), treatment with niacin and by maintaining normal body weight and following an exercise program.


Desirable Lipid Levels

 

No Risk Factors

Risk Factors

CHD/DM*

Cholesterol
(mmol/L)

Below

5.2

5.0

4.5

Triglycerides
(mmol/L)

Below

2.0

2.0

1.7

LDL-C
(mmol/L)

Below

3.5

3.0

2.5

HDL-C
(mmol/L)

Above

1.1 (Men)
1.2 (Women)

1.1 (Men)
1.2 (Women)

1.2 (Men)
1.3 (Women)

Lp(a)
(mg/dl)

Below

25

25

25


*CHD/DM: Desirable lipid levels for persons with: Coronary heart disease, stroke, TIA, peripheral vascular disease or diabetes.
Major risk factors for CHD include smoking, diabetes, high blood pressure, family history, sedentary lifestyle, stress, low HDL-C, elevated LDL-C, males over 45, women over 55.